Fuse Box Follies (underhood fuse box information)
10-24-2017, 04:11 AM
#1
Thread Starter
Join Date: 08-24-2017
Location: United States
Posts: 7
Fuse Box Follies (underhood fuse box information)
Hello all!
Per donbrew's request, here are a few things I have learned about the underhood fuse box on the other half's 2008 1LT 2.2 manual. Other years and models should be similar, but they won't be exactly the same. Some of this comes from the transmission swap I helped do on this car, and some of it comes from other maintenance adventures.
tl;dr: There is no tl;dr. However, there is a table of contents:
Part 1:
0. Some basics
1. The "stack" of stuff that is the fuse box
2. How I think it was assembled at the factory
3. How to take the fuse box off of the bracket
Part 2:
4. What I had to do to get the fuse box to work on reassembly (the presumed factory way did NOT work)
5. Some other observations. (Some of the relays can be installed BACKWARDS!)
Zeroth, some basics.
If you are contemplating removing the fuse box, please disconnect the battery negative cable first. Also, make sure the disconnected negative cable can't flop over against the battery terminal again when you're not looking. Tuck it out of the way really well, or tie it off to the side, or stick a plastic bag over the end of the cable - like that. The HHR you don't burn down may be your own!
I can't tell you what all the connectors, terminals, relays, and fuses do on your car, unless you happen to have a 2008 1LT 2.2 manual. They are not all the same across years and trim levels.
I don't have wiring diagrams for anything besides a 2008 1LT 2.2 manual, and I won't go get the ones for other years and trim levels.I recommend getting your hands on the original GM diagrams, or professional-level manuals (like Mitchell), if at all possible - check with your local library. If you try to follow a Haynes or Chilton wiring diagram, you're gonna have a bad time.
"Front" means the front of the car. "Left" means the driver's side.
First, I will describe the whole "stack" of stuff involved with the fuse box.
The first thing that happens is a plastic bracket. It is screwed into the sheet metal of the inner fender in a couple of places. The front of the bracket has a place to mount the engine computer. The top of the bracket has four "wells" for the main harness connectors. There are some lugs on all four exterior sides of the bracket, a short distance down from the top edge, that the clips on the fuse box engage.
The "wells" are just rectangular cavities in the top of the bracket. The back one is about 2" (50 mm) front-to-back by 4" (100 mm) side-to-side. The middle one is also 2" x 4". The front two wells are smaller than the others - two 2" x 2" (50 x 50 mm) wells side by side. Each well has a couple of plastic fingers sticking up that latch on to the big connectors. Each well also has a notch somewhere in the outside wall for the harness to go through.
Four big harnesses are connected to the fuse box. Each one ends in a connector. The connector housings are either grey or black plastic, with red inserts to retain the electrical terminals. Each connector has a captive brass nut right in the middle of the top. On the bottom of each connector, there is a plastic cover clipped on, that covers where the wires break out of the corrugated loom and go to their individual terminals. It's normal for not all of the terminals to be in each connector. Some terminals will always be there; some will only be populated if your car has certain options.
Each connector fits in one of the four wells in the bracket. The plastic fingers in each well keep the connector from moving up and down very much, but they do allow the connector to move around a little front-to-back and side-to-side.
The fuse box itself is made out of a couple of big pieces of plastic, roughly 6" x 4" (150 x 100 mm). The top piece has all the recesses for the fuses and sockets for the relays molded into it... it's what you see when you're checking the fuses. The bottom piece has slots in it with a bunch of flat terminals sticking out of it; these mate with the four connectors described above. The top and bottom pieces of plastic are connected together by lugs and latches around the outside edge. There are more latches sticking down around the outside edges, that engage with lugs on the bracket to hold the fuse box down.
I have seen a photo online of what it looks like when you separate the top and bottom pieces of the fuse box - basically there are a bunch of small stamped metal bars running from the fuse and relay sockets on top, to the terminal pins on the bottom. I don't recommend trying to separate the top and bottom half of the fuse box, unless there are obvious signs of mayhem coming from in there. "Mayhem" includes like sparks, smoke, and melted plastic around a fuse or relay terminal. If you do take one apart (maybe a junk one), it helps to have something wider than a standard flat screwdriver to operate the latches - something like a 1" (25 mm) wide putty knife would be about right. Expect the plastic to be old and brittle; if possible, take it apart on a warm day, or put the fuse box inside the house to warm up for a few hours before taking it apart - like that.
