1996 K2500 Gauge cluster electronics issue

[thelastoutlaw78]

So this evening I removed the dash to replace components in the HVAC assembly behind the dash. After reinstalling the HVAC assembly, dash, and steering column I noticed that upon turning the ignition switch to the run position my high beam indicator lamp was on dimly and the left turn indicator lamp was on. Upon starting the truck up the tachometer no longer registers. However when the brake pedal is depressed it starts to register. I checked the ground underneath the dash on the tie bar and it tested out okay. I ran a ground from the battery to the ground on the tie bar and nothing changed.

So my questions are:
1. Is there a second ground that I missed upon reinstallation of the dash and components? The only one I recall removing is the one on the driver side below the fuse panel.
2. Is it a grounding issue at all?

This one has me stumped. I am very knowledgeable about the 1988-1994 OBD 1 systems but I'm fairly green with the 1996-1999 OBD 2 systems in these trucks. Any info is greatly appreciated and hopefully I don't have to remove the dash assembly again.

 

[kolgeirr]

I haven't had this issue personally, so just a hunch here from when I took the dash out of my Suburban. Those are all circuits that go through the firewall. Take a look at the bolt-together firewall connector and see if it's fully seated. That thing's pretty awful to put back together given the wonky angles you gotta work at and can get crooked enough where it feels in, and the screw is tight, but it's not actually fully seated.

 

[thelastoutlaw78]

I haven't had this issue personally, so just a hunch here from when I took the dash out of my Suburban. Those are all circuits that go through the firewall. Take a look at the bolt-together firewall connector and see if it's fully seated. That thing's pretty awful to put back together given the wonky angles you gotta work at and can get crooked enough where it feels in, and the screw is tight, but it's not actually fully seated.

So I never disconnected that plug in the firewall. I removed the wiring and components from the dash itself.

With that being said, I've removed the dash shell itself and reinstalled the components to where the plug in at and searched the wiring for anything not plugged in or not grounded. The only ground I've found and which I knew about was the one below the instrument panel on the tie bar. I've traced the wiring out and found no other ground nor broken wiring. And come to find out the radio no longer transmits to the speakers. All of this worked previously before removing the dash to replace the components in the HVAC plenum.

 

[kolgeirr]

So I never disconnected that plug in the firewall. I removed the wiring and components from the dash itself.

With that being said, I've removed the dash shell itself and reinstalled the components to where the plug in at and searched the wiring for anything not plugged in or not grounded. The only ground I've found and which I knew about was the one below the instrument panel on the tie bar. I've traced the wiring out and found no other ground nor broken wiring. And come to find out the radio no longer transmits to the speakers. All of this worked previously before removing the dash to replace the components in the HVAC plenum.

Well I'm out of specific ideas then, but hopefully this information from a thread on instrument panel issues can help. The second picture lists all the ground locations; looks like G200, 201 and 202 are in the dash. Two on the left, one near the HVAC on the right. The grounds for the systems that leave the cabin are likely all outside of the cabin, looks like a few ground at the thermostat and RH cylinder head. Beyond that I'll need to leave it to someone else unfortunately.

 

[thelastoutlaw78]

Well I'm out of specific ideas then, but hopefully this information from a thread on instrument panel issues can help. The second picture lists all the ground locations; looks like G200, 201 and 202 are in the dash. Two on the left, one near the HVAC on the right. The grounds for the systems that leave the cabin are likely all outside of the cabin, looks like a few ground at the thermostat and RH cylinder head. Beyond that I'll need to leave it to someone else unfortunately.

I appreciate any info I can get. Will look tomorrow and try to locate them. Thank you.

 

[Scooterwrench]

Does your I/P have the plastic film integrated circuit on the back? Sometimes those can get pushed out of position or the connector not fully seated.