Heating & A/C System: 74

74-AC REQUEST OUTPUT SIGNAL TOO LOW





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

- When Monitored:
With the ignition on.

- Set Condition:
If the A/C Heater Control detects voltage below 1.51 volts on the (C221) A/C Switch Sense circuit.





NOTE: This DTC must be active for the results of this test to be valid. Do not perform this test if this DTC is stored. for stored DTC test procedures. Heating & A/C System

1. CHECK (C221) A/C SWITCH SENSE CIRCUIT VOLTAGE AT A/C HEATER CONTROL C1 HARNESS CONNECTOR




1. Turn the ignition off.
2. Disconnect the A/C Heater Control C1 harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (C221) A/C Switch Sense circuit.

Is the voltage below 4.8 volts?

Yes

- Go To 2

No

- Replace the A/C Heater Control.
- Perform the BODY VERIFICATION TEST Body Verification Test.

2. CHECK (C221) A/C SWITCH SENSE CIRCUIT FOR A SHORT TO GROUND




1. Turn the ignition off.
2. Disconnect the Instrument Cluster C3 harness connector.
3. Measure the resistance of the (C221) A/C Switch Sense circuit between ground and the A/C Heater Control C1 harness connector.

Is the resistance below 10K ohms?

Yes

- Repair the (C221) A/C Switch Sense circuit for a short to ground.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Go To 3

3. CHECK (C221) A/C SWITCH SENSE CIRCUIT FOR AN OPEN




1. Measure the resistance of the (C221) A/C Switch Sense circuit between the A/C Heater Control C1 harness connector and the Instrument Cluster C3 harness connector.

Is the resistance below 5.0 ohms?

Yes

- Replace the Instrument Cluster (CCN).
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Repair the (C221) A/C Switch Sense circuit for an open.
- Perform the BODY VERIFICATION TEST Body Verification Test.