DTC ECM-902B

Condition







The control modules communicate with each other in a network via a standardized serial communication method - CAN (Controller Area Network).

Diagnostic trouble code (DTC) ECM-902B, signal too high, is stored if the electronic throttle module (ETM) has not transmitted a signal on the control area network (CAN) to the engine control module (ECM) within approximately 1 second after the ignition is switched on.

Diagnostic trouble code (DTC) ECM-902B, signal too low, is stored if the electronic throttle module (ETM) has not transmitted a request to the engine control module (ECM) to shut-off the system relay within a certain time of the ignition being switched on.

Substitute value
- the accelerator pedal (AP) is ignored when braking
- the cruise control switched off
- the engine speed (RPM) is limited using fuel shut off. The maximum permitted engine speed depends on the accelerator pedal (AP) position
- the electronic throttle module (ETM) follows the pulse width modulation (PWM) accelerator pedal signal directly, the control signal via the control area network (CAN) is ignored.

Possible source

Signal too high
- delayed system relay start when the ignition is switched on
- the power supply to the electronic throttle module (ETM) when the ignition is switched on (signal too high), or when running (signal missing)
- loose connections or contact resistance in the terminals for the CAN
- interference in the control area network (CAN) wiring
- defective control area network (CAN) wiring
- defective electronic throttle module (ETM)
- another node in the Control area network (CAN) is defective.

Signal too low
- defective electronic throttle module (ETM).

Fault symptom[s]
- the accelerator pedal (AP) is ignored when braking
- the cruise control cannot be activated
- uneven idle
- jerks during engine braking.