DTC 1-1-2

1-1-2 FAULT IN ECM

Conditions for DTCs
^ If the control module detects a fault in the ROM/EPROM or RAM memory circuits, the circuit for the Engine Control Module's (ECM) temperature sensor, knock control circuit (zero test, short term fuel trim test) or Engine Coolant Temperature Sensor (ECT) circuit's Negative Temperature Coefficient (NTC) coupling, DTC 1-1-2 is set.

Substitute values
^ Fault in the ROM/EPROM memory circuit, RAM circuit or circuit for the ECM temperature sensor:
- No substitute value.
- Temperature sensor, fan 1/2 speed.

^ Fault in knock control circuit (zero test, short term fuel trim test):
- Dwell angle reduced for safety reasons.
- Only initial charge pressure permitted.
- Increase in injected fuel quantity to reduce combustion temperature.

^ Fault in Engine Coolant Temperature Sensor circuit's NTC coupling:
- At start, assumes a substitute value of +20°C (68°F); some time after start up, the assumed value is +83°C (181°F).
- Engine cooling fan starts at half speed.
- Idle air trim inhibited.
- Long term fuel trim inhibited.
- Limitation of charge air pressure.

Fault sources
^ Fault in ECM's ROM/EPROM or RAM circuits.
^ Fault in ECM's circuit for ECM temperature sensor.
^ Fault in ECM's knock control circuit.
^ Fault in ECM's circuit for ECT sensor (NTC coupling).

Fault Symptom
^ A fault in the knock control circuit will lead to impaired performance from initial charge pressure limit.

TESTING PROCEDURE





Other DTCs
^ Read the other DTCs.

If DTC 4-3-2 and 5-1-3 are stored:
- Fault tracing according DTC 5-1-3, Temperature warning level 2, followed by check of status message.
If none of the above DTCs are stored:
- Check status message.





Check Status Message
^ Check current Status Message.

Memory Error RAM:
If Status message is: Permanent fault, faulty signal.
- Proceed to: PERMANENT FAULT section below.
If Status message is: Intermittent fault, faulty signal.
- Proceed to: INTERMITTENT FAULT section below.

Memory Error ROM/EPROM:
If Status message is: Permanent fault, faulty signal.
- Proceed to: PERMANENT FAULT section below.
If Status message is: Intermittent fault, faulty signal.
- Proceed to: INTERMITTENT FAULT section below.

Control Module (ECM) Temperature Sensor:
If Status message is: Permanent fault, signal too high.
- Proceed to: PERMANENT FAULT section below.
If Status message is: Permanent fault, signal too low.
- Proceed to: PERMANENT FAULT section below.
If Status message is: Intermittent fault, signal too high.
- Proceed to: INTERMITTENT FAULT section below.
If Status message is: Intermittent fault, signal too low.
- Proceed to: INTERMITTENT FAULT section below.

Knock Control:
If Status message is: Permanent fault, zero test.
- Proceed to: PERMANENT FAULT section below.
If Status message is: Permanent fault, short term fuel trim test.
- Proceed to: PERMANENT FAULT section below.
If Status message is: Intermittent fault, zero test.
- Proceed to: INTERMITTENT FAULT section below.
If Status message is: Intermittent fault, short term fuel trim test.
- Proceed to: INTERMITTENT FAULT section below.

NTC Coupling:
If Status message is: Permanent fault, faulty signal.
- Proceed to: PERMANENT FAULT section below.
If Status message is: Intermittent fault, faulty signal.
- Proceed to: INTERMITTENT FAULT section below.

PERMANENT FAULT





^ Switch Ignition OFF.
^ Test with a new control module. Replace the control module.

INTERMITTENT FAULT





^ The control module registered a fault on a previous occasion.
^ Switch Ignition ON.
^ Erase any DTCs.