Immobilizer - Implausible Operating Range

P1570

Immobilizer - Implausible Operating Range

Function
When the engine is first started up or after a Motronic reset, the DME control module communicates with the alarm system control module. If this communication takes place correctly, the engine can be started. If the communication is disturbed, the engine cannot be started. The starter is not triggered.

Diagnosis conditions
- Start condition
- Motronic reset

P1570-P1571:

Wiring Diagram







Diagnosis Procedure







1 Check signal wire for continuity.

1. Remove connector I of alarm system control module.
2. Connect special tool 9616 to wiring harness (DME control module connector).
3. Connect ohmmeter to special tool 9616, pin 88, and to alarm system connector I/23.
Display: 0 - 5 ohms

If Infinity ohm is displayed, remove connector X 2/3.

4. Connect ohmmeter to connector X 2/3, pin 6, on sleeve side and to special tool 9616, pin 88.
Display: 0 - 5 ohms

If Infinity ohm is displayed, repair wiring harness.

5. Connect ohmmeter to connector X 2/3, pin 6, on pin side, and to alarm control module connector I, pin 23.
Display: 0 - 5 ohms

If Infinity ohm is displayed, repair wiring harness.

2 Check signal wire for short circuit to ground.

1. Remove connector I of alarm system control module.
2. Connect special tool 9616 to wiring harness (DME control module connector).
3. Connect ohmmeter to special tool 9616, pin 88, and ground.
Display: Infinity ohm

If 0 - 5 ohms is displayed, check wiring harness for chafing and pinching damage.

3 Check signal wire for short circuit to B+.
1. Remove connector I of alarm system control module.
2. Connect special tool 9616 to wiring harness (DME control module connector).
3. Connect voltmeter to special tool 9616, pin 88, and ground.
Display: 0 V

If battery voltage is displayed, check wiring harness for chafing and pinching damage.