2003-04 GM Truck issue

[Relentless]

I have this cluster that is not receiving the serial data, the trans temp, bolts, oil pressure, engine temp and gas gauge do not work, as well as the gear selector underline on the vfd. The tach and speedometer do work. The stepper motors will reset when power is supplied but they get no reading to display. I've had this problem before and thoroughly cleaned the black corrosion off of the back of the pcb and it fixed it but that did not help this situation, any ideas?

[Relentless]

Anybody had this issue? Just junk it and rob parts or?

[clusters]

Corroded via or a bad processor. If you flex the board and it comes back to life it is a corroded via. (little holes that join the front of the board to the back)

[afitijuana]

did you check Gmland

[Relentless]

Corroded via or a bad processor. If you flex the board and it comes back to life it is a corroded via. (little holes that join the front of the board to the back)
My thought with how much corrosion there was is that it could've shorted something out or there's corrosion internally in the pcb

did you check GmlandI am not sure what you mean by this

[clusters]

If there was a lot of corrrosion then I would suspect it corroded through a via. Try following the traces from Pin A6 to the processor and check all the vias for continuity from the front to the back, look for the ones that are blackest right in the hole. If you find which one it is please post a picture of the location.

The problem is you need a scantool capable of communicating with the cluster or doing a gauge sweep test to test them on the bench. Unless you have the truck there.

I have a few dead boards, so at some point I'm going to strip the coating off the front so I can see all the circuits clearly to map them out. Just haven't got around to it.

[clusters]

OK, did a little playing around today, that paint coating is impossible. lol Nothing I had would strip it not even paint stripper so I had to sand a bunch off a junk board.

The problem could be in the circuit that controls the 56585 chip.

[Relentless]

I have been slammed but I'll try to break this board back out tomorrow and test these things. I ordered an MDI last week so I'll be able to do more things soon. I do have one of these trucks though, so I can always test things that way.

[clusters]

I do have one of these trucks though, so I can always test things that way.

That makes it easier. lol