Tachometer won't zero
 

I have a 2007 and about a year ago our tach started acting funny. The needle moves with the RPMs but it will not reset to 0 when you shut the car off. Now when the car is turned on my tach shows about 5000 RPM at idle and goes up from there until the needle is off the range of numbers until it is almost pointing straight down. It does move as I speed up or slow down but it is obviously not right.

I can sit there and turn the car on and off about 20 times (without starting it) and it will eventually go back to 0 but once I start it the tach never goes back to zero when I turn it off.

Any ideas?

I haven't heard of that one before. Have you had any other issues recently or about the time the tach started acting weird?

You can try disconnecting the battery (negative post only for safety reasons) for about a half hour - it might reset things, but no guarantees, but it's worth a try.

X2, the old battery lobotomy has worked wonders before!

Then check the grounds

https://www.chevyhhr.net/forums/how-...cations-56504/

I am going to be doing some maintenance on it in the next couple of weeks and that might be a good time to try the battery trick. I was going to put in some new plugs, K&N filter, headlight bulbs, and wipers so that would be a good time to disconnect the battery.


I will give it a try. Thanks

Please remember, AC Delco 41-103 iridium plugs .

I picked up a set of NGK Laser Iridium plugs at the tune of about 8.50 a piece. These are supposed to be the best you can buy. I sure hope these are good enough.

This is the etirety of what the Shop Manual has to say:

Yeah, no, it never goes to 0 RPM. I took the car out today and it is no longer even moving and it is pretty much stuck pointing straight down. I am not sure if the battery thing will even work. If I physically move the needle by hand will it damage the tach? I suppose no more than it already is. Would that possibly indicate a short on the wire that goes to the tach?

Where does the wiring harness go from the gauges? All the other gauges, lights, and displays work on the dash so maybe it is just the one wire controlling the tach.

That's what "serial data" means.

Hmm. Almost sounds like the tach needle is loose on the shaft. Don't be surprised if it just falls off.

I am going to take it apart to check all the connections and I will check to see if the needle is loose.

Yea moving outside of it range it probably stripped the tiny little gears in there. Or, ECOtec kicked in yo! You have a one of a kind 10,000 RPM redline! Eat that SS. Grab a junker or search ebay for a cluster!

I have looked into getting a used one but there is no guarantee that they are interchangeable. I talked to several dealers and they want $600+ to replace it.

They said I could bring in a used one to have them re-program but they have to take out the old one read the old one and program it to the used one but could not guarantee that it would work. To do that the dealers want $190. to re-program and $190 to take out the broken one and put in the re-programmed one.

Give me some time to be sure, but I think your dealer is blowing smoke. I am firly sure that the I/P is plug and play, all of the data is stored in the BCM.

X2 on that. The odometer reading and such are stored on the "black box" IE the BCM. Plug and play. Almost 100 percent sure.

I just finished reading the entire article. The VIN has to be matched for the odometer to display, otherwise plug and play. So they usually charge 1 hour labor for the computer work, but theses days other shops have the tools to do it.

Hate to tell you this, but my 2007 did exactly the same thing, but fortunately while the car was still under warrantee. Apparently as I recall the 2007's use something of a different gauge cluster than other years, but the fix was replacing the entire cluster. No problems with it since. BTW it took them less than a hour to do it, I waited while they did the work. It did take 3 or 4 days for them to get it, had to be ordered.

Ive been down this road. You can put a used one in but your odometer and trip meter will not work. Spent a few Months trying to swap a used one in my car. No one in the North West could or would (including the dealer) reprogram a used instrument cluster. If you purchased a new one, they could program it to your car vin.
Visit, New speedo now back doors don't work.
If you find someone that can reprogram a used cluster let me know.
Good luck.

I can't find the article again.
Evidently it is the panel that needs to have the VIN inserted, so that it matches the VIN in the BCM.