The fuse box also has four captive bolts in it. They stick up above the relays on top, go all the way through both pieces of the box, and stick down below the terminals on the bottom. These bolts engage with the brass captive nuts in the four big connectors underneath the fuse box.
Finally, there is the plastic dust cover that clips over everything. It should have a directory of which fuses and relays do what inside of it.
Second, here is what I think they did at the factory.
I think the bracket went into the car first. Then, the harnesses went in, and they clipped all four connectors into their wells on top of the bracket. They then slapped the fuse box down on top of the bracket, starting all four connectors in one swell foop. (This also probably engages the latches on the fuse box over the lugs on the bracket.) Then, they tightened those four bolts inside the fuse box, to draw all four connectors fully home.
We tried to do this when reassembling the car after swapping the transmission, and ran into problems... more below.
Third, how to take the fuse box off of the bracket by disconnecting the four big connectors.
If you want to get the fuse box entirely out for some reason, disconnect the battery negative cable, take off the red positive cables that have their own stud on the outside edge of the box, and then loosen those four bolts that stick up among the fuses and relays in the box. It may help to loosen each bolt all the way, then screw it back in a couple of turns, then push down on the bolt while you pull up on the fuse box to help disengage the connector from the bottom side of the fuse box - you're using the bolt as a "handle" to push on the otherwise inaccessible connector. Once you feel the connector start to come off of the pins, then loosen each bolt completely. When you lift the box off of the bracket, all four connectors "should" stay in the bracket, freeing the fuse box.
---
More coming in Part 2!
Truckette
Per donbrew's request, here are a few things I have learned about the underhood fuse box on the other half's 2008 1LT 2.2 manual. Other years and models should be similar, but they won't be exactly the same. Some of this comes from the transmission swap I helped do on this car, and some of it comes from other maintenance adventures.
tl;dr: There is no tl;dr. However, there is a table of contents:
Part 1:
0. Some basics
1. The "stack" of stuff that is the fuse box
2. How I think it was assembled at the factory
3. How to take the fuse box off of the bracket
Part 2:
4. What I had to do to get the fuse box to work on reassembly (the presumed factory way did NOT work)
5. Some other observations. (Some of the relays can be installed BACKWARDS!)
Zeroth, some basics.
If you are contemplating removing the fuse box, please disconnect the battery negative cable first. Also, make sure the disconnected negative cable can't flop over against the battery terminal again when you're not looking. Tuck it out of the way really well, or tie it off to the side, or stick a plastic bag over the end of the cable - like that. The HHR you don't burn down may be your own!
I can't tell you what all the connectors, terminals, relays, and fuses do on your car, unless you happen to have a 2008 1LT 2.2 manual. They are not all the same across years and trim levels.
I don't have wiring diagrams for anything besides a 2008 1LT 2.2 manual, and I won't go get the ones for other years and trim levels.I recommend getting your hands on the original GM diagrams, or professional-level manuals (like Mitchell), if at all possible - check with your local library. If you try to follow a Haynes or Chilton wiring diagram, you're gonna have a bad time.
"Front" means the front of the car. "Left" means the driver's side.
First, I will describe the whole "stack" of stuff involved with the fuse box.
The first thing that happens is a plastic bracket. It is screwed into the sheet metal of the inner fender in a couple of places. The front of the bracket has a place to mount the engine computer. The top of the bracket has four "wells" for the main harness connectors. There are some lugs on all four exterior sides of the bracket, a short distance down from the top edge, that the clips on the fuse box engage.
The "wells" are just rectangular cavities in the top of the bracket. The back one is about 2" (50 mm) front-to-back by 4" (100 mm) side-to-side. The middle one is also 2" x 4". The front two wells are smaller than the others - two 2" x 2" (50 x 50 mm) wells side by side. Each well has a couple of plastic fingers sticking up that latch on to the big connectors. Each well also has a notch somewhere in the outside wall for the harness to go through.
