Pinpoint Test M: Temperature Control is Inoperative/Does Not Operate Correctly
Climate Control System
Pinpoint Test M: Temperature Control is Inoperative/Does Not Operate Correctly
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information Electrical Diagrams.
Normal Operation
The HVAC module supplies voltage and ground to the temperature blend door actuator motor through the actuator motor circuits to rotate the temperature blend door actuator. To reverse the temperature blend door actuator rotation, the HVAC module reverses the voltage and ground on the circuits.
The temperature blend door actuator feedback resistor is supplied a 5-volt reference voltage and ground from the HVAC module. The HVAC module measures the resistance on the temperature blend door actuator feedback circuit to determine the temperature blend door actuator position by the position of the actuator feedback resistor wiper arm.
During an actuator calibration cycle, the HVAC module drives the temperature blend door until the door reaches both internal stops in the HVAC case. If the temperature blend door is temporarily obstructed or binding during a calibration cycle, the HVAC module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC module commands the actuator to its end of travel, the airflow may not be the expected temperature.
- DTC 2-1 (Blend Feedback Circuit/Performance)- The module senses no changes in the feedback circuit when motor movement is commanded and no motor electrical DTCs are present. This indicates an open actuator motor, an open or shorted feedback circuit, an open feedback resistor reference voltage circuit, or an internal electrical or mechanical failure.
- DTC 2-2 (Blend Motor Driver Circuit/Performance)- The module senses lower than expected voltage on an actuator motor circuit when voltage is applied to drive the motor. This indicates a short to ground or the module senses greater than expected voltage on the actuator motor circuit when ground is applied to drive the motor, indicating a short to voltage.
- DTC 2-3 (Blend Actuator Calibration Performance)- The module senses the actuator has moved outside its travel limits during calibration. This indicates broken/disconnected linkage or door or an internal mechanical failure.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Temperature blend door actuator
- HVAC module
- Temperature blend door is binding or stuck
PINPOINT TEST M : TEMPERATURE CONTROL IS INOPERATIVE/DOES NOT OPERATE CORRECTLY
M1 CHECK THE HVAC MODULE FOR DTCs
NOTE: If HVAC DTC 4-4 is present, GO to Pinpoint Test D and diagnose that DTC first Pinpoint Test D: DTC 4-4.
- Ignition ON.
- CARRY OUT the HVAC module self-test.
- Check for HVAC DTCs retrieved during the self-test.
Are HVAC DTCs present?
Yes
For DTC 2-1, GO to M2.
For DTC 2-2, GO to M9.
For DTC 2-3, GO to M8.
No
GO to M7.
M2 CHECK THE ACTUATOR MOTOR AND CIRCUITS
- Ignition OFF.
- Disconnect: HVAC Module C228A.
- Measure the resistance between HVAC module C228A-17, circuit CH235 (BU), harness side and HVAC module C228A-19, circuit CH236 (WH), harness side.
Is the resistance less than 40 ohms?
Yes
GO to M4.
No
GO to M3.
M3 CHECK THE TEMPERATURE BLEND DOOR ACTUATOR
- Ignition OFF.
- Disconnect: Temperature Blend Door Actuator C2092.
- CARRY OUT the Temperature Blend Door Actuator component test Component Tests.
Did the temperature blend door actuator test OK?
Yes
REPAIR circuit CH235 (BU) or CH236 (WH) for an open or high resistance. REPEAT the self-test. TEST the system for normal operation.
No
GO to M13.
M4 CHECK THE POTENTIOMETER LOW- AND HIGH-SIDE RESISTANCE
- Measure the high-side resistance between HVAC module C228A-12, circuit CH232 (WH/BN), harness side and HVAC module C228A-11, circuit CH206 (YE/VT), harness side.
- Measure the low-side resistance between HVAC module C228A-2, circuit CH233 (VT/BN), harness side and HVAC module C228A-11, circuit CH206 (YE/VT), harness side.
Are the resistances between 215 and 4,375 ohms?
Yes
GO to M5.
No
CARRY OUT the Temperature Blend Door Actuator component test Component Tests. INSTALL a new defrost/panel/floor mode door actuator if necessary.
If the actuator tests OK and:
If the high-side resistance only is greater than 4,375 ohms, REPAIR circuit CH232 (WH/BN) for an open.
If the high-side resistance only is less than 215 ohms, REPAIR circuits CH206 (YE/VT) and CH232 (WH/BN) for a short together.
If the low-side resistance only is greater than 4,375 ohms, REPAIR circuit CH233 (VT/BN) for an open.
If thelow-side resistance only is less than 215 ohms, REPAIR circuits CH206 (YE/VT) and CH233 (VT/BN) for a short together.
If both thehigh-side and low-side resistance is greater than 4,375 ohms, REPAIR circuit CH206 (YE/VT) for an open.
