DTC 4-1-9

DTC 4-1-9. POWER STAGE EMITTING FAULTY DIAGNOSTIC SIGNAL





- Condition for DTC:
If the diagnostic signal from the passenger compartment fan power stage is missing or faulty, the control module records the fault and stores the DTC.

- Cause of fault:
Open circuit in wire across control module and passenger compartment fan power stage or internal fault in passenger compartment fan power stage.

- Symptoms:
Fault warning to driver. LEDs by A/C and REC buttons flash for 20 sec. Control module shuts off passenger compartment fan.

Connect Test Unit To Control Module:





- Ignition off.
- Connect test unit between control module and A/C system connector and check ground (GND) points.
- Go to the next step "Check Diagnostic Signal From Power Stage".

Check Diagnostic Signal From Power Stage:








- Ignition on.
- Connect a voltmeter across # 6 (0 V) and # 27.
- If value is OK, voltmeter should read 3 V.
- If voltmeter reads 0 V, open circuit in wire, wire shorted to 0 V or fault in power stage. Go to the step "Check Wire For Diagnostic Signal".
- If voltmeter reads 1 V, no control signal to power stage. DTC 4-1-8
- If voltmeter reads 4 V, overcurrent from power stage. Fault in power stage overcurrent protection or passenger compartment fan. Check passenger compartment fan. DTC 4-1-1
- If voltmeter reads 12 V, wire shorted to 12 V. Check wire between wire connector pin 2A and connector A pin A:27 to control module for short. Checking Wires
Rectify short.
Check DTC. Test Procedures

Check Wire For Diagnostic Signal:








- Ignition off.
- Disconnect the 4-pin connector from power stage.
- Check wire between connector pin 2A and connector A pin A:27 to control module for short to GND or open circuit. Checking Wires
- If there is a fault in the wire:
Rectify fault.
Check DTC. Test Procedures
- If wire OK, go to the next step "Check Power Supply To Power Stage".

Check Power Supply To Power Stage:








- Refit 4-pin connector to power stage.
- Ignition on.
- Connect a voltmeter across # 6 (0 V) and # 5. Voltmeter should read 12 V.
- If value is OK, go to the next step "Check Wire For Power Supply".
- If value is not OK, if voltmeter reads 0 V, wire is shorted to 0 V.
Check wire between wire connector pin 3A and connector A pin A:5 to control module for short. Checking Wires
Rectify short.
Check DTC. Test Procedures

Check Wire For Power Supply :








- Ignition off.
- Disconnect 4-pin connector from power stage. Connect an ohmmeter between # 5 and wire connector pin 3A. Ohmmeter should read 0 ohm.
- If value is OK:
Disconnect power stage. Service and Repair
Replace power stage and refit in reverse order.
Check DTC. Test Procedures
- If value is not OK, if resistance is infinite, there is an open circuit in the wire. Check wire between wire connector pin 3A and connector A pin A:5 to control module for open circuit. Checking Wires
Rectify open circuit.
Check DTC. Test Procedures