Vehicle Electrical System (BNSG)

Fault code 0668

Vehicle voltage, terminal 30

Diagnostic conditions
- Ignition on
- Internal control module function test

Possible causes of fault

NOTE:
In the event of an open circuit in the measuring leads, the vehicle electrical system control module receives an 'implausible signal', which is stored as a single fault in the fault memory. This approach is intended to speed up fault localisation. The only exception is the 'Rain/light sensor' fault, which is also stored when the voltage is less than 9.0 V.
- 'implausible signal' No emergency start detection and no other fault codes stored in the fault memory except 'Vehicle voltage, terminal 30'(see Note).

Affected pins
Plug 'P' on vehicle electrical system control module:
- Pin 4 'input for positive measurement of vehicle electrical system battery via fuse F9 in current distributor'
- Pin 9 'input for negative measurement of vehicle electrical system battery/ground pin 23'

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.