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BCM / B3940 05

Read the instructions below then start the fault diagnostic procedure.

Symptom: No heating in car when parking heater activated.

  B3940 05


Block Heater Relay Circuit, Open/Short to B+

Fault symptom

No heating in car when parking heater activated.

On-board diagnosis

Type of diagnosis:

Continuous

Enable criteria:

Ignition ON.
Relay not activated.

Fault criteria:

When the current on the output is 0A.

Checking the wiring harness

Move the wiring harness at several spots and in several directions to reveal intermittent breaks and short-circuits. Check switches, connectors and crimp connections for oxidation, retracted pins and pin clamping force.

Diagnostic help

Diagnosis regards:

Electrical fault in connecting leads or component.

Functions in the diagnostic tool related to the fault:

Activation:
Block Heater Relay
(See also description of readings/activations in diagnostic tool)