06 Silverado Trouble Code U1300 Help

[Daryl LBZ]

Any kind of insight I can get would be great! So the truck is a 2006 Silverado 2500HD LBZ Duramax. Long story short the truck was working fine until I installed some Sparksmith LED Headlights & Boost Auto Tow Mirrors. Two days after the install I pulled the truck in the garage and noticed the LED strips on the drivers side headlights had quit working. When I installed the tow mirrors they haven't worked from the start.

 

So while I have it in the garage and I notice that now the windows won't roll down, and the key fob no longer works. The truck also will not stay running now. It will start up, run for about 3 seconds, and then shut right back off. So I start looking through wiring all over the truck. Now I just had a transmission replaced as well, but everything worked fine until I added the lights and mirrors. So anyway I can't find anything wrong with the wiring.

 

So I found out that when you have a U1300 code that the various modules can't communicate with each other because something is interfering with the signal. I saw that you can use the splice pack under the dash to help diagnose the issue. The problem there is I can't seem to find it. Any idea if they're always under the dash, or do I need to look elsewhere?

 

When I use my scan tool it can not communicate with the BCM or the Transfer Case Module (Not sure of the technical term for the TC). It can communicate with the ECM & TCM.

 

It's giving me a U1300, U1301, U1016, U1041, U1064, U0073.

 

Can anyone narrow it down with the codes provided, or am I just going to have to go through the trouble shooting steps? I've attached the pages I saved from my scanner as well. 

 

 

 

 

 

[Jsdirt]

You're going to have to go over EVERY single thing you touched during this install.

 

This has all the classic symptoms of a shorted communication wire. Something might have got pinched, insulation nicked, wire broken inside intact insulation (happens a LOT on 21st century GM products), a wire yanked out of a connector, or anything like that. A temporary short may have blown a fuse, too.

 

I recall the underhood fuse box being a problem area on the early D-max engines. My brother's '02 got towed home by me 5 hours 1 way after it crapped out on the highway without warning. I just wiggled some wires beneath the fuse box one day and it was "fixed".

[asilverblazer]

I think the easy thing is to unplug the headlights and mirrors. 

However, I'm inclined to say they are unrelated (unless there was an installation issue that damaged wires). I would suggest checking ground integrity. Clean cables, posts, attachments and make sure the cables are not corroded inside the insulation. Check fuses and inspect for other wiring issues. Make sure all the connectors at the PCM are connected well without corrosion.

Edited December 20, 2024 by txab

[Daryl LBZ]

Thanks guy! I'm going to do some more troubleshooting today, I'll post up my findings. 

[Daryl LBZ]

Ok so I did some more troubleshooting.

 

All my grounds are good, batteries are new, everything under the underhood fuse panel looks fine. I pulled every fuse and none were blown. Replaced every relay with ones from my other junk 2006 truck. Unplugged various modules and none of that has worked.

 

So I ended up doing more research on this and one way to help diagnose it is to get the U Codes (If you can communicate with the PCM) which I obviously can. So as I said above I have a U1300, U1301, U1016, U1041, & U1064. Now apparently the important ones here are:

 

U1016 - No Communication with PCM/ECM - The one that I can NOT communicate with is the ECM

U1041 - No Communication with Electronic Brake Control Module (EBCM)

U1064 - No Communication with BCM

 

Now another way to help diagnose is use a multimeter and probe the pins on Splice Pack 205 and see what the voltage is on each pin. What I've found on this is that a signal above 3.5v is considered high, and a signal belows 3.5v is considered low. With that being said, none of my pins are even putting out anything even close to 3.5v. Here is what I get:

 

A - 0.14v

B - 0.02v

C - 0.00v

D - 0.00v

E - 0.00v

F - 0.61v

G - 0.39

H - Fluctuates between 0.27v - 0.29v

K - Fluctuates between 0.02v - 0.03v

L - 0.58

M - Fluctuates between 0.36 - 0.41v

 

I also read that a low voltage issue usually indicates a wiring problem, open/shorted circuits.

 

 

So that is where i'm currently at, still troubleshooting.

[Jsdirt]

Exactly what I expected to see - a bunch of "U" codes. Something brought the network down.

 

Voltages are tough here - you really need a scope to see the waveform rise and fall to the proper voltage. You already know you have a network issue, so you'll need to go back where you last did work and check EVERY wire in that area.

 

I'm fairly certain at this point something got pinched and shorted to ground, or there's an open somewhere from a harness that got tugged on. Or, something else other than pinching shorted a comm wire (like bad insulation that blew through during the work and shorted after the fact), or a comm wire is broken inside insulation where you can't see it. Have to do the tug test to find those - a PITA. That's a new one for the 21st century, and unfortunately very common on GM products. The wire will look perfect, but the copper is broken inside of it. You have to grab a suspect wire and pull on either side of the suspected break - if it starts stretching like taffy and breaks with a bit more force, you've found it. That can happen either on its own, or from leaning, or pulling on a harness or wire.

 

Since the problem wasn't there prior to the work done, I'd check there before getting too deep troubleshooting everything.

 

One more possibility - the mirrors (EDIT - OR HEADLIGHTS) are extremely chinese and one, or both, are bringing the network down. If you unplug them and everything comes back to life, that's your problem.

Edited January 3, 2025 by Jsdirt

[Daryl LBZ]

Found my issue!

 

I was looking around under the drivers side dash and I tugged on a small bundle of taped up wires and they didn't move. As soon as I saw that I knew. When I put the nut back on under the dash where I put the ground for the mirrors I somehow managed to pinch the purple wire from the OBD2 port, so it was grounding out. As soon as I took the nut off and got the wire out everything started working again. I fixed the wire and off she went!

 

Sucks that it was my fault, but at least it was an easy fix.

[Jsdirt]

Awesome man! Glad you found it! They can really be a PITA to hunt down sometimes. 

[asilverblazer]

On 12/20/2024 at 2:55 PM, asilverblazer said:

...unless there was an installation issue that damaged wires...