Is there a way to pull the computer codes from an '89 300E without a scanner or other special instrument? I don't have a problem yet -- just want to be prepared.

 

SELF-DIAGNOSTICS on your car (this is only for the California version though) This may help someone, so I'll post it anyway. Hope fully it'll help you too.

1. Turn the ignition to the run (on) position.

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Diagnostic Connector

2. Depress the push button #2 for 2 - 4 seconds.
* The LED will commence with (blink) impulse readout.
* The fault will be indicated by the number of LED impulses. Take note of the number of impulses.
* After the fault code has been displayed the LED will remain lit.

3. Repeat step 2 until all faults are indicated. The LED will remain on steady after all fault codes have been displayed.

* Refer to the FAULT CODES CHART for faults, (the picture below)

4. Repair the indicated faults. Be sure to turn the ignition switch to the off position before disconnecting connectors or components unless otherwise directed by testing procedures. Failure to do so may set new codes in the ECU memory.

5. After repairs have been completed clear the memory and repeat the test sequence. If all of the faults have been corrected the LED will blink once, (code 1, no faults present).

* If the push button #2 is depressed again for 2 - 4 seconds the control unit will be switched over to on/off ratio output for testing the lambda control.

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CLEARING CODES
NOTE: Each fault code stored in memory must be cleared individually.
1. Turn the ignition to the run (on) position.
2. After the fault code has been displayed, wait 2 seconds and then press the push button #2 for at least 6 seconds.
* The LED will blink once, indicating that the fault code has been cleared. Continue until all of the codes are cleared.