Once the repair is complete, CALIBRATE the actuators. REFER to Calibrating the HVAC Actuators. TEST the system for normal operation.
M5 CHECK THE ACTUATOR FEEDBACK CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and HVAC module C228A-11, circuit CH206 (YE/VT), harness side.
Is any voltage present?
Yes
REPAIR circuit CH206 (YE/VT) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to M6.
M6 CHECK THE ACTUATOR FEEDBACK CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between ground and HVAC module C228A-11, circuit CH206 (YE/VT), harness side.
Are the resistances greater than 10,000 ohms?
Yes
GO to M7.
No
REPAIR circuit CH206 (YE/VT) or CH233 (VT/BN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
M7 CHECK THE TEMPERATURE BLEND DOOR ACTUATOR OPERATION
- Ignition OFF.
- Disconnect: HVAC Module C228A (If not previously disconnected).
- Measure the resistance between HVAC module C228A-2, circuit CH233 (VT/BN), harness side and HVAC module C228A-11, circuit CH206 (YE/VT), harness side.
- Connect a fused jumper wire between:
- HVAC module C228A-10, circuit SBP07 (WH/RD), harness side and HVAC module C228A-17, circuit CH235 (BU), harness side.
- HVAC module C228A-13, circuit GD115 (BK/GY), harness side and HVAC module C228A-19, circuit CH236 (WH), harness side.
- Remove the fused jumpers.
- Connect a fused jumper wire between:
- HVAC module C228A-13, circuit GD115 (BK/GY), harness side and HVAC module C228A-17, circuit CH235 (BU), harness side.
- HVAC module C228A-10, circuit SBP07 (WH/RD), harness side and HVAC module C228A-19, circuit CH236 (WH), harness side.
Does the resistance smoothly increase to approximately 3,500 ohms and/or decrease to approximately 290 ohms when the jumpers are connected?
Yes
GO to M14.
No
GO to M8.
M8 CHECK THE TEMPERATURE BLEND DOOR AND LINKAGE
- Disconnect: Temperature Blend Door Actuator C2092.
- REMOVE the temperature blend door actuator.
- INSPECT the temperature blend door and linkage for a broken, loose or binding condition.
Is any condition found during inspection?
Yes
REPAIR the temperature blend door or linkage REINSTALL the temperature blend door actuator. CALIBRATE the actuators. REFER to Calibrating the HVAC Actuators. TEST the system for normal operation.
No
GO to M13.
M9 CHECK THE ACTUATOR MOTOR DRIVE CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: HVAC Module C228A.
- Ignition ON.
- Measure the voltage between ground and:
- HVAC module C228A-17, circuit CH235 (BU), harness side.
- HVAC module C228A-19, circuit CH236 (WH), harness side.
Are any voltages present?
Yes
REPAIR circuit CH235 (BU) or CH236 (WH) for a short to voltage. TEST the system for normal operation.
No
GO to M10.
M10 CHECK THE ACTUATOR MOTOR DRIVE CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between ground and:
- HVAC module C228A-17, circuit CH235 (BU), harness side.
- HVAC module C228A-19, circuit CH236 (WH), harness side.
Are the resistances greater than 10,000 ohms?
Yes
GO to M11.
No
REPAIR circuit CH235 (BU) or CH236 (WH) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
M11 CHECK THE ACTUATOR MOTOR AND CIRCUIT RESISTANCE
- Measure the resistance between HVAC module C228A-17, circuit CH235 (BU), harness side and HVAC module C228A-19, circuit CH236 (WH), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to M14.
No
GO to M12.
M12 CHECK THE ACTUATOR MOTOR CIRCUITS FOR A SHORT TOGETHER
- Disconnect: Temperature Blend Door Actuator C2092.
- Measure the resistance between HVAC module C228A-17, circuit CH235 (BU), harness side and HVAC module C228A-19, circuit CH236 (WH), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to M13.
No
REPAIR circuits CH235 (BU) and CH236 (WH) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
M13 CHECK THE ACTUATOR CONNECTION
- Disconnect the temperature blend door actuator connector.
- Inspect the temperature blend door actuator connector for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- REINSTALL the temperature blend door actuator, If removed.
- Connect and correctly seat the temperature blend door actuator connector.
- CALIBRATE the actuators. REFER to Calibrating the HVAC Actuators.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new temperature blend door actuator. CALIBRATE the actuators. REFER to Calibrating the HVAC Actuators. 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.
M14 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 now operating correctly at this time. The concern may have been caused by a foreign object in the HVAC case or temporary binding that restricted actuator door travel. CHECK any actuator external linkage. If condition recurs, INSPECT actuator linkage and door for binding and CHECK HVAC case for foreign objects.