Maybe it's like a new radio that is programmed to grab the VIN as soon as it's plugged in. I will bet that the technicians just don't know how to do it, like the one I had that didn't know how to program the air bag module.

The tech2 site says that any module can be programmed via the SPS (Service Programming System). The dealer may be under the impression the mileage is stored in the cluster like many other cars, changing that mileage can be a bit tricky legally. However, in the HHR the mileage is stored in the BCM, and can be extracted with a Tech2 or similar.

Changing the odometer reading is a legal thing, most cars have the odometer data stored in the instrument cluster.

Here is a TSB, the HHR is listed as a IBCM system

One place I read that the IPC retains the last reading that it got from the donor car BCM. When that reading does not agree with the stored reading the odometer will not work. The fix is to reprogram the BCM from tisweb.

This thread from Snap-On forum is confusing, but contains info. GM BCMs, Instrument clusters and milage - Snapon Diagnostics Product Forums

I did find a guy locally that said he could program the HHR gauges. This really hasn't been a priority because it hasn't effected the car but it sure is annoying. He said he could program my VIN number and change the odometer reading into a used one. He also has cloning capabilities for the gauges so maybe that is the way to go to make sure everything is the same on the two different gauges. I think to clone the gauges they have to be the exact same part numbers.

Before I share his name I want to make sure he can do what he says he can do. I still want to take the old one out first and mess with it and get the part numbers.

Well I finally pulled the gauge cluster to get all the part numbers off of it. I first disconnected the battery and decided since I had it out I would see if I could see anything obvious with the tach. I moved the needles around to see how they felt and the tach needle felt just like all the other needles but it sounded like it was dragging on the face of the gauge. I went a head and disassembled the the entire gauge cluster and looked at the circuit board and didn't see anything obvious. I checked to make sure the soldered joints on the stepper motors were good and they looked fine. Not finding anything I put it all back together making sure that none of the needles were dragging on the faces.

I put it back together, connected the battery and sure enough it was working like a dream. It has been over a week and it is still working so I am keeping my fingers crossed.

Conclusion: Either unplugging the battery while I was working on it reset everything or the actual needle was dragging on the face and the motor wasn't strong enough to overcome the drag. Personallly I think it is the later of the two as the further around the needle got the more drag it had which would explain why it got stuck way off the gauge.

Well I will keep you posted if anything changes.

Thanks for all of your help.

That's great that you got it fixed up, must have been pretty annoying. Thanks for updating your thread, may help someone in the future.

Yeah!! Fixed, and thanks for confirming the fix.
Tearing it apart checking it out and trying something, instead of jumping on the old Internet and just buying a new gauge cluster.

Interesting. So was the needle or shaft somehow slightly bent causing it to rub the gauge face ?
Or could the gauge face have somehow warped up a little behind that needle.

Over the years I've had several gauges with warped faceplates on some air tool equipment. In fact, I've got one on a compressor air line at work right now. Needle won't register past 30psi (150psi supply) but since the golf cart tires only take 22psi I haven't bother to fix it.

The shaft of the motor was fine but none of the gauges are exactly centered in the holes on the gauge face. They are close but not perfect. The needle has a small clear tube if you will that slips over the motor shaft and then you press a little harder and the shaft goes into the needle base. The clear tube is how it gets the light up to the needle. I think the problem is on the bottom side of the needle in the center it is cone shaped and it is what was rubbing on the hole in the face, not the actual end of pointing needle. I just made sure not to press it in so far that it rubbed. It took me two or three times to get it right because you have to put some pressure on it to get it to go and a couple times I pushed it in too far. It is still working so I am happy if that is all it was.

I will tell anyone attempting this that getting the gauge panel out has it's challenges. And you cannot get to the back side of the gauges from under the dash. There is an interior clip on the top back of the gauges that goes into a slot in the dash and it is a booger to get loose. Then they have that funky wire connector that goes into the gauges. It is not for the faint of heart.