Topic: The service engine soon light is on..how do you check the codes?
in Forum: C4 Cooling and Heating Systems
Check for codes, and then let us know what it has....
btw..it should always start with a code 12...this simply means the ECM has gone into diagnostic mode.
It's commonly referred to as the "DLC""....it's the connector where a scan tool would be plugged in....located under the dash on the drivers side...use a paper clip to connect the two terminals together.
Yes, it should always display Code !2. But Code 12 really means "No distributor reference pulses received".
Because the engine is not running, there are no reference pulses, and Code 12 displays. When engine is not running, and NOT in diagnostic mode, CEL is lit solid. Like it would be for any other soft-code. A soft code is one that turns off the light when the conditions to set the code cease to exist. Start the engine, and reference pulses ARE received, and the "Code 12" goes away, and the light goes out.
The light is always lit with the key on, engine off. Because there is always a Code 12 in this state. Short A&B to enter diagnostic mode, and the light flashes the code. That's what indicates you've entered code-retrevial mode: The flashing CEL.
|UPDATED|8/17/2012 11:11:16 PM (AZT)|/UPDATED|
Yes, it should always display Code !2. But Code 12 really means "No distributor reference pulses received".
Because the engine is not running, there are no reference pulses, and Code 12 displays. When engine is not running, and NOT in diagnostic mode, CEL is lit solid. Like it would be for any other soft-code. A soft code is one that turns off the light when the conditions to set the code cease to exist. Start the engine, and reference pulses ARE received, and the "Code 12" goes away, and the light goes out.
The light is always lit with the key on, engine off. Because there is always a Code 12 in this state. Short A&B to enter diagnostic mode, and the light flashes the code. That's what indicates you've entered code-retrevial mode: The flashing CEL.
It's the wierdest thing. I checked under the dash and I don't see anything that looks like the plug in. I know on other cars when you get the emisions tested they use the plug in. My 85 seems to be missing that port. Is it possible that it's been relocated? I took the plastic piece down from under the steering column and I don't see anything.
Trouble Code 43 indicates that there may be a malfunction in the Electronic Spark Control (ESC) circuit.
ESC is used to sense spark knock (pinging) and retard the timing to eliminate it. A knock sensor (located at the rear of the engine block) sends signals to an ESC module which then signals the ECM that knocking is being detected. The ECM will retard the timing by as much as 20 degrees in 1 degree increments. A loss of knock sensor signal or loss of ground at the ESC module will cause the signal at the ECM to remain high. The ECM will act as if no knock is present, and may possibly result in engine damage, if there is detonation.
Loss of the ESC signal to the ECM will cause the ECM to constantly retard the timing to its maximum. This results in sluggish performance and a Code 43.
The conditions for setting this code are:
- Engine is running
- ESC input signal has been low more than 2.23 seconds
Typical causes for this code include:
1) Open or shorted knock sensor
2) Loose knock sensor
3) Excessive mechanical noise within engine
4) Improper or incorrectly installed PROM or CALPACK in the ECM or defective ECM
5) Intermittent open in the EST line to the ignition module
|UPDATED|8/18/2012 2:06:49 PM (AZT)|/UPDATED|