Ignition - Erratic Warning Light or Engine Performance

Group
2

Number
8906

Model
911 Carrera 4

Part Identifier
2853

October 6, 1989

Subject:
Erratic Warning Light Operation and/or Engine Performance

911 Carrera 4

Model Year 1989

Condition:

- Warning symbols in the instrument cluster light up (ABS, 4 wheel drive lock, central warning) and/or warning buzzer comes on separately or several simultaneously, sporadically or continuously.

- Various faults in DME control unit memory.

- Engine performance problems and/or incorrect tachometer display.

Cause:

- The cause could be arcing or jumping of ignition sparks because of incorrectly mounted, loose spark plug connectors or damaged ignition leads.

Repair Instructions:

The function of ignition circuits 1 (top) and 2 (bottom) should be checked as follows:

With the ignition turned off, pull off final stage plug for ignition circuit 2 and start engine. If engine performance is normal and no warning symbols light up in instrument cluster, ignition circuit 1 is okay

If engine performance is not okay and/or warning symbols light up, eliminate faults in ignition circuit 1.

When connecting spark plug connectors it is important to make sure that engagement is noticed while pressing on.

Repeat test for ignition circuit 2 by pulling off final stage plug for ignition circuit 1.

After repairs, cancel any faults stored in the DME memory according to the procedures in section 03 of the Workshop Manual.

Test drive car and read out fault memory again. If warning symbols light up again or faults are stored in the DME control unit, the displayed system should be checked and repaired.

Note:
The function of ignition circuits 1 and 2 should be checked every time the ignition wires are pulled off during repair and maintenance work. Refer to 911 Carrera 4 Workshop Manual Volume 1, page 03-25 for ignition circuits checking instructions.

Also refer to Technical Bulletin Group 2, Number 8905, dated October 6, 1989.