No crank, no start, no communication with ECM, no power/voltage drop — Buick Lucerne 2006

[samronald]

Some time ago I bought an old Buick Lucerne 2006 (85k miles) as a project car. The seller said that the car is totally fine because the GM service run diagnostic, it only needs new ECM to be reprogrammed. It was definitely a pig in a poke but I bought it for really cheap so it was worth a try.

What is the problem?

New battery, no crank, no start, no communication with ECM, a lot of shorts on different electronics around the body.
As soon as battery connected, the voltage drops from 12 to 5-6 immediately. No power to the fuse box under the hood.

What did I do to investigate?

1. I checked mostly all grounds, including the ones for the bcm under the passenger seat, cleaned corroded ones, and replaced screws for them. I didn't reach for the ground somewhere behind the engine though.

2. I've tried 2 different ECM and 3 different BCM. No luck there.

3. I replaced all the fuses and tightened the fuse box under the hood. It sorted out all the "shorts" which were showing on the scanner before. No big luck, but at least something.

4. I disconnected all the electronics which are known for parasitic draws — overhead lamps near sunshades; 2 front doors (they were weirdly ticking for some reason); alternator (because it's connected to the battery directly); the dimming switch on the left side near the steering wheel; the full glove box. The main harness under the hood seems to be getting power but still no luck.

5. I powered up the battery with a jumper, drain was still there but at least I could scan for codes one more time after all the manipulation and these codes are still there:

B3600:03 — Passenger compartment dimming request signal circuit low voltage

(Which is weird, because I disconnected it, but I have to check it one more time)

This code is for most of the systems — engine electrical, automatic transaxle, anti-lock brake system, BCM, body rear end, park brake.

The other one is B1001:00 — Sensing and Diagnostic Module (SDM) option configuration error. (Under the category: supplemental inflatable restraint)

*These codes are left only because of my manipulation with the jumper. I've attached the original PDF with codes list when I have only 5v on the battery. It's just to see the difference with all of my manipulations.

My questions:

1. I have an Autel Maxisys MS908pro, I believe the tool can reprogram both ECM and BCM to match the VIN. Am I right?
2. What do I do next? Where should I look next? Get under the car, disconnect the starter, check that one last ground and check the main positive cable? Ignition switch fault maybe and I need to replace it?
3. I also have 2 grounds stocked on each other on the transmission on the right side. Is it ok? I've read that it is ok, if they sit tight with no corrosion or paint.

Please give me some help and sacred knowledge on this Buick. I have no idea why ECM is not powering up as well as the main fuse box.
I'm not experienced with car electronics so if you can provide detailed suggestions and explanations, I would really appreciate it. I'm open to try any ideas and I would be glad to clarify anything if I missed something describing the issue.

Thanks in advance.

 

[2007LucerneCXL]

These are best guessing as it could be one or many items. The actual under hood fuse box itself, rear seat fuse box but note the year doesn't have the fuel pump issue which is 08 and up.
The ECM harness may have a short or damaged pins.

As on troubleshooting one method is to pull fuses while watching the meter until the voltage returns to normal. The next option is disconnect modules and watch the meter.

 

[samronald]

These are best guessing as it could be one or many items. The actual under hood fuse box itself, rear seat fuse box but note the year doesn't have the fuel pump issue which is 08 and up.
The ECM harness may have a short or damaged pins.

As on troubleshooting one method is to pull fuses while watching the meter until the voltage returns to normal. The next option is disconnect modules and watch the meter.

Hi! Thanks for the response.

I did this already, both the fuses and module methods. No changes on the meter.

I also think this could be an issue where the positive cable damaged somewhere under the hood and touching the body. I need to inspect this closely.

 

[2007LucerneCXL]

The wildcard if the vehicle had/has the heated windshield washer fluid. It was recalled and the repair was the removal, some were done properly and others had a slash and burn method. Passenger side by the firewall if still there. Electrical gremlins over the net is difficult at best, good luck on the project and getting it resolved.

 

[samronald]

The wildcard if the vehicle had/has the heated windshield washer fluid. It was recalled and the repair was the removal, some were done properly and others had a slash and burn method. Passenger side by the firewall if still there. Electrical gremlins over the net is difficult at best, good luck on the project and getting it resolved.

Thanks! Just checked the recall bulletin, I'll looking into that.

 

[WalmartTech21]

I can likely explain the B1001; you've mentioned that the BCM has been replaced 3 times; B1001 only sets when there is a VIN mismatch in either the BCM or SDM or the 4 digit primary data key stored in the SDM doesn't match with the BCM (which will happen if there is also a VIN mismatch.) the only way to clear it is to reprogram the BCM with the proper VIN and Primary Data key.

EDIT: the conditions for setting the B3600 is if the BCM detects an open circuit or a short to ground in either the I/P dimming 5 volt reference circuit or the corresponding signal circuit.

 

[samronald]

I can likely explain the B1001; you've mentioned that the BCM has been replaced 3 times; B1001 only sets when there is a VIN mismatch in either the BCM or SDM or the 4 digit primary data key stored in the SDM doesn't match with the BCM (which will happen if there is also a VIN mismatch.) the only way to clear it is to reprogram the BCM with the proper VIN and Primary Data key.

EDIT: the conditions for setting the B3600 is if the BCM detects an open circuit or a short to ground in either the I/P dimming 5 volt reference circuit or the corresponding signal circuit.

B3600 seems to be the main issue. I've got to the point where I was testing all the fuses again and as soon as I inserted the fuse for instrument panel harness module, the voltage dropped from 12 to 5. And also it drops when I turn the key in accessory mode.
It either the cluster panel because the fuel gauge is not working or the ignition switch. Maybe both, need to test further. Like you said — corresponding signal circuit.