rwsduc

Leaving work today, I saw something new and a bit troubling on my 92. I noticed the water temp digits went to "888", then flashed "SYS" three times, then went back to the water temp. After a few seconds, the cycle would repeat. While at a stop light, I referred to the owner's manual and read that this indicates a problem with the CCM and the indication would be repeated every 15 seconds. I had to make a stop for a few minutes and when I started her back up, everything appeared normal for the rest of the drive home.

Once I got home, I pulled the codes from the CCM (jumper pins A & G) and received the following history codes: (as defined by my Helm manual)

27 - LCD blanking control circuit open or shorted to ground
32 - LCD data circuit open or shorted to ground
34 - Data clock circuit open or shorted to ground
36 - Data strobe circuit open or shorted to ground
37 - M clock circuit shorted to B+ or CCM internal open

Neither the ECM or ABS/ASR modules were displaying any faults.


Before I start tearing into the dash to clean and reseat the CCM connection, I wanted to get a sanity check from the rest of you. Have any of you experienced this particular situation before? I find it odd that it occurred out of the blue, then went away 20 minutes later when the car is started up again. Thanks in advance for any insight!

rwsduc

I take it not many have had to deal with CCM issues like these?

Hotred94

Could be your battery going south. Mine ran that way for a year. No real problem, just flashing all the time.

TomHamill

Mine did that once just before I put a new battery in.....

kabnvtt

My 92 ZR-1 did that yesterday and I know the battery is weak. I am positve that the flashing SYS is due to the weak battery. Not sure about 888, I have not seen that yet.

bogus

sounds like the temp sensor may have taken a crap. It's the one on the water pump.

rwsduc

Hi all, thanks for your replies. I replaced the battery a couple weeks ago (unknown age...call it a pre-emptive maintenance strike) and I never got this fault until after I replaced the old one. Yesterday the whole dash blanked out on me on the drive home and finally came back on when I hit the bump coming into my driveway. Today the dash displayed garbage (seemingly) every other time I hit a rough patch of road, then would appear normal again a few seconds later. I'm not looking forward to messing with the dash or CCM, but it seems inevitable.

Also, I didn't specify in my first post that the flashing "SYS" indication would occur regardless of whether I had oil temp, coolant temp, volts or fuel info displayed. The digital temp is reading normal for any given driving condition, so long as the dash isn't flipping out on me. So far, the "888" reading has only occurred the one time.

BubbleHead

I'm seeing the exact same problem AFTER picking my car up from the dealership. They replaced my Opti and computer saying they were the cause of my car dying out on me. Now, I get this error.

Also, I did notice my "security" light comes on at the same time the "sys" is displayed in the LCD. My battery is fine and reads 14.1 volts.

rubydog

Please help. Have similar problem; "sys" in odometer area and security flashing...but I get C41, H41, H54 and H72 when I run CCM test. Also get "err" on test #4. ECM diagnostic gives 12...so its OK I guess. But my 93 Ruby red (with only 28K miles) won't start! It turns over then immediately dies. The flasing "sys" has gone from intermittent to immediately coming on when I turn on key. (There is pressure on fuel rail ruling out fuel pump, etc.) I have service manual and based on what I read I am suspecting serial link down. Furthermore, I suspect CCM not sending FEDS fuel enable to injectors so ECM shuts them down immediately after a successful crank. (when ECM and CCM find out they can't communicate). In early stages of problem, I got "Check ASR" on dash but I could start the car. Now its dead. Am trying to avoid tow bill. Someone mentioned ECM loading down serial link to CCM and its probably ECM vice CCM. Any advice would be greatly appreciated.

93_vette

Ok. Here's an explination of the sys indicator on the lcd panel as stated by the gm service manual.

A DTC (Diagnostic Trouble Code)-setting malfunction in any of the CCM-monitored systems is indicated by "SYS" (system error) flashing in the instrument panel. If the malfunction doesn't recur within 100 ignition cycles the CCM (Central Control Module) will automatically clear the code.

Since the Service Engine Soon light monitors engine performance, the CCM needs a way to communicate that something is wrong. The flashing SYS is how it does that.

To pull the codes for the CCM one has to ground the G pin in the Data link connector (the OBD I connector) located under the dash. You will really need the service manual in your possession to diagnose the problem though.

Marlon