marunos

I need your experience and help, guys. I run my car yesterday with half of instrument cluster not functioning. Everything before that looked normal, I have never had this issue. It just happened like that .. after almost 4 days of not running the car, I came to find out this messed up issue.

So I run the engine and Tach, fuel, coolant temp gauges are no functioning (speedometer, battery, oil pressure are OK). Also, many lights are on: Service Vehicle, Air bag, Check gauges, ABS INOP.

I tried to scan for any error codes , but funny, the scanner couldn’t connect to the vehicle - although I have done scanning many times in the past.
I run the car on road and everything looks normal and drives great. Radio, windows, lights, remote locking/unlocking …all are functioning properly.

I don’t know from where should I start? What could be the possible causes for this specific gauges/lights issue.

I appreciate any advice from you.
Thanks.

VTC_WS6

iTrader: (9)

If you can't connect to the car, check fuses in the drivers side fuse block on the side of the dash. I don't recall which fuse it is but one of them controls the OBD-II data port circuit.

marunos

thought the OBD-II issue is somehow related to the gauges warning lights.. will do so .. thanks for the hint

VTC_WS6

iTrader: (9)

Could very well be, but that at least eliminates one possibility. I spent like 30 minutes trying to diagnose my non-connectivity issue with EFI Live only to realize that I'd blown the OBD port fuse

joecar

The cigar lighter fuse.

marunos

I am out of town now, guys, once back I will check the fuses you mentioned! Thank you .. I will post what i find out.

marunos

Really! what is the relation between the gauges and the cig lighter fuse??? can you give more tips please? I have heard once that you need to check if your cig lighter has something stuck there which can cause fuse problems, but I never thought that my issue can be somehow related!

jcvett56

same circuit

marunos

Guys, I checked all the fuses ( on driver side, and underwood) all fuses are ok.

marunos

Ok I found out also that the car struggles when i try to start… I thought it is the battery since it has been now more than 4 years.. but when i put a new battery it still struggles before it starts normally. I checked also all the grounds around the engine and it seems they are OK

MontecarloDrag

iTrader: (3)

You have a short or a broken wire in the Class-II data bus. It drives the cluster and also the OBD2 port.
Find some schematics and check the harness

marunos

thanks man… where is the harness of Class-II data bus located in F-body? any idea.. is it visible if you check out under the hood?

MontecarloDrag

iTrader: (3)

Most of it is under the instrument panel. Find a black square box with several wires attached to it. It is the splice pack and sometimes it can loosen or get corroded.

https://ls1tech.com/forums/general-m...-problems.html

I attached the diagram of the serial bus in PDF.

marunos

Great.. thanks.. looks like i will need to remove the knee cover under that.

marunos

marunos

This is what I found ... Is it related to my problem ?

marunos

marunos

Yes . Indeed it was the issue, I cleaned that.. And replaced the affected pins.. Now everything works normally.. It seems that interface from the Pcm has lost the sealing..

marunos

OK so after fixing that, I told you that the gauges work as they should do.. how every the car drives like $h!!!t ! when ever I slow down it , the rpm falls down and it goes off.. I know it might be re-learning (correct me if wrong) but how would that go? and for how long..? any experience on that?