Instrument cluster out

Johnrkennedy · May 19, 2015

Hello,

Recently replacing the fuel pump and fuel lines on my 2500hd, 8.1 Vortec, resulted in the cluster going dark. When the OBD is plugged in, everything works. Unplug, and the cluster goes dark. All fuses are good. All wires are good. Because the battery was unplugged for a week, does anyone know if having a dealer re program the truck will bring back the cluster?

Thanks

diggerdan11 · May 19, 2015

Thats strange. I have never seen a cluster go completely dark. Ive seen bulbs go out, stepper motors fail, and the display go out, but never the whole thing.

You can call your dealer and see what they have to say, but I have a feeling they will charge you a ridiculous amount.

You could always give Steve Letcher (The GM Gauge Guy) a call or email. He is the cluster expert, and may know what the problem is. If you have to have him fix it, he does amazing work and you wont regret it.

http://www.gmgaugeguy.com/

ifixedit · May 19, 2015

I used these guys last fall and were great to work with, I'm sure they can tell you what the issue is.

http://ddinstruments.com/

Johnrkennedy · May 21, 2015

thanks for you quick responses. As you can tell from the description, this is very strange. However, I did find two other identical threads from people with the same problem, but there was no solution. I actually have the GM shop manual and the illustrations show the wiring harness for the cluster goes back through the firewall to the under hood junction block. There, there are two connectors to power the entire IP, not just the cluster. My next attack will be to access those connectors and test the grounds. I suspect that this may be a ground issue because by plugging in there OBD, you bypass the cluster ground and use the OBD connection. Before I cut things up, I will need to verify. Common sense tells me that something came loose when I was working on the lines, but everything I check is good. Somewhere, I am missing something, or did this happen by coincidence? Chances are no and something simple is the answer.

ifixedit · May 22, 2015

So if you unplug the OBD the cluster goes dark? How about when the truck is running with the OBD disconnected, still the same? Do the gauges at least work or is the whole thing dead?

Johnrkennedy · May 22, 2015

So if you unplug the OBD the cluster goes dark? How about when the truck is running with the OBD disconnected, still the same? Do the gauges at least work or is the whole thing dead?

Hello,

Entire Cluster goes dark when you unplug the OBD. Plug the OBD in and everything works. Latest info is a pin out reading and Pin 8 is not grounded, either with or without the ignition on. Plug in the OBD and pin 8 is grounded.

I am ready to pigtail the black wire with white stripe from Pin8 and ground it.

Thanks,

John