99 Z28 gauges unresponsive, help!!

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Feb 18, 2022 | 08:45 AM

RedShoto

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Teching In

Joined: Feb 2022

Posts: 2

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From: Texas

99 Z28 gauges unresponsive, help!!

Hey everyone, I recently picked up a 99 Z28 for a good price knowing it had a gauge cluster that didn't work. Central locking works, windows work, radio works, I believe the AC doesn't work (original owner jumped the ac clutch signal to the fan control signal, I'm looking to fix this) and the OBDii/12v socket fuse is good. Scanners fail to connect to the car, but they do power the scanner on. The car came with a trans am cluster as a spare and I swapped them to see if anything would change but both clusters show the same faults and lights. The only operational gauge is the Volt meter. I had a tech look at it and try to connect directly to each module in the car and he was able to connect to all but the PCM. We swapped a reman PCM into the car and still had the same issue. Our guess is the can line is broken somewhere along the harness but haven't been able to check for continuity yet. Has anyone had any issues like this or ideas what to check next?
any help would be amazing!!

Thank you!

Apr 14, 2022 | 02:33 PM

cobra30689

Staging Lane

Joined: Feb 2016

Posts: 70

Likes: 6

There is a splice pack under the dash, directly to the right of the OBD connector. Might have to dig around for it a little.....has 5 wires going into it with a grey cap. It ties all the comm circuits together to pin 2 on the OBD port, and the whole point of it is to facilitate comm circuit diagnosis. You can unplug the cap, make a jumper to go from the module you want to pin 2 of the DLC for diagnosis. Helps when one module is pulling the whole bus down. Line to the PCM is DK GRN. I attached the Class 2 bus diagram. Good luck.

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