medx421

Hello,

I also posted this in the Z71 forums, where I did recieve some good suggestions. I am just looking for other opinions as well as someone in this forum may have dealt with similar issues.

Last year I purchased a used 2004 suburban Z71. I love the ride, however since I bought it, very few of the guages light up. Actually the only thing that lights up (backlighting at night) is the speedometer cluster and the stereo. The climate controls, overhead climate controls, steering wheel buttons, 4WD switch, headlight switch, and rear wiper switch do not backlight at all. Reading through various forums, I learned that this was largely attributed to a bulb problem. Accepting that fact, I went in search of parts. First I bought used parts, only to find that they to did not illuminate. Recently I purchased new OEM replacement parts, only again to install them and have them not work. I have checked all the fuses which appear to be fine. I am not extremely savy with wiring diagrams, but I can follow one around if I had one. I can also follow wires around pretty good. I'm convinced this isn't a bulb problem, but a deeper electrical problem. Can someone point me in a direction to start looking for wiring and electrical problems that may be causing all of these outages. Your help is definitely appreciated as I am pulling my hair out.

Nick

legolas894

I think my truck is similar. The 4WD lights have a mind of there own. If you push the area around the switch, the lights come on. I've taken the dash bezel off and reseated the wires, and they still do this. The dome lights stay on even with the key on. This is a short in the wiring harness up in behind the dash. I can wiggle it around and it will go off for awhile. If you jiggle too much, the power locks "unlock". The headlight switch is no longer illuminated. The compass no longer displays the temperature and the radio has only a few buttons lit up.

I think it's really just shoddy components. If you pick up a used part, it probably has the same issues as your current part.

I broke the door handle a month ago and just replaced that this weekend. The seat was broken and would rock like a rocking chair. I fixed that by bolting a new piece of metals to the support and seat.

Now, one of the door lock levers isn't unlocking the door! Don't get me wrong-I like the truck and the capacity etc. Just hate the crappy parts and assembly.

Man!! I have a 1967 GMC with a lot less issues and all almost original equipment!

medx421

As an update. I got a chance to really get into it tonight. I had the luck of having a func,ional 03 Silverado at my disposal, and later on a friend with a Tech2 scanner. I pulled the headlight control switch w/ dimming wheel out of the 03 and put it into mine. It did not work. Additionally, just to check the quality of the parts that I ordered, I put the HVAC controller into the 03 and it worked fine, backlighting and all. Later when I was able to scan codes, I think I recieved some pretty bad news. It spit out the following codes:

B2610 - Passenger Compartment Dimming 1 Circuit
B2615 - Passenger Compartment Dimming 2 Circuit
B2625 - Display Dimming Pulse Width Modulation (PWM) Output Circuit

This all seems to stem from the BCM2 module. So, I guess, where do I go from here? Do I need to start looking for a whole new BCM, or is this repairable on another level? We tried clearing the codes only to have them immediately return. The B2610 was the prevalant current code while the 2615 and 2625 were in the history codes. Thoughts?

Nick

legolas894

I wouldn't rule out wiring shorts. That BCM is incredibly expensive. I had thought the same thing with my courtesy lights staying on so I got a quote and it was over $700 for that part. That made me look a lot harder and I know I have a short-just hard to get at.

Good luck. Great to have friends with the gadgetry.

73shark

Sounds like the codes are telling you that it's in the wiring.

medx421

Well one could hope (or not hope) that it is. I'm a little above my head now if it gets into finding shorts or faults. I can replace the BCM, but like you suggest, who's to say that it doesn't immediately happen again afterward due to wiring.

Nick

T-bone

I have this same problem with my 2005 Z71 extended cab. The steering wheel lights only half work, 4 wheel drive lights half work and the CD player has now gone out. This started shortly after I bought the truck brand new. While under warranty (<36,000 miles) I had the CD player replaced twice, and HVAC switch replaced twice and a speaker in the drivers side door. Now since it's out of warranty (94,000 miles) I just live with these lights going out. I do believe it's a short because if I flick the dash around the healight and 4 wheel drive buttons the lights come back on sometimes. I don't like tearing into the dash though if I don't have to. Let me know if you find a fix for this as I have a friend with a 2005 and the same issues so it seems to be happening a lot.

Blaise614

I also have a Tahoe I just replaced all the mini bulbs in all the components and it fixed them all u can get the bulbs on eBay just look up Gm mini bulbs and u can start changing them easy with soldering gun and a solder sucker for about 30.00

Hrpchr

I recently purchased a 2004 Suburban Z71, and have similar "partial" backlighting of steering wheel buttons and HVAC controls. From reading I have done here and elsewhere, it seems that the two Dimming Circuits are responsible for some mysterious combination of different bulbs on different panel sections.


The PO installed a Jensen VX7020 stereo, and I wonder if connections made to wiring, maybe lighting wiring in the dash, is creating some imbalance or floating ground or power-to-power short. The Dimmer Circuit error codes may be from the altered wiring.


I think the BCM is reporting the problem in the two wiring circuits in the example above, and is not a diagnostic of the Body Control Module itself.


I wonder, how many GM mini-bulbs have to blow (fail open) before the BCM sets an error code for that circuit?