Component Tests and General Diagnostics

Checking the supply voltage/ground terminal

Power supply, the Suspension Module (SUM)
The suspension module (SUM) is powered via a power input. The control module is active at ignition switch position II.
The power input (C2-#1(#31)) is powered via the rear relay box. The suspension module (SUM) has no 30-supply and is completely cut of power in ignition switch position I.

Checking the power supply
Check the power supply cable from the battery, via the rear relay box, to the suspension module (SUM) terminal C2-#1 (#31). Check for an open-circuit. Check for loose connections. Check for contact resistance. Check for oxidation. Check the fuse. The voltage must be approximately battery voltage.

Ground terminal, Suspension Module (SUM)
Suspension module (SUM) has a ground input.
Ground input terminal (C2-#2(#32)) is power ground and is connected to the ground terminal in the car body.
See the relevant wiring diagram for further information about the ground terminal.

Checking the ground terminal
Check the ground lead between suspension module (SUM) terminal C2-#2(#32) and the ground terminal. Check for an open-circuit. Check for loose connections. Check for contact resistance. Check for oxidation. With the ignition on, the drop in voltage between the ground connection to the suspension module (SUM) and the ground terminal must not be greater than 0.5 V.
Remedy as necessary.

Other information
- Connecting the breakout box Connecting the Breakout Box, Suspension Module (SUM)
- Signal specification Signal Specification, Suspension Module (SUM)
- 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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