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Gauge cluster not zeroing out 2008 lmm

717 views 6 replies 3 participants last post by  Chasevandeest 
#1 ·
Can’t seem to find a similar issue to mine anywhere, a few of my gauges get stuck in particular the volts is always the first one, but could be gas gauge or any other gauge except tack and speedo. No codes, have tried to pull them several times. have checked ground strap under hood looked through a few fuses and taped a black wire that was rubbed through. The DIC and shift indicators go out and that’s when they start to stick and will eventually max out unless DIC and shift indicator turns back on. Once it does they still don’t zero out but don’t get stuck any farther. The shop that rebuilt my cluster is saying that it has to be a wiring issue because it’s the same issue I came to him to fix then started up again 3 days after repair. one day it had a loss of power seemed like trans was confused and then “popped” back into first and didn’t sound pleasant. But has only done that once. Have no clue what it could be GM was no help at all. If I disconnect the batteries and reset it , it’ll act fine until it’s next episode of bs. Hoping someone has gone through this and can point me in the right direction, bought the truck a 2 weeks ago and didn’t start this until last Friday. Has tbc fault and park sensor and tpms light on DIC. Has aftermarket head unit speakers and amp steps if that could have something to do with it. Tested the alternator at oreillys and it tested good but shows it’s age under the hood. Also believe i have the factory batteries in it but no slow crank and no drainage of them. Has gotten a lot worse since the dude supposedly “fixed” my dash just at a loss. Don’t want to point fingers but could the cluster still just be bad and the shop didn’t fix it properly?
 
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#2 ·
Welcome to DieselPlace

Have you removed your batteries and taken them down to your local auto parts store for Load Testing?
Individual load testing can determine if any cells are bad in the battery.
bad cells can cause strange electrical gremlins to appear
 
#4 ·
When you attempt to pull codes, does the scanner tell you that there are 'no codes found', or is it more like the process just doesn't complete? Does the scanner give you any other information?
 
#5 ·
Scanner is $350 bosh scanner it says no codes found. After I got the dash rebuilt I had a code for it being a open circuit because I drove it and when I cleared it there where was a tcm code but didn’t think anything of it and cleared it and no codes have come back
 
#6 ·
My totally wild ass guess is that you have something that is pulling your GMLAN down from time to time OR you have an undiscovered short of loss of ground somewhere. Testing of the GMLAN is not particularly complicated, but it takes some relatively expensive tools - a DLC break out box and a scope and access to accurate wiring diagrams. The breakout box gives you easy and direct access to the GMLAN and the scope lets you see the waveform for the GMLAN. Lots of Youtube videos on this subject. Or, you could find a shop that specializes in auto electric/diagnostic repairs and already has those things. Not everyone lives near one of those shops.

Before I did anything , I would remove the aftermarket head unit and the amp steps from the circuits and see if any improvement. Always best to get the truck back to it's original configuration before trying to solve problems.
 
#7 ·
Tested the batteries today and they both tested good. Truck did something weird today where when the DIC and shift indicator where off I turned my heat off in the truck and at the same time the DIC and shift indicator turned back on. Hasn’t turned off again , the gauges are slowly fixing themselves again. Anyone else have any suggestions before I take it to a car electrician? Also while digging around yesterday failed to mention it looks to have a non oe engine harness said delphine I think. Just want to confirm that’s not what they came with from factory also has a slice for 2 wires they are orange and pink on those two connectors and some of the case of the butt connector is rubbed off but it doesn’t seem like that’s where my short is after wiggling it around. Starting to think this is going to be more costly than I expected.
 
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