Ian C
03-04-05, 20:59
When things go wrong with engine components, sensors, etc. there is a chance that it's going to be a failure mode that your ECU will recognise. Usually, you'll know something has happened because the MIL (Malfunction Indicator Light, the red exclamation mark) lights up.
The ECU stores an error code so that you can check later what the problem is/was. Rather than requiring a bug diagnostics machine, you can use a simple paperclip, or a short loop of wire. You use this to bridge the connections E1 and TE1 in the diagnostics port ( Location, 4th thumbnail along (http://www.mkivsupra.net/vbb/showthread.php?t=35925) )
Update - Make sure you have de-immobilised your car! Some immobilisers stop the engine light from flashing.
This makes the ECU flash the orange check engine light (not the red MIL light) when the ignition is switched to position 2. If it's a regular flash then there are no stored codes. Otherwise it will blink a few times, pause, blink a few times, and then give a longer pause. That's one stored code, and the number of blinks is the digit, so:
blinkblinkblink pause blink pauuuuuse
Is code 31. You may have more than one stored code, so it'll work its way through them from lowest to highest. It will then loop back to the start again.
For example, if you had a misfire and you also had a problem with your speed delimiter you may find you got:
blink pause blinkblinkblinkblink pauuuuuse blinkblinkblinkblink pause blinkblink pauuuuuse repeat
Which is code 14 (problem in ignition circuit) and code 42 (No1 speed sensor problem)
These codes are stored indefinitely and only cleared when you reset the ECU in some way (fuse removal, battery disconnect/flatten). This means you may have some red herring codes stored if you are at the initial stages of diagnosing a problem, so resetting the ECU, triggering the problem, and then reading the codes is the best method.
-Ian
The ECU stores an error code so that you can check later what the problem is/was. Rather than requiring a bug diagnostics machine, you can use a simple paperclip, or a short loop of wire. You use this to bridge the connections E1 and TE1 in the diagnostics port ( Location, 4th thumbnail along (http://www.mkivsupra.net/vbb/showthread.php?t=35925) )
Update - Make sure you have de-immobilised your car! Some immobilisers stop the engine light from flashing.
This makes the ECU flash the orange check engine light (not the red MIL light) when the ignition is switched to position 2. If it's a regular flash then there are no stored codes. Otherwise it will blink a few times, pause, blink a few times, and then give a longer pause. That's one stored code, and the number of blinks is the digit, so:
blinkblinkblink pause blink pauuuuuse
Is code 31. You may have more than one stored code, so it'll work its way through them from lowest to highest. It will then loop back to the start again.
For example, if you had a misfire and you also had a problem with your speed delimiter you may find you got:
blink pause blinkblinkblinkblink pauuuuuse blinkblinkblinkblink pause blinkblink pauuuuuse repeat
Which is code 14 (problem in ignition circuit) and code 42 (No1 speed sensor problem)
These codes are stored indefinitely and only cleared when you reset the ECU in some way (fuse removal, battery disconnect/flatten). This means you may have some red herring codes stored if you are at the initial stages of diagnosing a problem, so resetting the ECU, triggering the problem, and then reading the codes is the best method.
-Ian