2009 2.2 LS Panel

I am not the first person to attempt the repair on the vehicle, so I can only give you facts as I experience them.

Battery was at 8.22V so I charged completely.

I see no aftermarket devices on the vehicle.



Came to me with a "donor" ECM in place and a no crank condition. Scan revealed:
Present DTC
B138-04 Device ignition accessory circuit open
U2105 Lost communication with ECM
U2106 Lost communication w transmission control system
History codes
B1517-5A Battery Voltage Plausibility Failure
U2125 Lost Communication w Mobile communication control system
U2129 Lost Communication w remote control door lock receiver

I have no communication with the ECM, so I cannot view DTC there if any present.

I removed the donor ECM and replaced with original unit and scan revealed same results.

Checked for voltage on both sides of every fuse in under hood box w key on and battery maintainer attached
Fuse # 33 EXH 10 amp has no voltage either side
Fuse # 33 ECM 20 amp has no voltage either side

I then removed the top of fuse panel from connectors and inspected for evidence of damage. I saw what looked like perfect conditions on both the male upper half and female connectors.

I measured resistance from pin 6 to 14 at port under dash and verified that it was 60 ohms telling me both resistors were still in line.

After a lunch break I came out and turned key to on position to find no dash lights, auto headlights, or radio. Verified battery and maintainer were properly attached. after about 10 minutes of me doing nothing to the vehicle or touching it in any way, the condition reverted to conditions at top of this post.

I then scoured the vehicle looking for a ground or power issue. I moved all harnesses I could trying to reproduce the power loss issue or improve communication to/from ECM all to no avail.

Contacted the owner and was told the vehicle battery went dead and it was jump started to trigger this situation. Assures me the cables were never reversed. I am aware of the issues these vehicles suffer from after a jump and have flashed ECM and replaced remote door lock receiver modules to cure TPMS and key fob issues from the jump starts. But this is a new one to me. I am not electrically trained. My wheelhouse is engine mechanical. I remove rebuild and replace Ecotec engines here in Las Vegas and am comfortable diagnosing engine issues all day. ECM is my crutch with my scanner for all the clues, but without that aid I am woefully outmatched.

I researched some diagrams for power wires and what I see shows me that if I have power to other fuse locations, I should to those 2 that do not also. By that I mean, I interpreted the data I saw as if it was a power feed issue, the box would have several other dead circuits. I feel that a module(s) that regulate power to these is denying it and that's what I need to track down.

How can help this owner? I am too embarrassed to tell you how long I have spent to provide you with this info due to my ignorance, nor do I plan on charging the owner for my lack of knowledge and extra time dedicated to it.

Any help is greatly welcome. Any other info needed, please ask.

Thanks in advance from sunny Las Vegas

 

Seems to be a problem with the the BCM no communication . I trust you went throughout all the ground wire locations and all are good and tight and clean.
the jump start was at the battery in the back of the car or under the hood ?
Did you check the current sensor on the ground wire back by the battery?

 

Have you tried a different battery ? From what I read, the 1st owner had problems with a dead battery and now you've charged that same battery(?) and still have problems.
Try a different battery and see what happens.

 

Hook an Ohm meter up between pin 6 and pin 14 on the DLC . it should read 60 ohms, if not the GMlan is mucked up and you can narrow it down by checking each module.
There are tons of youtubes on the subject "can bus" This one is basically what I said.

 

BCM has no communication issues. I can access it consistently with my scanner. The BCM is still actively providing DTC as well allowing me to clear current and stored DTC.

The battery has been removed tested and replaced. It is known to be good. I have used another battery from a running vehicle with no change to situation.

The vehicle was jump started directly to the battery I assume, as all of the rear floor panels that conceal the battery have been removed and are still stored in a way that allows access to battery.

The clamp on the negative cable at battery... No I have not done anything other than inspect that the ground is secure and not corroded. How do i troubleshoot this clamp assembly? Are my symptoms in line with this part being damaged?

Another update is that a running HHR "loaned" its ECM to the disabled HHR with no change (not that I expected it to with no power to the ECM). But also the donor ECM was not damaged by being installed in this vehicle and still operates its original vehicle flawlessly.

 

If that was a response to my post you completely missed the point.

 

donbrew it was not in response to your reply, I only just saw it. The YouTube videos I watched explained that system has 2 120 ohm resistors and they are in parallel for a resistance of 60 ohms. If I see 120 ohms one of them is not present. I am certain I have 60 ohms.

If this is not correct, please explain or provide a link to a video that shows the 120 ohms as the desired value

 

Have the ignition related recalls been performed?

 

This is one of the videos I watched to try and learn. It is for a Silverado rather than HHR, but the system is similar from what I can read.

 

RJ

I have confirmed with GM that the vehicle has had all recalls completed and there none open.

Thanks for the idea