Pinpoint Test M: DTC C2809
Anti-Lock Control
Pinpoint Tests
Pinpoint Test M: DTC C2809
Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number
Normal Operation
Hill Descent Control(TM) can be activated at speeds below 40 mph by momentarily pressing the Hill Descent Control(TM) switch. However, at speeds above 32 km/h (20 mph), Hill Descent Control(TM) will not set or maintain speeds.
Fused ignition voltage is supplied to the Hill Descent Control(TM) switch from Smart Junction Box (SJB) fuse 34 (5A) along circuit CBP34 (VT/BN). When the Hill Descent Control(TM) switch is pressed, a circuit inside of the switch is closed, which provides a 12-volt signal to the PCM along circuit CCF12 (BU/GY). The PCM then broadcasts a message to the Instrument Cluster (IC) and ABS module over the High Speed Controller Area Network (HS-CAN) bus that the Hill Descent Control(TM) switch is being pressed. The PCM will also ground circuit CCF02 (GN/WH) which will illuminate the indicator in the switch.
DTC C2809 can be set by manually pressing and holding the Hill Descent Control(TM) switch for more than 30 seconds.
- DTC C2809 (Hill Descent Control Switch Stuck) - If the ABS module receives the HILL_DESC_SW message from the HS-CAN bus for greater than 30 seconds, DTC C2809 will set.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Hill Descent Control(TM) switch
- ABS module
PINPOINT TEST M: DTC C2809
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.
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M1 CHECK FOR DTCs
- Connect the scan tool.
- Ignition ON.
- Check for any ABS module, PCM, or communication DTCs.
- Are any DTCs present?
Yes
For ABS module DTCs, REFER to the ABS Module DTC Chart. [1][2]Diagnostic Trouble Code Descriptions
For PCM DTCs, REFER to the Computers and Control Systems.
For any communication DTCs, refer to Information Bus.
No
GO to M2
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M2 VISUALLY INSPECT THE HILL DESCENT CONTROL(TM) SWITCH
- Inspect the Hill Descent Control(TM) switch for damage.
- Verify that the Hill Descent Control(TM) switch does not stick.
- Is the Hill Descent Control(TM) switch damaged or sticking?
Yes
INSTALL a new Hill Descent Control(TM) switch by removing the auxiliary switch assembly. REFER to the exploded view in Instrument Cluster / Carrier &/or Interior Moulding / Trim. PRESS the tab on each side of the switch to remove it from the bezel. After replacing the switch, CLEAR the DTCs and REPEAT the self-test. TEST the system for normal operation.
No
GO to M3.
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M3 ISOLATE THE HILL DESCENT CONTROL(TM) SWITCH
- Ignition OFF.
- Disconnect: Hill Descent Control(TM) switch C3394 .
- Measure the resistance between Hill Descent Control(TM) switch pin-1 and pin-6, component side, while pressing and releasing the switch.
- Is the resistance less than 5 ohms with the switch pressed and greater than 10,000 ohms with the switch released?
Yes
If DTC C2809 was recorded, GO to M4. For all other conditions, GO to M5.
No
INSTALL a new Hill Descent Control(TM) switch by removing the auxiliary switch assembly. REFER to the exploded view in Instrument Cluster / Carrier &/or Interior Moulding / Trim. PRESS the tab on each side of the switch to remove it from the bezel. After replacing the switch, CLEAR the DTCs and REPEAT the self-test. TEST the system for normal operation.
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M4 CHECK THE HILL DESCENT CONTROL(TM) SWITCH SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: Hill Descent Control(TM) switch C3394 .
- Disconnect: PCM C175B (5.4L vehicles) .
- Disconnect: PCM C1381B (6.2L vehicles) .
- Ignition ON.
- Measure the voltage between Hill Descent Control(TM) switch C3394-1, circuit CCF12 (BU/GY), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit CCF12 (BU/GY). CLEAR the DTCs. REPEAT the self-test.
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.
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M5 CHECK THE HILL DESCENT CONTROL(TM) SWITCH SIGNAL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Hill Descent Control(TM) Switch C3394 .
- Disconnect: PCM C175B (5.4L vehicles) .
- Disconnect: PCM C1381B (6.2L vehicles) .
- For 5.4L vehicles: Measure the resistance between Hill Descent Control(TM) switch C3394-1, circuit CCF12 (BU/GY), harness side and PCM C175B-3.
- For 6.2L vehicles: Measure the resistance between Hill Descent Control(TM) switch C3394-1, circuit CCF12 (BU/GY), harness side and PCM C1381B-22, circuit CCF12 (BU/GY), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to M6.
No
REPAIR circuit CCF12 (BU/GY). TEST the system for normal operation.
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M6 CHECK THE HILL DESCENT CONTROL(TM) SWITCH VOLTAGE SUPPLY CIRCUIT FOR VOLTAGE
- Ignition ON.
- Measure the voltage between Hill Descent Control(TM) switch C3394-6, circuit CBP34 (VT/BN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to M7.
No
VERIFY SJB fuse 34 (5A) is OK. If OK, REPAIR circuit CBP34 (VT/BN). If not OK, REFER to the Wiring Diagrams to identify the cause of the circuit short. TEST the circuit for normal operation. Diagrams By Number
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M7 CHECK FOR CORRECT PCM OPERATION
- Check PCM connector C175B (5.4L vehicles) or PCM C1381B (6.2L vehicles) for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect the PCM connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new PCM. REFER to Computers and Control Systems. 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.
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