Pinpoint Test K: the Air Inlet Door Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test K: The Air Inlet Door is Inoperative
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the air inlet door actuator motor is supplied voltage or ground on circuit 1069 (OG/LB), depending on desired actuator rotation, by the HVAC module. The HVAC module then supplies the appropriate voltage or ground to the other side of the actuator motor on circuit 660 (YE/LG).
The air inlet door actuator feedback resistor is supplied a ground from the HVAC module through circuit 438 (RD/WH) and a 5-volt reference voltage on circuit 436 (RD/LG). The HVAC module reads the voltage on the air inlet door actuator feedback circuit 435 (YE/LB) to determine the air inlet door actuator position by the position of the actuator feedback resistor wiper arm.
- DTC B1242 Air Flow Recirculation Door Driver Circuit Failure - The module senses no change in actuator feedback voltage when the actuator motor has been energized.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Air inlet door actuator motor
- HVAC module
- Stuck or bound linkage or door
PINPOINT TEST K: THE AIR INLET DOOR IS INOPERATIVE
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K1 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE
- Ignition OFF.
- Disconnect: HVAC Module C228a.
- Disconnect: HVAC Module C228b.
- Measure the resistance between HVAC module C228b-8, circuit 436 (RD/LG), harness side and HVAC module C228a-20, circuit 438 (RD/WH), harness side.
- Is the resistance greater than 500 ohms?
Yes
GO to K2.
No
CARRY OUT the Air Inlet Door Actuator Component Test. If the actuator tests OK, REPAIR circuits 436 (RD/LG) and 438 (RD/WH) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. Air Inlet Door Actuator
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K2 CHECK POTENTIOMETER LOW- AND HIGH-SIDE RESISTANCE
- Measure the low-side resistance between HVAC module C228a-20, circuit 438 (RD/WH), harness side and HVAC module C228b-3, circuit 435 (YE/LB), harness side.
- Measure the high-side resistance between HVAC module C228b-8, circuit 436 (RD/LG), harness side and HVAC module C228b-3, circuit 435 (YE/LB), harness side.
- Is the resistance between 250 and 5,500 ohms?
Yes
GO to K3.
No
If the low-side resistance only is greater than 5,500 ohms, CARRY OUT the Air Inlet Door Actuator Component Test. If the actuator tests OK, REPAIR circuit 438 (RD/WH) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. Air Inlet Door Actuator
If the low-side resistance only is less than 250 ohms, CARRY OUT the Air Inlet Door Actuator Component Test. If the actuator tests OK, REPAIR circuits 435 (YE/LB) and 438 (RD/WH) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. Air Inlet Door Actuator
If the high-side resistance only is greater than 5,500 ohms, CARRY OUT the Air Inlet Door Actuator Component Test. If the actuator tests OK, REPAIR circuit 436 (RD/LG) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. Air Inlet Door Actuator
If thehigh-side resistance only is less than 250 ohms, CARRY OUT the Air Inlet Door Actuator Component Test. If the actuator tests OK, REPAIR circuits 435 (YE/LB) and 436 (RD/LG) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. Air Inlet Door Actuator
If thehigh-side and low-side resistance is greater than 5,500 ohms, CARRY OUT the Air Inlet Door Actuator Component Test. If the actuator tests OK, REPAIR circuit 435 (YE/LB) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. Air Inlet Door Actuator
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K3 CHECK CIRCUITS 435 (YE/LB) AND 436 (RD/LG) FOR A SHORT TO GROUND
- Measure the resistance between ground and:
- HVAC module C228b-3, circuit 435 (YE/LB), harness side.
- HVAC module C228b-8, circuit 436 (RD/LG), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to K4.
No
REPAIR circuit 435 (YE/LB) or 436 (RD/LG) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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K4 CHECK CIRCUITS 435 (YE/LB) AND 438 (RD/WH) FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and:
- HVAC module C228b-3, circuit 435 (YE/LB), harness side.
- HVAC module C228a-20, circuit 438 (RD/WH), harness side.
- Is any voltage present?
Yes
GO to K5.
No
REPAIR circuit 435 (YE/LB) or 436 (RD/LG) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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K5 CHECK THE RECIRC DOOR ACTUATOR OPERATION
NOTE: If a jumper fuse opens while carrying out this test step, repair the circuit(s) for a short.
- Measure the resistance between HVAC module C228a-20, circuit 438 (RD/WH), harness side and HVAC module C228b-3, circuit 435 (YE/LB), harness side.
- Connect a fused jumper wire between:
- HVAC module C228a-9, circuit 1069 (OG/LB), harness side and HVAC module C228b-11, circuit 1566 (RD/YE), harness side.
- HVAC module C228a-10, circuit 660 (YE/LG), harness side and HVAC module C228a-2, circuit 57 (BK), harness side.
- Remove the fused jumpers.
- Connect a fused jumper wire between:
- HVAC module C228a-10, circuit 660 (YE/LG), harness side and HVAC module C228b-11, circuit 1566 (RD/YE), harness side.
- HVAC module C228a-9, circuit 1069 (OG/LB), harness side and HVAC module C228a-2, circuit 57 (BK), harness side.
- 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 K7.
No
GO to K6.
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K6 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: Air Inlet Door Actuator C289.
- Measure the resistance between HVAC module C228a-10, circuit 660 (YE/LG), harness side and the recirc door actuator C289-1, circuit 660 (YE/LG), harness side.
- Measure the resistance between HVAC module C228a-9, circuit 1069 (OG/LB), harness side and the recirc door actuator C289-6, circuit 1069 (OG/LB), harness side.
- 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. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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K7 CHECK HVAC MODULE CONNECTION
- Carry out the HVAC Module Cold Boot Process. HVAC Module Cold Boot Process
- Carry out the HVAC Module On-Demand Self Test. HVAC Module Self-Test
- Operate the system.
- Does the concern return?
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. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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