Component Tests and General Diagnostics

Checking the power supply and ground terminal

Power supply Headlamp Control Module (HCM)
Headlamp Control Module (HCM) is supplied with voltage via a voltage input on the control module.
When the ignition is on, the power input is powered and the control module is in active mode.
- Power input terminal #C1:10 is supplied with voltage via a fuse from the system relay. This power input governs the supply of power to the Headlamp Control Module (HCM). It will not be possible to activate the control module if there is an open-circuit.

Checking the power supply
Check the power supply cable from the system relay to the Headlamp Control Module (HCM) terminal #C1:10. Check for an open-circuit. Check for loose connections, contact resistance and oxidation. Check the fuse. The voltage must be approximately battery voltage.

Ground terminal Headlamp Control Module (HCM)
Headlamp Control Module (HCM) has a ground input. The ground input from the control module is connected to a ground terminal in the body via a ground lead. See the relevant wiring diagram for further information about the ground terminal.
- Ground input #C1:7 is power ground and is connected to the earth connection in the body.

Checking the ground terminal
Check the ground cable between the Headlamp Control Module (HCM) terminal #C1:7 and the ground terminal. Check for an open-circuit. Check for loose connections. Check for contact resistance and oxidation. At ignition on, the voltage-drop between Headlamp Control Module (HCM) ground connection and chassis connection may not be greater than 0.5 V.
Remedy as necessary.

Other information
- Signal specification Pinout Values and Diagnostic Parameters
- See the relevant wiring diagram for information about circuits and ground terminals in the bodywork.
- Checking wiring and terminals Checking Wiring and Terminals. Permanent Faults





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