Scan code help

[jimmackey11]

Let me preface the codes question with some history. A couple of weeks ago, I was sitting at a stop light in broad daylight and I noticed the daytime running lamps suddenly turned off. All the other lights were working fine but no matter what I tried I could not get the headlights to come back on. The next day everything was fine. Didn't think too much about it until the other night when, at night, I was driving on the interstate and the lights went out again. Again all of the other lights were fine and I had to turn on the high beams to see. I've also had some random driver side door lock issues where that lock only will not open or close with the remote, but all other locks operate just fine.

So I took my 04 Envoy to my mechanic and he checked for the codes and he got two:
B2575
01162

The B2575 looks like, from researching the site, could be a ground to the BCM or a bad BCM. Any other ideas welcome!

The other code is a mystery. All his computers and tech tools say that code is "undocumented", and I can't find that code on anything I search. Does anyone have any ideas what that code might be?

I appreciate any and all assistance! Thanks, Jim.

 

[Mounce]

For the headlights going out that's a common issue. Your relay is starting to go bad. If you replace it, make sure you only use ACDelco. Aftermarket brands are well known for overheating and melting the fuse box. It's a solid state relay so it'll probably cost a little more than you would expect but they can be had online for under $30.

http://pages.ebay.com/motors/link/?nav=item.view&id=161413298046&alt=web

 

[Mooseman]

For a quick check, you can swap the headlight relay with the one for the cooling fan. Same relay. If it cures the headlights but now your fan is whacked, replace it. If you have a pick-a-part nearby, grab some there cheap.

 

[jimmackey11]

Will give those ideas a try later this week.

One update/correction - that second code I listed is actually U1162 (supposedly the "U" stands for "undocumented"?)

Also wanted to ask, with all these strange electrical issues do you think the BCM is going bad? What would be the deciding factor to go ahead and replace it or not?

 

[Blckshdw]

I wouldn't suspect your BCM needing replacement yet. As previously mentioned, the headlight issue is common enough, that we know it's usually the relay on it's last legs.

I had the same problem last fall with my passenger door exhibiting the same behavior. Ended up being the door lock solenoid. Having to reach over and manually (un)lock the door was quite annoying when I had passengers. After replacing that, all was right with the world again.

Edit: Of course, checking and tightening your grounds is a quick and easy troubleshooting step.

 

[coolasice]

DTC U1162

Lost Communication with

Audio Amplifier, BCM, IPC, PRM

Very likely a bad ground

 

[Mooseman]

Or a loss of communication:

Info on these U codes is sparse. I found this which is more specific to our platform:

http://www.autowebrepair.com/forum/upload/showthread.php?tid=5911

On the U codes the last 3 digits are for the module. The U1162 is for the Liftgate Module. The U1000 is a lot more complicated. It moniters the modules and if it can not isentify a critical parameter within 5 seconds, the U1000 is set. Here are the modules monitored----

Audio Amplifier, BCM, HVAC Control Module, HVAC Control Module-Auxiliary, IPC, MSM-Driver, MSM-Passenger, PCM, Radio, SDM, TCSCM, VCIM, VTD

So liftgate module may be at fault. Anything controlled by it not working, like the remotes?

 

[coolasice]

DTC U1162

Lost Communication with

Audio Amplifier, BCM, IPC, PRM

Very likely a bad ground

Loss of comms with liftgate module.. Possibly a cracked wire in gate boot

 

[jimmackey11]

So liftgate module may be at fault. Anything controlled by it not working, like the remotes?[/quote]

Yes randomly the lift gate latch (when you open or close the lift gate that sound it makes like a lock or something is opening) sometimes doesn't make that latching noise on open or close or when you unlock or lock with the remote. It doesn't affect the LG working. And just in the last couple of weeks randomly the driver side door lock hasn't been unlocking with the remote but will with the button on the arm rest.

 

[Mooseman]

You should check the wires in the boot in the liftgate. They have been known to fail inside that boot. And since it is intermittent, it would make sense if a wire is frayed inside the insulation.

 

[Mounce]

Mine makes a locking sound when opened and when closed so if yours just randomly makes the sound there's likely something going on.

Follow advice above about checking the wires. If you don't see anything, grab the wire at each end that you can reach and pull apart, if one snaps, there's your problem. Sometimes they break internally and they'll look just fine to the eye so it's necessary to do the pull test but even that ain't bullet proof.

 

[jimmackey11]

I've repaired a couple of the LG wires previously. Just finished checking the LG wires and everything looked good. So, I tried the snap test idea and low and behold one wire was indeed broken. Since the problem was random to begin with I'll just have to wait and see. Also got a new relay for the headlights, installed that and everything has been working OK but that too was random so just have to keep a close eye on everything and see how it turns out. I really appreciate all the advice!