Why is my engine light comming on and off for my '87 Chevy Caprice?

mnkelly

Could be the PCV valve is bad or the vacuum hose or port is plugged. This happened to my 1990 chevy 350 TPI. The port in the throttle body was completely plugged and the service engine soon lit would come on after I drove it for a while. Usually the SES light is related to an emmision component so you should concentrate your search in those areas first.

Your 87 is a OBD-I system. It does not store the code past when you turn off the key in most cases. It does keep coming on due to self test showing that an emission system part is out of specs. Best to find someone whom has the ability to read the OBD-I codes and have that person read the code before the car is shut off next time the light is on. Most auto parts stores only read OBD-II (96 and newer) codes. Some may have a reader that can check the older cars.

Passenger side electric mirror could either be a faulty switch, broken wire for the up/down motor, or failed motor. Testing would have to be done to track down the problem.

Just now noticed that this thread is over a year and half old.:tongue: Hope he has it fixed by now.

77Impala said:

Your 87 is a OBD-I system. It does not store the code past when you turn off the key in most cases. It does keep coming on due to self test showing that an emission system part is out of specs. Best to find someone whom has the ability to read the OBD-I codes and have that person read the code before the car is shut off next time the light is on. Most auto parts stores only read OBD-II (96 and newer) codes. Some may have a reader that can check the older cars.

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Doesn't this year still respond to shorting the A and B pins together on the computer diagnostic connector under the dash and getting a flashing SES light with the stored codes? Also, I do remember that some codes are stored for a period of time after the SES turns off.

RMC said:

Doesn't this year still respond to shorting the A and B pins together on the computer diagnostic connector under the dash and getting a flashing SES light with the stored codes? Also, I do remember that some codes are stored for a period of time after the SES turns off.

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Yes it does. With my code reader that I use regularly I forgot that this could be done.:redface: Anyway the code reader makes the task so much simpler than having to count the flashes.:wink: