Help! SYS and Service Engine Soon light problem

[wolfnaz]

I have a 1990 L98 Corvette. When i start the car; i get a "Service Engine Soon" and a "sys" flashing together. I'm not able to get a trouble code when a scanner is connected. I just replaced the ECM due to the same problem before i replaced the old ECM. Any help would greatly be appreciated???

 

[Hib Halverson]

Replacing the ECM was a waste of money.

Have you reviewed the CCM diagnostics section in the factory service manual?

 

[wolfnaz]

SES & sys warnings

Replacing the ECM was a waste of money.

Have you reviewed the CCM diagnostics section in the factory service manual?

No i haven't....i have a Haynes manual...

 

[Hib Halverson]

Throw the Haynes Manual in the trash. They are useless for any type of diagnosis of the car's electronics and are questionable for what they cover--which is not much.

If you are going to attempt repair by DIY, you first need a factory service manual.

When the "SYS" flashes in the IPC, that usually means a problem with the CCM.

Start by verifying the battery, battery cables and the alternator are functioning properly. Check the ECM grounds and tighten and/or clean if necessary. On an L98, the ECM ground connects to a big bolt screwed into the block near the oil filter.

BTW: your email address blocks private email from me to you.

 

[sal826]

Sorry, I don't mean to hijack this thread, but what are some classic signs of ECM issues? My engine runs fine, then when I shut it off and re-start, it's almost impossible to start back up. The RPM's jump up and down, and then it will cut out over and over.