P1456

DIAGNOSTIC TROUBLE CODES P1455, P1456
A/C relay, output from control module low/high,
No continuity or shorting to ground/batt+.

Fault Symptom.
No A/C function.

Condition
No continuity or shorting to ground/batt+ in the circuit to pin 33.

Diagnostic Procedure.
1. Activate the "AC RELAY" function in the "ACTIVATE" menu and listen to check whether the A/C relay is working.

If the relay works as it should, continue at "Before Control Module Replacement" for further diagnostic instructions. Before Replacing A Control Module
If the relay does not work, continue as described below.

2. With the ignition switched OFF, connect a BOB between the control module and its cable.
With the ignition switch in the DRIVE position and the A/C function activated, check whether current is present on pin 41 of the MOTRONIC control module.

If it is, proceed to step 2.
If it is not, check the A/C function/wiring as needed.

3. Start the engine and check whether the control module grounds pin 33 when current is present on pin 41 (delay in the control module for idling compensation).

If the control module grounds pin 33, check the A/C function/wiring diagrams as needed.
If the control module does not ground pin 33, continue at "Before Control Module Replacement" for further diagnostic instructions. Before Replacing A Control Module