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 (C105) HVAC MUX Control circuit.

POSSIBLE CAUSES
- (C105) HVAC MUX control 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 (C105) HVAC MUX CONTROL 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 (C105) HVAC MUX Control 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 (C105) HVAC MUX CONTROL CIRCUIT FOR A SHORT TO VOLTAGE\




Turn the ignition off.
Disconnect the Instrument Cluster C2 harness connector.
Turn the ignition on.
Measure the voltage of the (C105) HVAC MUX Control circuit.

Q: Is the voltage above 0.2 volts?

YES: Repair the (C105) HVAC MUX Control 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