Four big harnesses are connected to the fuse box. Each one ends in a connector. The connector housings are either grey or black plastic, with red inserts to retain the electrical terminals. Each connector has a captive brass nut right in the middle of the top. On the bottom of each connector, there is a plastic cover clipped on, that covers where the wires break out of the corrugated loom and go to their individual terminals. It's normal for not all of the terminals to be in each connector. Some terminals will always be there; some will only be populated if your car has certain options.
Each connector fits in one of the four wells in the bracket. The plastic fingers in each well keep the connector from moving up and down very much, but they do allow the connector to move around a little front-to-back and side-to-side.
The fuse box itself is made out of a couple of big pieces of plastic, roughly 6" x 4" (150 x 100 mm). The top piece has all the recesses for the fuses and sockets for the relays molded into it... it's what you see when you're checking the fuses. The bottom piece has slots in it with a bunch of flat terminals sticking out of it; these mate with the four connectors described above. The top and bottom pieces of plastic are connected together by lugs and latches around the outside edge. There are more latches sticking down around the outside edges, that engage with lugs on the bracket to hold the fuse box down.
I have seen a photo online of what it looks like when you separate the top and bottom pieces of the fuse box - basically there are a bunch of small stamped metal bars running from the fuse and relay sockets on top, to the terminal pins on the bottom. I don't recommend trying to separate the top and bottom half of the fuse box, unless there are obvious signs of mayhem coming from in there. "Mayhem" includes like sparks, smoke, and melted plastic around a fuse or relay terminal. If you do take one apart (maybe a junk one), it helps to have something wider than a standard flat screwdriver to operate the latches - something like a 1" (25 mm) wide putty knife would be about right. Expect the plastic to be old and brittle; if possible, take it apart on a warm day, or put the fuse box inside the house to warm up for a few hours before taking it apart - like that.
The fuse box also has four captive bolts in it. They stick up above the relays on top, go all the way through both pieces of the box, and stick down below the terminals on the bottom. These bolts engage with the brass captive nuts in the four big connectors underneath the fuse box.
Finally, there is the plastic dust cover that clips over everything. It should have a directory of which fuses and relays do what inside of it.
Second, here is what I think they did at the factory.
I think the bracket went into the car first. Then, the harnesses went in, and they clipped all four connectors into their wells on top of the bracket. They then slapped the fuse box down on top of the bracket, starting all four connectors in one swell foop. (This also probably engages the latches on the fuse box over the lugs on the bracket.) Then, they tightened those four bolts inside the fuse box, to draw all four connectors fully home.
We tried to do this when reassembling the car after swapping the transmission, and ran into problems... more below.
Third, how to take the fuse box off of the bracket by disconnecting the four big connectors.
If you want to get the fuse box entirely out for some reason, disconnect the battery negative cable, take off the red positive cables that have their own stud on the outside edge of the box, and then loosen those four bolts that stick up among the fuses and relays in the box. It may help to loosen each bolt all the way, then screw it back in a couple of turns, then push down on the bolt while you pull up on the fuse box to help disengage the connector from the bottom side of the fuse box - you're using the bolt as a "handle" to push on the otherwise inaccessible connector. Once you feel the connector start to come off of the pins, then loosen each bolt completely. When you lift the box off of the bracket, all four connectors "should" stay in the bracket, freeing the fuse box.
---
More coming in Part 2!
Truckette
10-24-2017, 04:13 AM
#2
Thread Starter
Join Date: 08-24-2017
Location: United States
Posts: 7
Fuse Box Follies, part 2
Moderator's note: There is a section that is struck through, it is incorrect information.
And here it is.
---
Fourth, what I had to do to get the fuse box to work when putting it back on to the four big connectors.
On the first attempt at reassembling the car,we did it like I think they did it at the factory - all four connectors in the wells, slap the fuse box down, tighten the four bolts, done. When we tried the key, though, some things lit up when the key was in "run", but the starter wouldn't operate when the key was turned to "start". I also noticed that I didn't hear the fuel pump buzz for a few seconds when the key was turned to "run", and some things inside the car, like the heater controls, didn't seem to have power.
