Rough Road Detection

Replacement ECM's are supplied blank and must learn the immobilisation ECU security code for the vehicle to which it is fitted. When the ECM is connected to the vehicle, TestBook is required to enable the ECM to learn the immobilisation ECU code. If a new immobilisation ECU is fitted, the ECM will need to learn the new security code using TestBook. A procedure must be followed when replacing the ECM or immobilisation ECU. This procedure is detailed in the Security Description and Operation section. SECURITY, DESCRIPTION AND OPERATION, Description.

Rough Road Detection

MEMS 3 has a misfire detection facility which is part of the On-Board Diagnostics (OBD) system. Misfire detection is disabled when the ECM senses that the vehicle is on a 'rough road'. The system software receives rough road signal outputs from the ABS ECU and can disable misfire detection to prevent incorrect faults being logged by the ECM.

The 'rough road' signal is passed from the ABS ECU to ECM pins 65 and 79 on the CAN bus. The CAN message is a measure of the maximum wheel acceleration from any one of the four wheel sensors, which is updated by the ABS ECU every 20 ms.

Fuel Shut-off Switch

The fuel shut-off switch is located in the engine compartment to the rear of the LH suspension turret. In the event of a sudden deceleration the switch removes the power supply to the fuel pump relay, stopping the fuel pump.

The fuel shut-off switch, when tripped can be reset by depressing the rubber top of the switch. The switch receives a power supply from fuse 10 in the engine compartment fusebox. The supply is passed through the switch to the contacts of the fuel pump relay in the engine compartment fusebox. the supply from the switch is also passed to the Central Control Unit (CCU) to unlock the doors in the event of a collision causing the fuel shut-off switch to be tripped.

WARNING: Ensure there are no fuel leaks and confirm the integrity of the fuel system before resetting the fuel shut-off switch.

Throttle Pedal Switch

The throttle pedal switch is located at the top of the pedal box and secured in a cut-out hole in the fabrication. The switch is a proximity type Hall effect switch which senses a target located on the throttle pedal. The switch is connected on a single wire to pin 77 of ECM connector C0913.

The switch is normally open when the throttle pedal is at rest. When the throttle pedal is depressed, the target on the pedal moves away from the switch causing the switch to close and complete an earth path from the ECM. This is sensed by the ECM which uses the signal as a throttle status to detect for stuck throttle when using Hill Descent Control (HDC). The pedal status is compared with the inputs from the TP sensor to confirm that the throttle is being depressed.