Need some help guys!

I own a 92 coup and today when I got in the car the digital cluster was blank...no speedo...no fuel display...nothing but the orange background. I sat in the seat and was about to check the fuse when suddenly everything just popped back on and seemed to be working fine. I took off in the car and 15 mins or so later noticed that where the coolant temp display number was it was alternating from "180" degrees to "sys"...it kept going back and forth from whatever the coolant temp was to "sys". Everthing else was working fine and I figured when I got home I'd look in the owner's manual and find what the problem was but I turned onto a particuliarly bumpy road and everytime I hit a bump the entire cluster would freak out! I was getting partial numbers and it was switching from coolant temp to volts to oil temp all by itself. The fuel guage appearing and disappearing, it was switching to the odometer as well then to the fuel calculating display. It was a mess! Then as I hit a smooth patch of road everything would work fine except the coolant was still flashing "sys". All the analog guages were working fine and no warning lights ever lit up on the dic. I looked in the manual and there was was nothing about the "sys" that was popping up...so I need you guys help. Anyone ever have this happen to them? Everything else works fine on the car and it ran great! Please help...I DO NOT want to take my Vette to the local chevy dealership as my car is heavily modded...but I've never done anything to the instruments!

Any help would be appreciated.

Bill

 

Any help at all?

 

I also have a 92 coupe with the identical problem. It occurred right after I pulled the ECM . I belive its a wire or connector in the harness coming out of the ECM . I have changed the ECM to a known good one & the transient problem re-occurs . I stop when it occurs ,gather the wires in the harness together & it ceases for days. So I figure the problem is right there, I'm going to unplug the harness,spray it with contact cleaner & check & clean the grounds.
Warren.

 

The "SYS" means "SYSTEM."

The SYS display is the way the CCM (notice this is CCM not the ECM) notifies you of a problem or trouble code being set.
You need to retrieve the trouble-code from the CCM.

The CCM also drives the digital display.
I'm guessing you have a problem in the CCM.

However, make sure you have a fully charged battery and the ground connections are tight.


Tom Piper

 

Thanks for the replys guys.

So a permenent solution to my problem is to get the error code from the CCM and proceed from there? So I guess I'll have to take the car to the dealership to get the code.

I'm not a mechanic, so 2 questions.

What is a ECM? Also what is a CCM?

Thanks, Bill

 

The ECM is the computer that controls the engine and it's accessories.

The CCM is also known as the Body Control Module, the master computer. It controls the communications on the serial-bus.

There is a procedure for getting trouble-codes by displaying it on the digital display with a paper clip and the buttons on the dash -- but, since you can't trust the digital display to work, that may be a problem.


Tom Piper

 

I have a thought..first let me ask you if you have had ANY transmission work done on the car recently? Check the main cluster ground on the transmission bell housing on top. Cant see if with the trans in..very common for the ground to not be replaced or damaged after trans work. Also there is a ground near the drivers left firewall where the harness runs into the firewall.

 

I have the same problem on my 92 LT1. I have cleaned ALL 9 grounds on the chassis and the one on the engine bellhousing bolt and no difference. I have also pulled the CCM codes and there are no codes only C12 so this is no help with this problem.
If you get the solution please post it as this seems to be a recurring problem on 92 cars.
Jerris

 

Hi Guys,
If you go yo yhe top of this forum page and click on "other" scroll down to "tech Tips" and click on C4 there is an article on how to correct this problem with good pictures and everything.(as well as alot of other useful articles on the 1992). To get it to print I had to copy it to microsoft word and print from there as the format on the forum does not fit on a page and you loose some of it.
Unfortunately it does not come up when you do a search on digital dash problems, I found it accidently yesterday (maybe it was fate) and last night took apart my dash and fixed it.
Just put dash back in and everything appears to be working fine.
Thanks Corvette forum for the timely info.
Jerris

 

Thanks for the replies guys. I guess this is a common problem in 92s it seems.

As for the tranny...I have a Rossler tranny in the car w/a Yank 2800 TC but this was installed at Lingenfelter 2 years ago when they did my 383 and I've had no issues with it at all.

I'll check out what you found jerris.

Thanks guys.

Hope you other guys get your problems worked out as well.

Bill