MTC 73

73-AC REQUEST OUTPUT SIGNAL TOO HIGH (MTC)

73 - AC Request Output Signal Too High (MTC):

WHEN MONITORED
With the ignition on.

SET CONDITION
If the A/C Heater Control detects voltage above 4.49 volts on the (C221) A/C Switch Sense circuit.

POSSIBLE CAUSES
- (C221) A/C switch sense circuit shorted to voltage
- Instrument cluster (CCN)
- A/C heater control

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. Refer to HVAC System Test (MTC) for stored DTC test procedures. HVAC System Test (MTC)

Diagnostic Test




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

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

Q: Is the voltage above 5.2 volts?

YES: Go To 2
NO: Replace the A/C Heater Control. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test




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

Turn the ignition off.
Disconnect the Instrument Cluster C3 harness connector.
Turn the ignition on.
Measure the voltage of the (C221) A/C Switch Sense circuit.

Q: Is the voltage above 0.2 volts?

YES: Repair the (C221) A/C Switch Sense circuit for a short to voltage. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the Instrument Cluster (CCN). Perform BODY VERIFICATION TEST - VER 1. Body Verification Test