I poked around in the fuse box with a test light, and found that all of the hot-all-the-time stuff (circuit 30 in the old country) worked, but some of the hot-with-key-on stuff (circuit 15) wasn't getting power. I was playing with the "RUN/CRNK" relay in the underhood fuse box, which powers some of the hot-with-key-on stuff, and found out that by pushing the relay sideways with my fingers, I could get things to come on, but as soon as I let go, the power would go away again. When I swapped that relay with an identical one, the problem stayed with the socket (it didn't follow the relay), so I didn't think it was the relay.
I figured there might have been a problem with attaching the connectors to the bottom of the fuse box. I went to the back and disconnected the battery, and then went up front, loosened all four bolts, got the connectors loose, and lifted the fuse box off again. I inspected the harness connectors for cracked housings or bent terminals, but they were OK. I inspected the pins sticking down from the bottom of the fuse box for being bent or pushed up into the plastic too far (in other words, not sticking down far enough), but they were OK.
I decided to start a couple of the big connectors by hand. Because the harnesses come out of three sides of the bracket, it would be IMHO very difficult to start all four by hand. I left the back 2"x4" connector and the front left 2"x2" connector in their wells on the bracket. I then held the fuse box above the bracket and gently started the middle 2"x4" connector and front right 2"x2" connector on to the bottom of the fuse box by hand. I think I then started the bolts for those two connectors a couple of turns. Then I held the fuse box as level as I could, and gently pushed it down onto the brackets, to mate the two connectors that were still in their wells. It may help to wiggle the fuse box side-to-side and front-to-back a little as you push down, to help the connectors in the wells get aligned. I tightened all four bolts all the way, hooked the battery back up, and tried it.
Success! Everything inside the car that should have worked, did. I heard the fuel pump buzz when I turned the key on. I twisted the key to start and the starter ran and the engine started. I drove it 3/4 of a mile (1.2 km) to the gas station, and about 1.5 miles (2.4 km) back; everything worked, no trouble codes.
I don't actually know what was wrong or what I did to fix it. My best guess is that when we first slapped the fuse box down, we pushed some of the terminal pins on the bottom of the fuse box up into the box, so they weren't making contact, or only making intermittent contact. When I started the two connectors by hand, and then slapped down the other two, I think I didn't push any of the pins out of the way, so they all connected properly. I think.
Fifth,some other observations about the fuse box.
A) IT IS POSSIBLE TO INSTALL SOME OF THE RELAYS IN THE FUSE BOX BACKWARDS! Some of the relays have 4 pins in a symmetrical pattern. Don't do this, but if you unplug the relay and turn it 180 degrees in yaw, you can sometimes plug it right back in to the socket. The 4 pins are not in the center of the bottom of the relay, so sometimes another fuse or relay will block you from installing the relay the wrong way around. However, some of the relays have enough free space around them that they can be installed backwards. They could have molded a recess for the base of the relay into the fuse box to give you a hint, but they didn't. They could have arranged the relay pinout so it wouldn't matter... but Opel isn't that clever. (Note that the 5-pin relays don't have this problem.)
In the car I worked on, it is correct for some of the relays with the same part number to be installed 180 degrees out from the others.
Suggestion: When your HHR is running right, make a sketch or take a picture of how all the relays are arranged in your fuse box. That way, if you or somebody else scrambles the relays later, you can get back to a working configuration.
B) The relays in an HHR like to bounce loose a little. I'm not sure why - maybe the small terminal pins can't compete with the mass of the relay - but sometimes when opening the fuse box cover, you will see one or two of the relays sitting crooked. Pushing them down flat with your thumb fixes it.
I've never had one fall out and cause something not to work or work intermittently, but I have observed the relays being crooked when working on the car for other reasons. I don't think this is something you need to look for every day or every week - maybe every oil change would be a good interval. If you drive on a bumpy dirt or gravel road, or hit a big pothole, and something electrical suddenly quits working, it would be a good thing to check.
I haven't ever seen any of the mini fuses (all over the fuse box) or big fuses (along the back edge of the box) trying to back out - just the relays.
C) It's normal for your fuse box to be missing some of the fuses and relays for options your car doesn't have. (And no, buying and installing the missing fuse or relay won't magically make that option work, either.
)
D) It is possible to test all the fuses while they are installed. Each end of the fuse has an exposed metal bit on the top of the fuse. It helps to have a test light with a pointy probe, or a multimeter probe, or equal.
