1992 Eldorado/Seville instrument cluster

[Astrak]

So I have searched on the internet and have found that the IPC for 92 Eldo's and Sevilles have a problem with intermittent loss of communication with the PCM causing the AC to quit and the fuel economy to show dashes. Does anyone know a fix for this without sending the IPC to a repair shop? I called a local place here in Tucson but they don't seem to know a darn thing(typical for this part of AZ, I wish I was back in Nebraska where people had brains)anyways I was wondering if there is a simple fix for this.

[Logan]

It is not just the '92. Include '92-95 Seville. And '94-95 Deville. "--" display etc.

Failure mode is 'loss of data' issues on circuit 800.

Circuit 800 is the UART data line. Today that circuit is known as the Class 2 data network.

So any of the computers on circuit 800 can cause your problem. Anything that screws up the data transfer. These include:

PCM/ ECM

ABS

IPC

DERM

ACP

That being said, my '93 had this issue. Problem was extremely intermitant. Maybe 20 minutes every 1K miles.

That being said part 2: After several months, I pinpointed the IPC as being the issue. I could press and hold the IPC connection is such a way as to induce failure after 30 seconds or so.

I personally looked at my cluster/IPC...and did not notice any apparent fault. Part of this was the clusters are sold on a 'rebuildable' core exchange basis. I did not want the destroy the core.

Off to the local Delco cluster/radio shop. Walk cluster in...explain problem...wait...

Tech comes out....'cluster tests ok' . I say 'no, bring cluster and follow me....'

I then plug cluster in car. Show tech the DVOM on pin M (circuit 800) on ALDL showing flucuating voltage....then push the connector as descibed above for 30 seconds.....failure... DVOM voltage locks....15-20 seconds latter cluster is displaying '--' and codes.

Tech: "Oh crap, we dont test for that"

Anyway, new IPC fixed mine.

That being said part 3: Turns out, the huge Delco cluster diagnostic machines do not really test circuit 800 failures in the IPC. To them...."--" display is normal during diagnostics procedures. Go fix that Delco!!

I have heard of cars...needing 3-4 'rebuilt' clusters to fix IPC '--' circuit 800 problems.

Many Delco radio shops no longer repair clusters. Our local one included. I think they all got burned on these.

'--'

[Astrak]

So I should just mess around with where the two connectors plug into the IPC and see if I can get them to cause the failure mode. The failure in mine happens every day it will quit working for no reason and then come back on for no reason.

[Logan]

So I should just mess around with where the two connectors plug into the IPC and see if I can get them to cause the failure mode. The failure in mine happens every day it will quit working for no reason and then come back on for no reason.

If you are lucky. It is a very long failure mode....so it takes 30-60 seconds to induce the failure...while pressing on the plug a particular way.

The faster way is to use a DVOM on pin M to ground. Watch the voltage fluxuate. The voltage will lock once in failure mode. 30-60 seconds latter the cluster will start displaying '--' and setting codes.

In my case I was lucky....that I could induce the failure every time.

Your problem could be one of the computers mentioned. If any of them can pull the 800 signal down....you get '--'. It's a tough problem to pin point.....as are most intermitants....