Component Tests and General Diagnostics

Checking the supply voltage/ground terminal

Checking the supply voltage/ground terminal

Power supply electrical power steering module (EPS)
The electrical power steering module (EPS) is powered (30-supply) via a power supply input on the control module and by a 15-supply via the ignition switch to a power supply input on the control module.

Note! There is no wiring on the electrical power steering module (EPS) for connecting the breakout box. It is therefore important when any measurements are carried out that great care is taken to prevent short-circuits, damage to connectors, etc.

Power supply (30-supply)
Power input terminal #B1 is supplied with +30 from the battery via a fuse. It will not be possible to activate the power steering function if there is an open-circuit.

Checking supply voltage (30-supply)
Check the power supply cable from the battery to the electrical power steering module (EPS) terminal #B1. 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.

Note! In the event of a damaged fuse, check the circuit. Check for a short-circuit before replacing the fuse. Any damage to the cable insulation can also cause intermittent or permanent short-circuits.

Power supply from ignition switch (15-supply)
Power input terminal #A1 is powered by +15-supply via the ignition switch and is fused in the relay/fusebox in the engine compartment and in the central electronic module (CEM). It will not be possible to activate the power steering function if there is an open-circuit.

Checking the power supply from ignition switch (15-supply)
Check the power supply cable from the battery via the ignition switch to the electrical power steering module (EPS) terminal #A1. Check for an open-circuit. Check for loose connections. Check for contact resistance. Check for oxidation. Check the fuse. The voltage should be approximately battery voltage at ignition on and low at ignition off.

Ground terminal
The electrical power steering module (EPS) has a ground input. The ground input from the control module is a power ground. The ground input is connected to a ground terminal in the car body. See the relevant wiring diagram for further information about ground terminals.

Checking ground terminal
Check the ground lead between the electrical power steering module (EPS) terminal #B2 and the ground terminal. Check for an open-circuit. Check for loose connections. Check for contact resistance. Check for oxidation.
Remedy as necessary.

Other information
- Checking wiring and terminals Checking Wiring and Terminals
- Signal specification Signal Description, Electrical Power Steering Module (EPS)
- See the relevant wiring diagram for information about circuits and ground terminals in the bodywork.





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