P1944

P194400

Diagnosis information DME control unit

Radiator fans Activation

Diagnostic conditions
The control unit must be active in order to test internal function sequences and diagnosable inputs/outputs.
In the event of a fault, check whether the fault is permanently >present<. To perform the check, erase the fault memory, meet the diagnostic conditions and read out the fault memory again.
- Ignition on

Possible fault causes
- Short circuit to B+/ground/between lines or open circuit in the lines

Fault setting condition(s)
- PWM signal to Radiator fan control module Short circuit Voltage Battery
- PWM signal to Radiator fan control module Open circuit

NOTE:
Diagnosis/Fault finding.
- Check of the electrical wiring and plugs
- Current measurement shows a square-wave signal in OK case
- Voltage measurement of control line displays approximately the battery voltage
- Supply voltage U ~ 12 V