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Discussion Starter · #1 · (Edited)
Alright, so I bought this truck for fairly cheap. Its an 03 with an LB7, needs injectors(go figure), and other misc stuff. But this is what I am trying to figure out right now:

With the key in the RUN position with the engine OFF I have no gauges and no warning lights coming on. The radio, auto headlights(and dash backlights), and glow plug lights come on, but nothing else. But when you start it, the gauges go right to doing what they are supposed to. My cluster is super dim and after replacing some fuses, the odometer screen had weird looking lines on it, like hieroglyphics almost? I have a picture.. will see if I can attach it.

So there is that then...

Plugging my Snap-on Triton D8 into the DLC it comes on, knows its plugged in(so has 12v and ground) but can't get a vin and when manually entered it can't communicate with any module. I verified there is 12v on the orange wire, ground on the pins 4 and 5(chassis and signal ground) all is good there. I unwrap the loom and follow the purple wire up to the Splice Pack (SP205 on wiring diagrams) where it is shown that all the modules data wires come together and go into the DLC, all this appears to be fine.

Now..

Plugging my Mac MDT10 with J2534 interface into the DLC it sees all the modules but when scanning for DTCs it won't read any modules. Pulling up live data, it appears to be reading normal, but couldn't start the truck at the time to verify.

I am going to mess with it more tomorrow and report back with more info. If anyone has any sort of guidance with this stuff, I will be glad to listen. Thanks!
Speedometer Trip computer Odometer Gauge Tachometer
 

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Discussion Starter · #2 ·
Alright. Got scanner communicating. Ended up being a crappy aftermarket radio module messing with the serial bus. All is good there.. now the cluster. Cluster still won't do anything key on engine off.
 

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2007 GMC Sierra LBZ
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Check the ground strap going from driver side engine to the firewall. I know that can mess with the cluster if not connected.
 

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When my cluster was doing that alien language business we found a microchip that controls that to have a blister on it. It looked like it had been hot and a little plastic bubble had raised on it. Sometimes it would work and other times it wouldn't. There is a local rebuild shop here that removed the solder and lifted it off, replaced it with another from a parts cluster and got it back to 100%. They were experimenting with mine to see if it would even work though and recommended total replacement in most cases.

Kincers fixed mine: https://www.kincercorp.com
 
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