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Wont start "Chassis control module"

Bmcghan09

By Bmcghan09
in Troubleshooting & Recalls

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BlaineBug Enthusiast

BlaineBug

Posted
Posted (edited)

So it wasn't about the LED bulbs after all?  That's good to know.  Tens of thousands of people have upgraded their exterior to LED lighting with no issues.

EDIT:  I'm assuming the issue has returned once again even though the dealership switched out your LED bulbs after blaming them for the initial failure.

Edited by BlaineBug
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Bmcghan09
Bmcghan09

Probably should put a transmission too huh?

Bash74
Bash74

So what did the dealer say it wasnt communicating too. For instance, I had a no communication fault (U1556) but it was for the trailer brake module not communicating. This didnt stop the truck from be

BlaineBug
BlaineBug

The same thing was suggested to me about a bad battery and just go ahead and replace it anyway.  I had it checked three times by three separate auto parts stores, and on the third try I actually took

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Bmcghan09 Enthusiast

Bmcghan09

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It seems LED bulbs are a toss up. I think quality of the bulbs matters as well.  I’m currently riding dirty and don’t have any bulbs in. I was afraid to touch it. My entire truck was switched over to LED by the previous owner.  My license plate screws touch the harness so I’ll pull that down when I get time. There’s no fuse either. Seems like they are part of the BCM circuit which doesn’t help much. 

BlaineBug Enthusiast

BlaineBug

Posted
Posted

They probably are a toss up.  But obviously they aren't the problem here in your case.  Strange!  It's ridiculous that a short in the lighting wiring circuit would stop the main vehicle functions from operating.

swathdiver Senior Enthusiast

swathdiver

Posted
Posted
15 hours ago, BlaineBug said:

They probably are a toss up.  But obviously they aren't the problem here in your case.  Strange!  It's ridiculous that a short in the lighting wiring circuit would stop the main vehicle functions from operating.

Unless the short is bad enough to lower the vehicle's voltage past a certain point to where the computers/modules won't work.

Bmcghan09 Enthusiast

Bmcghan09

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Yeah, it’s insane there’s no limp mode or anything. Im disappointed in the engineering. Only good news is I think it’s the back harness. I’d rather pull that harness vs the front. The dealer said that even a little bit of feedback will shut down the module. 

BlaineBug Enthusiast

BlaineBug

Posted
Posted (edited)

If a system is to be so complex, where in the heck are the fuses, or total circuit isolation?  Redundancy to ensure vehicle functionality if an issue arises?  They missed those features?

Edited by BlaineBug
Bmcghan09 Enthusiast

Bmcghan09

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So all I've done is read and read about this. TONS of people had starter issues same issue and ended up being a poorly designed starter. I told Tbarn to go kick rocks (so to speak) when he just said throw a starter in it.  And then the other guy saying put a battery in it.. The dealer said there was not signal going to the starter and I'm doubting them now. I put factory 2825 bulbs in and cleared all the codes. The burnt out bulb or LED light WILL throw a BCM short code! One code came back as history and I cleared it again. Now there's no codes anywhere. So this is my plan, I'm going to go buy a manual horn button the large contact style and run a power to the starter solenoid. Ill zip tie it to the battery bracket. If it does it again I go out and hit my redneck push to start and see if it cranks, If it does then I turn the key and try to see if cranking actually starts it. That will rule out these issues. Also while I'm there I'm going to run the battery tester a few times. I guess if the system even detects a slight change or drop in the voltage it will not send the start signal. 

 

Edit here's the link about the starter issues 

 

Edited by Bmcghan09
Bmcghan09 Enthusiast

Bmcghan09

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Comedic update: I am going to start chasing down all of the grounds off the battery cable and the BCM ground. under the dash. Battery tested good. I was just making a joke about the quality control to my buddy who has friends who work for gm. My joke was they have half blind people doing these grounds... And guess what? His buddy is 50% blind in one eye....  

 

Had a B1325 HVAC control power voltage below threshold

Cleared it and got back today U0020 slow CAN Bus History HVAC. 

BlaineBug Enthusiast

BlaineBug

Posted
Posted (edited)

Strangely enough you speak about grounds.  Unrelated to your issue but if you've followed my thread about the series of interconnected electrical issues that showed up twice in the course of my relatively short ownership, in addition to the advisement of GM TSC to replace the ECM, the technician also found there to be caked undercoating on main battery ground G141.  I'm not exactly sure what he found but I would assume that he meant that the wax coating from the frame was found to be in-between the frame and G141.  There are two main grounds from the battery, G141 and G103.  This information should apply to all trucks and truck platform SUVs I believe.  I'm not exactly sure where this ground is located as I haven't inspected for myself yet.

 

The only code they were finding was for U0100 so that's why the TSC recommended replacement of the ECM.  Under warranty, of course, thank goodness.

Edited by BlaineBug
Bmcghan09 Enthusiast

Bmcghan09

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Yeah I have no warranty for anything electrical. I will be looking at all of the grounds and power when I'm under it hooking up my redneck push button start. 

BlaineBug Enthusiast

BlaineBug

Posted
Posted

So even after fixing the chafed wire in the harness this issue has returned?  Is it possible that the corrosion extended further into the wiring harness?  It is possible to wick up the wire.

This is an extreme case but sometimes transmission fluid has been brought inside the cabins of certain vehicles due to leaking electrical connectors at the transmission.  The oil will literally wick up the entire length of the wiring.

I'm not sure if water has the same "creeping" properties of oil but it's a thought.

BlaineBug Enthusiast

BlaineBug

Posted
Posted
9 minutes ago, Bmcghan09 said:

I haven't found a chaffed wire yet. I will be looking while I'm under it today wiring up my power probe (redneck push button start).

Sorry, I was confusing your issues with Timmer66's issues.

Bmcghan09 Enthusiast

Bmcghan09

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Alright. So I couldn’t do my push to start last night. The screw on the terminal was so rusted it was going to break off the terminal so I didn’t go for it. I took the wheel off the fender flare and the fender liner. The command terminal on the starter solenoid wiggles a bit so I wonder if something internally is broken. I ran a zip tie to hold it tight for now, if it holds. The starter looks like a massive pain in the ass to do. 
What I did find was a rough looking main ground from the batteryZ the rubber coating came down half the terminal I circled how far it came down and then there was a ton of under coating under the terminal itself. I took a pic half way through cleaning the ground up. The red circle is how far the wire coating covered up the terminal. 
 

C0465978-973D-4FF6-B949-55BD2CB19707.jpeg

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