Odd electrical problems

[Jadalexm]

Hey everyone. New member here and I’ve got an interesting issue. Just bought my 01 Yukon Denali xl and I got it pretty cheap because the previous owner said lightning struck some wires near the truck when it was in Florida and now it’s got a draw on the battery and the gauges go crazy. He said he had the cluster sent out and nothing changed. He installed a lever on the ground of the battery so you can easily disconnect it so it doesn’t drain, and I don’t think that helps much. There’s no way it makes that great of a ground connection. Anyone with experience have an idea on where I can start investigating? I have a huge list of stuff I want to do to this but I have to get this taken care of first so I can at least get it inspected. Haha.

This is a video of the cluster freaking out. Which it does non stop.

https://imgur.com/a/14XGFPH

 

[Tonyv__]

Simple test I learned was to just use a regular 12v bulb and put 2 wire leads on it + and - Make sure the key is out of the ignition and just start pulling fuses 1 by 1 and stick the leads from the bulb in place of the fuse. If the bulb lights up then that circuit could lead you to your parasitic draw.

Obviously a multimeter would work better but last time I had this issue. I didn’t have any tools and a bulb was what I used.

 

[swathdiver]

Hey everyone. New member here and I’ve got an interesting issue. Just bought my 01 Yukon Denali xl and I got it pretty cheap because the previous owner said lightning struck some wires near the truck when it was in Florida and now it’s got a draw on the battery and the gauges go crazy. He said he had the cluster sent out and nothing changed. He installed a lever on the ground of the battery so you can easily disconnect it so it doesn’t drain, and I don’t think that helps much. There’s no way it makes that great of a ground connection. Anyone with experience have an idea on where I can start investigating? I have a huge list of stuff I want to do to this but I have to get this taken care of first so I can at least get it inspected. Haha.

This is a video of the cluster freaking out. Which it does non stop.

https://imgur.com/a/14XGFPH

This guy knows his stuff:

https://www.youtube.com/channel/UCzJWy4r_V89YYt4GBxNaJfQ

 

[rockola1971]

Pull the IC and clean the rear of the circuit board off. I suspect you have silver migration going on there. This will cause the BCM to never goto sleep and IC will go nuts depending on what parts of the circuit are bridged.

 

[Jadalexm]

So I have an update on this issue. Turns out I don’t have a signal at my obd port either. There’s power there, but I can’t connect. I replaced the ecu thinking it was causing that issue and the dash going crazy, but everything’s the same. I’m also trying to fix my air level suspension too cause that won’t turn on. I’m curious if the abs light has to do with that, but again, can’t read codes so I have no idea. Any help is appreciated.

 

[TollKeeper]

Stupid question, have you tried a different OBD reader? A tech2 is going to read your ALC, but any generic one should be able to read the PCM.

 

[Rocket Man]

By ecu do you mean body control module or powertrain control module?

 

[PNWYukon]

Check for rats inside/under the fuse box.

Get a wiring diagram and trace the wires.

If your underbelly is crusty, trace all the grounds and reseat them.

 

[Jadalexm]

By ecu do you mean body control module or powertrain control module?

The pcm. I read somewhere that it could be the bcm causing all the lights on the dash and the low voltage to the obd port.

 

[Jadalexm]

Stupid question, have you tried a different OBD reader? A tech2 is going to read your ALC, but any generic one should be able to read the PCM.

I tried my little matco hand held reader. Then I tried the snap on one from work. The snap on one actually gave me a message that said vehicle voltage to scanner too low.

 

[TollKeeper]

That could be a fuse, or an alternator not putting out enough volts OR amps.

 

[Jadalexm]

An update for anyone interested. I broke down and paid the money for a month of alldata. I used all the wiring diagrams to find the data line splice pack. Unplugged the splice pack with my scan tool hooked up and saw all the modules do offline. I jumped the purple obd wire to each communication wire 1 at a time and found that the SCM or suspension control module was the one that made everything go haywire when I brought it back online. Got the plug diagram for that module and checked the communication wire right at the plug and found that everything before the module is fine. And with the module unplugged all the issues went away, except the air ride didn’t work. So until I feel like throwing 1000 dollars at a new scm, I pinned the communication wire out of the plug so I still have air ride and don’t have the electrical issues. Only downside is that I can’t communicate with the chassis system so I hope I don’t end up with an ABS code down the line that I have to read. Haha. But yea, dealer wants 700 for a new module and 350 to program. So that’s a pass for me. I’m attaching the wiring diagrams I used in case anyone else needs them in the future.

 

[Rocket Man]

An update for anyone interested. I broke down and paid the money for a month of alldata. I used all the wiring diagrams to find the data line splice pack. Unplugged the splice pack with my scan tool hooked up and saw all the modules do offline. I jumped the purple obd wire to each communication wire 1 at a time and found that the SCM or suspension control module was the one that made everything go haywire when I brought it back online. Got the plug diagram for that module and checked the communication wire right at the plug and found that everything before the module is fine. And with the module unplugged all the issues went away, except the air ride didn’t work. So until I feel like throwing 1000 dollars at a new scm, I pinned the communication wire out of the plug so I still have air ride and don’t have the electrical issues. Only downside is that I can’t communicate with the chassis system so I hope I don’t end up with an ABS code down the line that I have to read. Haha. But yea, dealer wants 700 for a new module and 350 to program. So that’s a pass for me. I’m attaching the wiring diagrams I used in case anyone else needs them in the future.

You can find used SCM’s on EBay for cheap. They don’t need to be programmed. I’ve swapped the one out on my 02.

 

[Jadalexm]

You can find used SCM’s on EBay for cheap. They don’t need to be programmed. I’ve swapped the one out on my 02.

Really? I bought a used one on eBay for 80 bucks and I plugged it in and the truck started once then the security light started flashing and it wouldn’t start again. Put the old computer back in and it went back to running fine. Figured it was because of the programming.

 

[Rocket Man]

Really? I bought a used one on eBay for 80 bucks and I plugged it in and the truck started once then the security light started flashing and it wouldn’t start again. Put the old computer back in and it went back to running fine. Figured it was because of the programming.

With an SCM? The module that’s behind the right rear cargo area panel? I can see that with the BCM or ECM but not the SCM. I’ve had mine unplugged before, no issues other than compressor didn’t come on.