08 lmm won't turn off, erratic wiper blades, brake light and abs on - Chevy and GMC Duramax Diesel Forum
07.5-10 LMM Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #1 of 4 (permalink) Old 09-12-2018, 10:47 PM Thread Starter
Join Date: Sep 2018
Posts: 1
08 lmm won't turn off, erratic wiper blades, brake light and abs on

so went to get out and turn the key and take it out, truck wouldn't turn off and the wipers start going. switch was off. after I manually shut down the engine, abs and break lights now illuminated. the issue is intermittent. was okay for awhile but I went to the truck for my bag and shut the door which somehow made the wipers start going and my lift pump run. also remote start may or may not work and when it does the start just turns and turns till I key it on in the truck.....SO wtf haha I started by checking fuses, all good. I checked the grounds near the filler neck and by the front fender, I cleaned them up, and even ran 10 gauge from the rear to front to negative terminal to ensure I had a good ground. My cruise isn't working, bad circuit a code is on, reverse cam now won't work, and for awhile the check trailer controller has been going but thats been that way for 6 months. I have amp boards, efi, head studs and gaskets, full delete, 6" lift, 150 birddog raptor, intake. none of which is newer than 6 months if not years old. I have an edge but its just used as a gauge screen for get and boost. Im sure some will assume it the edge, I pulled it out and the issue persists, I reset efi, eco, etc. my batteries ill have tested tomboy tho they are 5 month old interstates, I d have a JL system and head unit from Kenwood. SO at this point im assuming the ignition switch which im getting tomorrow or I have a chewed, split, worn wire somewhere thats creating positive flow not enabling the truck to shut down, ground out, etc . bad ecm. or bad grounds else where
1. change ignition switch
2. check remaining grounds
3. check and track wiring(FML)
4. Replace the relays in fuse box
5. Replace ECM, tho my truck is running great and the efi dsp5 shifts tunes
6. Replace PCM, maybe idk
7. Let her slip down the boat ramp sunday........

Anyone have this happen to them, any ideas, etc? im all ears if u think im wrong. Really have no idea what the issue is
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post #2 of 4 (permalink) Old 09-13-2018, 05:03 AM
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Join Date: Oct 2016
Location: Maurice, LA
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The problems being intermittent and a mere closing of a door causing activation of wipers sounds like a short to me..................but where, I have no idea.

Others on here more knowledgeable than me may have some ideas though.

One question though, how old are your batteries? I do know that low voltage can cause all sorts of weird symptoms.

2008 Silverado 2500HD CCSB LTZ Diesel
FASS 95 Lift Pump (with Baldwin filters), Edge Insight CTS Monitor on a Windshield Mount, Nicktane Fuel Filter Adapter w/ CAT 306-9199 UHE tertiary fuel filter, Bilstein 5100 Stock Height, Bushwacker Bed Rail Caps, AMP Research Bedstep, Fumoto oil drain valve, Dorman PS Oil cooler, Pioneer AVIC 7200NEX GPS/Stereo, Air Lift LoadLifter 5000 Air Bags.
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post #3 of 4 (permalink) Old 10-17-2019, 08:57 PM
Join Date: Oct 2019
Posts: 1
Did you ever figure out what was wrong with your truck? Mine is doing the same thin.
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post #4 of 4 (permalink) Old 10-18-2019, 01:13 PM
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Join Date: Aug 2009
Location: Berryton, KS
Posts: 1,337
What aftermarket devices have been wired into the system? Radios and cigarette lighter circuits are always my first suspect.

Another suggestion to troubleshoot is that when the problem occurs, start pulling fuses to see if any stop the problem, make note of the fuse number and description then get an electric wiring chart and see what is on that circuit that might be contributing to the problem.

Ron Nielson
2008 Silverado LT, CCLB, Edge Insight CTS
2009 Arctic Fox 29-5T, Silver Fox Edition, Onan 3600 LPG generator
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