Fault Code 1800

Fault code 1800

Main light switch

Diagnostic conditions
- Ignition on
- Internal control module function test
- Switch position '0'
- Switch position 'parking light'
- Switch position 'dipped beam headlight'
- Switch position 'driving light assistant', only for 'driving light assistant' coding

Possible causes of fault
- 'implausible signal' With 'Ignition on' the dipped beam headlight comes on.

Affected pins
Plug 'A' on vehicle electrical system control module:
- Pin 5 'input from main light switch (headlight)'
- Pin 17 'input from main light switch (parking light)'
- Pin 19 'input from main light switch (dipped beam headlight)'

Diagnosis/troubleshooting

NOTE:
- Before replacing the control module, the ground connections, power supply and plug connections on the control module must be checked.
- When replacing the vehicle electrical system control module, observe the coding of the control module.
- After the test drive, read out the fault memory with the Porsche System Tester II No. 9588 again. Additional causes of faults that could damage the vehicle electrical system control module should be detected and remedied.