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No starting issues w errors

robert24b

By robert24b
in Troubleshooting & Recalls

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robert24b Enthusiast

robert24b

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25 minutes ago, richard wysong said:

with the warnings and the scanner not connecting it's pointing toward a BCM or buss problem possibly because of a bad ground. There have been numerous posts of similar problems and I don't believe anyone has posted the cause or cure,PLEASE when you figure it out post the fix! Reading past posts I believe there is a ground splice pack up high in the dash on the left(?) side that has the grounds for the buss network. Hopefully someone more knowledgable than me will chime in here

Thanks Richard! You've given me an additional area to check!

 

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robert24b
robert24b

This explains it better than I can   https://youtu.be/227dndw46JY

richard wysong
richard wysong

erikwink6 has a similar post going titled "no start after dash repair" that has a detailed explanation of the starter system

ksiesel
ksiesel

I had something similar with my truck while it was under warranty.  It was the datalink wires shorting together up near the rear tire.    The key switch is wired to the BCM and it has to tel

robert24b Enthusiast

robert24b

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UPDATE:

 I removed the starter relay and jumped it out, engine turned over. Also swapped out the relay with another.

Still won't start though via the ignition. 

I guess that rules out the battery and starter?

richard wysong Senior Enthusiast

richard wysong

Posted
Posted

look at the video posted by BlaineBug under popular forum topics. check the body and frame for ground voltage drop

  • 5 weeks later...
richard wysong Senior Enthusiast

richard wysong

Posted
Posted

So without seeing a wiring diagram I would guess the wire from the relay to the starter must be broken, I would check it at the starter as that would be the most common trouble area. Are you sure you jumped the correct terminals at the relay and there was 12v at the relay?

ksiesel Enthusiast

ksiesel

Posted
Posted

I had something similar with my truck while it was under warranty.  It was the datalink wires shorting together up near the rear tire. 

 

The key switch is wired to the BCM and it has to tell the ECM to engage the starter relay via datalink.  If those two aren’t talking, it won’t crank.  I also had all the dash messages you have along with an outside temp reading of -40 (it was around 60 F then). 

 

This theory also aligns with your observation that a scan tool will not connect.  

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robert24b Enthusiast

robert24b

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4 hours ago, ksiesel said:

I had something similar with my truck while it was under warranty.  It was the datalink wires shorting together up near the rear tire. 

 

The key switch is wired to the BCM and it has to tell the ECM to engage the starter relay via datalink.  If those two aren’t talking, it won’t crank.  I also had all the dash messages you have along with an outside temp reading of -40 (it was around 60 F then). 

 

This theory also aligns with your observation that a scan tool will not connect.  

Thanks for that info! I need to scour that area again but It was tough due to the harness being sandwiched between the frame rail and bed. Gonna take the wheel off this time to look.

Which side were you having trouble on? Driver rear or passenger?

I finally end up taking the truck to the dealership and it's been there since 11/1 and they're just telling me "we're working on it". Sounds like I need to prepare for some expensive news.

 

 

Thank you!

 

ksiesel Enthusiast

ksiesel

Posted
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My datalink short was right at the terminating resistor on the drivers side.  You should be able to check this datalink circuit by measuring resistance from Can H to Can L with the key off and all harnesses/modules plugged in.  There should be a 120 ohm terminator at each end and they are in parallel.  A good reading will be around 60 Ohms.  I believe you can check it at the DLC under the dash, but I don’t recall what pins.

robert24b Enthusiast

robert24b

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OK, just spoke with the dealer and after 29 days, they have diagnosed my truck with a shorted HMI module. 

I gave them the ok to repair at $1500. Ugh. 

Once I got home, I had the opportunity to look up the module and found them for around $300. Zeesh......that's why they're called the "stealership".

Oh, after the dealer told me the price, he still tried to upsell me on a cabin filter and wipers!

Hopefully she will be fixed soon!

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robert24b Enthusiast

robert24b

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I was confused as to how a module that controls the radio and navigation prevents the truck from starting but, the video explains how there's a "network", a sort of LAN that ties into the ignition circuitry. 

I wish I knew about this video before authorizing the dealer to complete the work but, quite honestly, when it comes to these computerized vehicles, I don't have any way to check for dead modules.

MikeBMW Senior Enthusiast

MikeBMW

Posted
Posted (edited)
28 minutes ago, robert24b said:

This explains it better than I can

 

https://youtu.be/227dndw46JY

@pgamboais always a font of electrical information when it comes to these trucks! I have bought a few harnesses from him and he's very responsive and helpful.
harnessdr.com

Edited by MikeBMW
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