It is not possible to test the relays while they are installed. If you have somebody else around, you can have them sit in the driver's seat and operate whatever it is, and you can listen for the relay clicking in the fuse box. If it's something like the headlights where the relay comes on and stays on, you can turn the lights on at the dash, and then go to the fuse box and unplug and replug the relay to see if you can feel/hear it turning off and on. Just because it clicks doesn't mean the contacts are also good, but if it doesn't click and you *know* it's getting power to the coil, you can be pretty suspicious of it.
Some of the relays are the same part number, so you can swap them around to see if the problem follows the relay or not. But, beware of installing them backwards, as above!
E) If you take off the red wire(s) that live on their own stud on the side of the fuse box, note that the ring terminals aren't quite symmetrical. When you reinstall them, run the nut down most of the way, and then push the wires up against the side of the fuse box before you tighten the nut fully. Otherwise, the plastic cap that folds up over the stud won't seat all the way.
F) If you ever swap fuse box lids for some reason, make sure the directory inside the new lid matches the old one, or transfer the old one over. This may save you trouble on the side of the road some day.
G) The engine computer lives on the front side of the fuse box bracket, but its connectors are straightforward - they are the two connectors that are visible on the front of the engine computer. The engine computer doesn't have any other "hidden" connectors coming out of the sides or the back.
---
Donbrew... is that about what you wanted?
Truckette
And here it is.
---
Fourth, what I had to do to get the fuse box to work when putting it back on to the four big connectors.
On the first attempt at reassembling the car,we did it like I think they did it at the factory - all four connectors in the wells, slap the fuse box down, tighten the four bolts, done. When we tried the key, though, some things lit up when the key was in "run", but the starter wouldn't operate when the key was turned to "start". I also noticed that I didn't hear the fuel pump buzz for a few seconds when the key was turned to "run", and some things inside the car, like the heater controls, didn't seem to have power.
I poked around in the fuse box with a test light, and found that all of the hot-all-the-time stuff (circuit 30 in the old country) worked, but some of the hot-with-key-on stuff (circuit 15) wasn't getting power. I was playing with the "RUN/CRNK" relay in the underhood fuse box, which powers some of the hot-with-key-on stuff, and found out that by pushing the relay sideways with my fingers, I could get things to come on, but as soon as I let go, the power would go away again. When I swapped that relay with an identical one, the problem stayed with the socket (it didn't follow the relay), so I didn't think it was the relay.
I figured there might have been a problem with attaching the connectors to the bottom of the fuse box. I went to the back and disconnected the battery, and then went up front, loosened all four bolts, got the connectors loose, and lifted the fuse box off again. I inspected the harness connectors for cracked housings or bent terminals, but they were OK. I inspected the pins sticking down from the bottom of the fuse box for being bent or pushed up into the plastic too far (in other words, not sticking down far enough), but they were OK.
I decided to start a couple of the big connectors by hand. Because the harnesses come out of three sides of the bracket, it would be IMHO very difficult to start all four by hand. I left the back 2"x4" connector and the front left 2"x2" connector in their wells on the bracket. I then held the fuse box above the bracket and gently started the middle 2"x4" connector and front right 2"x2" connector on to the bottom of the fuse box by hand. I think I then started the bolts for those two connectors a couple of turns. Then I held the fuse box as level as I could, and gently pushed it down onto the brackets, to mate the two connectors that were still in their wells. It may help to wiggle the fuse box side-to-side and front-to-back a little as you push down, to help the connectors in the wells get aligned. I tightened all four bolts all the way, hooked the battery back up, and tried it.
Success! Everything inside the car that should have worked, did. I heard the fuel pump buzz when I turned the key on. I twisted the key to start and the starter ran and the engine started. I drove it 3/4 of a mile (1.2 km) to the gas station, and about 1.5 miles (2.4 km) back; everything worked, no trouble codes.
I don't actually know what was wrong or what I did to fix it. My best guess is that when we first slapped the fuse box down, we pushed some of the terminal pins on the bottom of the fuse box up into the box, so they weren't making contact, or only making intermittent contact. When I started the two connectors by hand, and then slapped down the other two, I think I didn't push any of the pins out of the way, so they all connected properly. I think.
