No starting issues w errors

[robert24b]

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!

 

[robert24b]

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]

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

[richard wysong]

Any progress?

[graves4wheeler]

did you fix it , i tried jumper wire at starter relay , no happened , but i can cross starter and solenoid it will start , could use some help 

[richard wysong]

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]

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.  

[robert24b]

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!

 

[richard wysong]

Keep us posted on the outcome please

[ksiesel]

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]

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!

[richard wysong]

What does the HMI module control?

[robert24b]

This explains it better than I can

 

https://youtu.be/227dndw46JY

[robert24b]

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]

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 November 30, 2022 by MikeBMW