Pinpoint Test D: DTC 4-4
Climate Control System
Pinpoint Test D: DTC 4-4
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information Electrical Diagrams.
Normal Operation
A 5-volt reference voltage is supplied to the sensors and actuators from the HVAC module.
- DTC 4-4 (Feedback Reference Circuit/Performance)- The module senses less than expected voltage on the reference voltage circuit, indicating a short directly to ground or the module senses greater than expected voltage on the sensor reference voltage circuit, indicating an open or a short directly to voltage.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- HVAC module
PINPOINT TEST D : DTC 4-4
D1 CHECK THE REFERENCE VOLTAGE CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: HVAC Module C228A.
- Measure the resistance between ground and HVAC module C228A-12, circuit CH232 (WH/BN), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to D2.
No
REPAIR circuit CH232 (WH/BN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
D2 CHECK THE REFERENCE VOLTAGE CIRCUIT AND THE SIGNAL RETURN CIRCUIT FOR A SHORT TOGETHER
- Measure the resistance between HVAC module C228A-12, circuit CH232 (WH/BN), harness side and HVAC module C228A-2, circuit CH233 (VT/BN), harness side.
Is the resistance greater than 100 ohms?
Yes
GO to D4.
No
GO to D3.
D3 CHECK THE ACTUATORS
- Measure the resistance between HVAC module C228A-2, circuit CH233 (VT/BN), harness side and HVAC module C228A-12, circuit CH232 (WH/BN), harness side.
- While measuring the resistance, disconnect the following components one at a time, in order. Stop disconnecting components if the measured resistance rises above 100 ohms.
- Defrost/panel/floor door actuator C236
- Temperature blend door actuator C2092
Did the resistance rise above 100 ohms?
Yes
INSTALL a new actuator (the last one to be disconnected). CONNECT the actuator electrical connector before the HVAC module connector(s). This allows the actuator to be calibrated when the HVAC module is reconnected. TEST the system for normal operation.
No
REPAIR circuits CH233 (VT/BN) and CH232 (WH/BN) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
D4 CHECK THE REFERENCE VOLTAGE CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and HVAC module C228A-12, circuit CH232 (WH/BN), harness side
Is any voltage present?
Yes
REPAIR circuit CH232 (WH/BN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to D5.
D5 CHECK THE RETURN CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and HVAC module C228A-2, circuit CH233 (VT/BN), harness side
Is any voltage present?
Yes
REPAIR circuit CH233 (VT/BN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to D6.
D6 CHECK THE REFERENCE VOLTAGE CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Temperature Blend Door Actuator C2092.
- Measure the resistance between ground and HVAC module C228A-12, circuit CH232 (WH/BN), harness side and temperature blend door actuator C2092-2, circuit CH232 (WH/BN).
Is the resistance less than 5 ohms?
Yes
GO to D7.
No
REPAIR circuit CH232 (WH/BN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
D7 CHECK THE HVAC MODULE CONNECTION
- Disconnect all the HVAC module connectors.
- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new HVAC module. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. TEST the system for normal operation.