Part 2

Check the start system

Checking the starter motor relay





Checking the starter motor relay

Checking the starter motor relay

Note! The test requires that the battery is trouble-free and that no relevant diagnostic trouble codes are stored for the symptom.

- The signal chain to the starter motor can be checked quickly by short-circuiting the relay connections to the starter motor.
- For vehicles with automatic transmission:
The gear selector shall be in position P or N.
- For vehicles with manual transmission:
The gear lever shall be in neutral position.
- Parking brake applied.

Warning! In case of short-circuiting, the starter motor shall run.Be careful.

Caution! Use two cables with suitable cable terminal when short-circuiting so that the spark does not damage the relay socket.

Ignition off.
Remove the starter motor relay and short-circuit the relay socket #3(30) with #5(87), that is, the relay circuit.

Note! Do not bridge directly in the relay socket.Contacts may be damaged.

If the starter motor runs now then there is no malfunction of the power part in the circuit.

Other information
- For further information about the fuses and relays, see the Wiring Diagram.





Does the starter motor run when the relay is short-circuited?

Yes - Checking relay and start relay control signal

No - Checking the wiring

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Checking relay and start relay control signal

Caution! Avoid touching the pins in the control module and the corresponding connector on the cable harness.There is a risk of static discharge which could damage the control module.Discharge yourself and tools to be used by holding the tool's metal part and touching a body part on the car just before starting to work.

- It is possible to deduce whether the fault is in the wiring or in the relay by connecting a electrician's screwdriver over the relay socket coil.
- For vehicles with automatic transmission:
The gear selector shall be in position P or N.
- For vehicles with manual transmission:
The gear lever shall be in neutral position.
- Parking brake applied.
Connect a test probe between relay connection #1(86) and #2(85) on the relay socket.
Turn the ignition to start position (ignition position III) and observe the light.
If test probe lights up, replace the relay.

If test probe does not light up:
- Check fuses.
- Check the cable between the ignition's 50-feed #B2 and Central Electronic Module (CEM) #A42 for short-circuiting to ground and open circuit.
Check the cable between Central Electronic Module (CEM) #E9 and the relay socket #1(86) for short-circuit to ground and open circuit.
- Check the cable between relay socket #2(85) and Engine Control Module (ECM) for short-circuit to voltage and open circuit.
- Check the connector for the ignition for contact resistance as well as damage to pins and connections.
Check the connector for the Central Electronic Module (CEM) with regards to contact resistance as well as damage to pins and connections.
Check the connector for Engine Control Module (ECM) for contact resistance as well as damage to pins and connections.
Remedy as necessary.

Other information
- See Connecting breakout box for Central Electronic Module (CEM).
- See Connecting breakout box for Engine Control Module (ECM).
- See Signal specification for Central Electronic Module (CEM).
- See Signal specification for Engine Control Module (ECM).
- For connecting test probe, use loose flat pins.
- For information about the cable routing, see the relevant Wiring Diagram.
- For further information about the fuses and relays, see the Wiring Diagram.
- Checking wiring and terminals Checking Wiring And Terminals





Was a fault detected?

Yes - Verification

No - ???

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Checking the wiring




- Ignition off.
- For vehicles with automatic transmission:
The gear selector shall be in position P or N.
- For vehicles with manual transmission:
The gear lever shall be in neutral position.
- Parking brake applied.
Maintain the short-circuit between relay socket #3(30) with #5(87).
Check that there is power supply to the starter motor #6/25:2(#A1).
Check that the voltage is approximately battery voltage.

If there is no voltage supply to the starter motor terminal #6/25:2(#A1):
- Check fuses.
- Check the cable between connector 64/90 and starter motor #6/25:2(#A1) for short-circuit to ground and open circuit.
- Check the connector to the starter motor terminal #6/25:2(#A1). Check for contact resistance and damage to pins and connections.
Check that there is a power supply to the starter motor terminal #6/25:1(#B1).
Check that the voltage is approximately battery voltage.

If there is no voltage supply to the starter motor terminal #6/25:1(#B1):
- Check fuses.
- Check the voltage feed cable between the battery and starter motor #6/25:1(#B1) for short-circuit to ground and open circuit.
- Check the connector to the starter motor terminal #6/25:1(#B1). Check for contact resistance and damage to connections.
Remedy as necessary.

Other information
- See Connecting breakout box for Central Electronic Module (CEM).
- See Connecting breakout box for Engine Control Module (ECM).
- See Signal specification for Central Electronic Module (CEM).
- See Signal specification for Engine Control Module (ECM).
- For information about the cable routing, see the relevant Wiring Diagram.
- For further information about the fuses and relays, see the Wiring Diagram.
- Checking wiring and terminals Checking Wiring And Terminals





Was a fault detected?

Yes - Verification

No - ???

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Other fault-tracing
DONE - DONE

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Verification
Verification
VERIFIED - VERIFIED

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FAULT FOUND - ???

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Checking the starter motor





Checking the starter motor

Checking the starter motor

Note! To carry out this test, the battery must be fault free and the starter motor relay must be checked and there must be no diagnostic trouble codes (DTCs) stored for the symptom.

Warning! If the engine cooling fan is running, wait until it has stopped.




- Ignition off.
- For vehicles with automatic transmission:
The gear selector shall be in position P or N.
- For vehicles with manual transmission:
The gear lever shall be in neutral position.
- Parking brake applied.
- The function of the control solenoid must be checked by temporarily bridging the power supply between terminal #6/25:1(#B1) and the control signal for the starter motor relay terminal #6/25:2 (#A1).
The control solenoid must click and the starter motor must turn.

Other information
- For information about the cable routing, see the relevant Wiring Diagram.
- For further information about the fuses and relays, see the Wiring Diagram.





Does the starter motor turn?

Yes - Voltage drop in wiring to starter motor

No - Checking the starter motor

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Voltage drop in wiring to starter motor








- Ignition off.
- Reinstall the connectors, components etc.
- Connect a voltmeter to starter motor terminal #6/25:2(#A1).
- Check the voltage to the starter motor terminal #6/25:2(#A1) in the start position (ignition position III).
If the voltage drops below approximately 9 V, there is a voltage drop in the wiring circuit to the starter motor.

Select an option:
1. Malfunction was found in the test, that is, the voltage dropped too low in the start position.
2. No malfunction was found in the test, that is, the voltage did not drop too low in the start position.

Other information
- For information about the cable routing, see the relevant Wiring Diagram.
- For further information about the fuses and relays, see the Wiring Diagram.






1 - Check the voltage drop in the starter motor and battery circuit

2 - ???

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