LT4 96 LT4 - $%&#@!! SES Light

[jcs44]

I could use some help with ideas why my SES light keeps coming on. The car received a new water pump and distributor cap/rotor, and new plugs about a year ago. The car has 40K on it and is stock. Ever since, the SES light will come on, usually after the car has sat for a few days. The light comes on blinking at first and then stays on steady (it will go thru this cycle a few time). Usually, it goes off by the end of the day. The only code it ever reads is 0300 - random misfire. My Vette shop has more disgnostics stuff than any Chevy dealer and specializes in C4s. I trust them completely. He has run it hot, cold, and with diagnostic equipment attached while driving. Nothing comes up that is an obvious cause of the misfire. Everything has been checked multiple times. He has a complete computer baseline on the car so he can see if anything changes; and it hasn't.

Any ideas? mad:crazy;help
JCS44
96 LT4 Roadster, triple black

 

[Hrtbeat1]

usually after the car has sat for a few days. Usually, it goes off by the end of the day.

Sounds like a weak or not fully charged battery.

The random misfire could be the optispark. Mine will occasionally get that during high RPM's ... above 5200.

 

[jcs44]

Well, this car will run up to the redline with no problem. The SES light usually comes on at about 2000 rpm just cruising along in 5th. Battery is fairly new and reads 14.1V.

JCS44

 

[JAKE]

Well, this car will run up to the redline with no problem. The SES light usually comes on at about 2000 rpm just cruising along in 5th. Battery is fairly new and reads 14.1V.

JCS44

Pull the stored code(s) to show you what's causing the problem.

Just use a bent paper clip or a short length of wire, insert the ends into the diagnostic link located under the driver's side of the dash. Turn the ignition key to "ON" but don't start the engine. Write down the code(s) that blink.

If you need a step-by-step let me know and I'll post it. However, the procedure may already be posted on this Forum. A Search should turn it up for you.

Jake

 

[jcs44]

Jake,

I have a code reader and the only thing I get when the SES come on is 0300, random misfire. This is pretty non-specific as to the cause.

John

 

[JAKE]

Jake,

I have a code reader and the only thing I get when the SES come on is 0300, random misfire. This is pretty non-specific as to the cause.

John

Okay, so now you need to look in your FSM and follow the step by step instructions to track down the cause. The FSM will show you what to check and how. BINGO!

Jake