Fifth,some other observations about the fuse box.
In the car I worked on, it is correct for some of the relays with the same part number to be installed 180 degrees out from the others.
Suggestion: When your HHR is running right, make a sketch or take a picture of how all the relays are arranged in your fuse box. That way, if you or somebody else scrambles the relays later, you can get back to a working configuration.
B) The relays in an HHR like to bounce loose a little. I'm not sure why - maybe the small terminal pins can't compete with the mass of the relay - but sometimes when opening the fuse box cover, you will see one or two of the relays sitting crooked. Pushing them down flat with your thumb fixes it.
I've never had one fall out and cause something not to work or work intermittently, but I have observed the relays being crooked when working on the car for other reasons. I don't think this is something you need to look for every day or every week - maybe every oil change would be a good interval. If you drive on a bumpy dirt or gravel road, or hit a big pothole, and something electrical suddenly quits working, it would be a good thing to check.
I haven't ever seen any of the mini fuses (all over the fuse box) or big fuses (along the back edge of the box) trying to back out - just the relays.
C) It's normal for your fuse box to be missing some of the fuses and relays for options your car doesn't have. (And no, buying and installing the missing fuse or relay won't magically make that option work, either.
)D) It is possible to test all the fuses while they are installed. Each end of the fuse has an exposed metal bit on the top of the fuse. It helps to have a test light with a pointy probe, or a multimeter probe, or equal.
It is not possible to test the relays while they are installed. If you have somebody else around, you can have them sit in the driver's seat and operate whatever it is, and you can listen for the relay clicking in the fuse box. If it's something like the headlights where the relay comes on and stays on, you can turn the lights on at the dash, and then go to the fuse box and unplug and replug the relay to see if you can feel/hear it turning off and on. Just because it clicks doesn't mean the contacts are also good, but if it doesn't click and you *know* it's getting power to the coil, you can be pretty suspicious of it.
Some of the relays are the same part number, so you can swap them around to see if the problem follows the relay or not. But, beware of installing them backwards, as above!
E) If you take off the red wire(s) that live on their own stud on the side of the fuse box, note that the ring terminals aren't quite symmetrical. When you reinstall them, run the nut down most of the way, and then push the wires up against the side of the fuse box before you tighten the nut fully. Otherwise, the plastic cap that folds up over the stud won't seat all the way.
F) If you ever swap fuse box lids for some reason, make sure the directory inside the new lid matches the old one, or transfer the old one over. This may save you trouble on the side of the road some day.
G) The engine computer lives on the front side of the fuse box bracket, but its connectors are straightforward - they are the two connectors that are visible on the front of the engine computer. The engine computer doesn't have any other "hidden" connectors coming out of the sides or the back.
---
Donbrew... is that about what you wanted?
Truckette
Last edited by RJ_RS_SS_350; 08-31-2020 at 09:42 PM.
10-24-2017, 08:32 AM
#3
Technical Moderator
Join Date: 01-23-2009
Location: Fredericksburg, Virginia
Posts: 24,688
Great, thank you!
Here is a video that, at least, give a visual. I'll try to find some illustrations.
BTW, automatics also have a TCM mounted with the ECM.
One thing that is common enough that there is a TSB about it; don't touch either of the computers with the positive cable from the fuse box; the metal boxes are grounded and will cook the electronics.
Here is a video that, at least, give a visual. I'll try to find some illustrations.
BTW, automatics also have a TCM mounted with the ECM.
One thing that is common enough that there is a TSB about it; don't touch either of the computers with the positive cable from the fuse box; the metal boxes are grounded and will cook the electronics.
10-24-2017, 08:20 PM
#6
Moderator
Join Date: 05-01-2014
Location: California
Posts: 7,804
Wow, that really is a great write up!! Really interesting about the relays. We've had some members say they checked the relays, for various issues, and they were fine. But I wonder if they were backwards? Hmmm.....
08-31-2020, 09:37 PM
#8
Moderator
Join Date: 05-01-2014
Location: California
Posts: 7,804
I found the discussion we had about this.
https://www.chevyhhr.net/forums/www....ad.php?t=61832
The OP has now been edited.
https://www.chevyhhr.net/forums/www....ad.php?t=61832
The OP has now been edited.
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