Pinpoint Test L: Temperature Control Is Inoperative/Does Not Operate Correctly
Climate Control System
Pinpoint Tests
Pinpoint Test L: Temperature Control is Inoperative/Does Not Operate Correctly
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, to rotate the mode door actuator clockwise, the HVAC module supplies voltage to the BLEND door actuator motor through circuit 1376 (BK/LB), and supplies ground through circuit 1375 (PK/YE). To rotate the mode door actuator counterclockwise, the HVAC module reverses the voltage and ground circuits.
The blend door actuator feedback resistors are supplied a ground from the HVAC module by circuit 438 (RD/WH) and a 5-volt reference voltage on circuit 436 (RD/LG). The HVAC module reads the voltage on circuit 437 (YE/LG) to determine the blend door actuator position by the position of the actuator feedback resistor wiper arm.
This pinpoint test is intended to diagnose the following:
- An open, short to voltage, ground or together in door actuator open, close, return, reference or feedback circuits
- Blend, air inlet, defrost and floor/panel mode door actuator motor
- HVAC module
- Manual climate control module
- Stuck or bound linkage or door
PINPOINT TEST L: TEMPERATURE CONTROL IS INOPERATIVE/DOES NOT OPERATE CORRECTLY
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L1 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE
NOTICE: Use the correct size flex probe from the Flex Probe Kit for all test connections. The use of the correct size flex probe is critical to avoid damage to the connector terminals.
NOTE: Check all electrical connectors for proper seating before disconnecting. If incorrectly seated, reseat and lock the connector. Test the system operation. If the condition remains, continue with this test.
- Disconnect: HVAC Module C294a.
- Measure the resistance between HVAC module C294a-5, circuit 436 (RD/LG) and HVAC module C294a-15, circuit 438 (RD/WH).
- Is the resistance greater than 500 ohms?
Yes
GO to L2.
No
REPAIR circuits 436 (RD/LG) and 438 (RD/WH) for a short together. TEST the system for normal operation.
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L2 CHECK THE POTENTIOMETER LOW- AND HIGH-SIDE RESISTANCE
- Measure the low-side resistance between HVAC module C294a-15, circuit 438 (RD/WH) and HVAC module C294a-18, circuit 437 (YE/LG).
- Measure the high-side resistance between HVAC module C294a-5, circuit 436 (RD/LG) and HVAC module C294a-18, circuit 437 (YE/LG).
- Is the resistance between 225 and 11,275 ohms?
Yes
GO to L3.
No
CARRY OUT the Temperature Blend Door Actuator Component Test. If the actuator tests OK and: Blend Mode Door Actuator
If the low-side resistance only is greater than 11,275 ohms, REPAIR circuit 438 (RD/WH) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
If the low-side resistance only is less than 225 ohms, REPAIR circuits 437 (YE/LG) and 438 (RD/WH) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
If the high-side resistance only is greater than 11,275 ohms, REPAIR circuit 436 (RD/LG) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
If thehigh-side resistance only is less than 225 ohms, REPAIR circuits 437 (YE/LG) and 436 (RD/LG) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
If thehigh-side and low-side resistance is greater than 11,275 ohms, REPAIR circuit 437 (YE/LG) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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L3 CHECK CIRCUITS 436 (RD/LG) AND 437 (YE/LG) FOR A SHORT TO GROUND
- Disconnect: Blend Door Actuator C289.
- Measure the resistance between ground and the following:
- HVAC module C294a-5, circuit 436 (RD/LG).
- HVAC module C294a-18, circuit 437 (YE/LG).
- Is the resistance greater than 10,000 ohms?
Yes
GO to L4.
No
REPAIR circuit(s) for a short to ground. TEST the system for normal operation.
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L4 CHECK CIRCUITS 438 (RD/WH) AND 437 (YE/LG) FOR A SHORT TO POWER
- Ignition ON.
- Measure the voltage between ground and the following:
- HVAC module C294a-15, circuit 438 (RD/WH).
- HVAC module C294a-18, circuit 437 (YE/LG).
- Is any voltage present?
Yes
REPAIR circuit(s) for a short to power. TEST the system for normal operation.
No
GO to L5.
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L5 CHECK THE DOOR ACTUATOR OPERATION
NOTE: If a jumper fuse opens while carrying out this test step, repair the circuit(s) for a short.
- Measure the low-side resistance between HVAC module C294a-15, circuit 438 (RD/WH) and HVAC module C294a-18, circuit 437 (YE/LG).
- For no more than 3 seconds, connect a fused jumper wire between:
- HVAC module C294a-26, circuit 1566 (RD/YE) and HVAC module C294a-7, circuit 1376 (BK/LB).
- HVAC module C294a-1, circuit 1205 (BK) and HVAC module C294a-6, circuit 1375 (PK/YE).
- Remove the fused jumpers.
- For no more than 3 seconds, connect a fused jumper wire between:
- HVAC module C294a-1, circuit 1205 (BK) and HVAC module C294a-7, circuit 1376 (BK/LB).
- HVAC module C294a-26, circuit 1566 (RD/YE) and HVAC module C294a-6, circuit 1375 (PK/YE).
- Does the resistance smoothly increase and/or decrease when the jumpers are connected?
Yes
INSPECT for broken door and linkage. REPAIR as necessary. If no condition is found, GO to L7.
No
GO to L6.
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L6 CHECK THE ACTUATOR MOTOR DRIVE CIRCUITS FOR AN OPEN
NOTE: Due to limited connector accessibility, before carrying out this test step, visually inspect the wiring between the HVAC module and actuator for opens or shorts. If no damage is visually evident, proceed with the test.
- Ignition OFF.
- Disconnect: Blend Door Actuator C289.
- Measure the resistance between HVAC module C294a-7, circuit 1376 (BK/LB) and blend door actuator C289-6, circuit 1376 (BK/LB).
- Measure the resistance between HVAC module C294a-6, circuit 1375 (PK/YE) and blend door actuator C289-1, circuit 1375 (PK/YE).
- Is the resistance less than 5 ohms?
Yes
INSPECT for binding or broken linkage. REPAIR as necessary. If no condition is found, INSTALL a new door actuator. TEST the system for normal operation.
No
REPAIR the circuit(s) for an open. TEST the system for normal operation.
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L7 MODULE ACTUATOR POSITION CALIBRATION
NOTE: The purpose of the module actuator position calibration is to allow the HVAC module to reinitialize and calibrate the actuator stop points. To carry out the calibration, follow the steps below.
- Ignition OFF.
- Inspect the module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect: EMTC Module C294a.
- Ignition ON.
- Select any position except OFF.
- NOTE: The HVAC module will now initialize and calibrate the actuators. Calibration of the actuators will take approximately 30 seconds.
- Operate the system.
- Does the concern return?
Yes
INSTALL a new HVAC module. TEST the system for normal operation.
No
The system is now operating correctly. 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.
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