midbvette

My 89 suddenly showed a "service engine soon" display. It does not show at engine start up, but only after warming up for about ten minutes. I jumped the ALDL connector at pins "A & B", only to read a
continual code 12 which never ends. In other words, nothing but code
12 appears. I am trying to smog car in California and won't have a chance of passing showing the flashing display. Car seems to be running fine.


Thanks for any suggestions

WVZR-1

Does it display the light "STEADY ON" when ignition is "KEY-ON" but NOT CRANKED? Have you actually attempted a "reset" to clear codes?

midbvette

Light is not "Steady On", but rather flashing intermittently. I have not
tried a reset. Is that done by disconnecting battery terminal?

MrWillys

If you don't have a solid light at key on you may have an ECM or CalPak error.

midbvette

Sorry, I misunderstood. With ignition in "key on" position (engine not running), light is solid. It only flashes after 10 mins of driving and continues to flash until shut down. Jumping the ALDL at this point produces only code 12 and nothing else.

MrWillys

Why don't you ask your auto parts store to read it for you. I know EGR will set a code only when it's called for and go out when not called for.

Kevova

Most parts stores can't read obd1 codes. If ALDL is jumped while engine is running check engine light will flash indicating O2 sensor flipping from rich to lean. I would check wire from ALDL to ECM for chaffing or or shorting to ground. If there no problem found I would replace ECM