Pinpoint Test C: The TCS Or Tow/Haul Switch Is Not Operating Correctly

External Controls

Pinpoint Tests

PINPOINT TEST C: THE TCS OR TOW/HAUL SWITCH IS NOT OPERATING CORRECTLY

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C1 CHECK SJB FUSE 35 (10A)


- Ignition OFF.
- Check fuse: Smart Junction Box (SJB) 35 (10A).
- Is the resistance less than 5 ohms?

Yes
REINSTALL the fuse. GO to C5 .

No
INSTALL a new fuse. TEST the system for normal operation. If the fuse fails again, GO to C2 .

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C2 CHECK SJB FOR AN INTERNAL SHORT


- Disconnect: SJB C2280B.
- Inspect for damaged or pushed-out terminals, corrosion or loose wires. Repair as necessary.
- Install a new fuse.
- Did the fuse fail?

Yes
INSTALL a new SJB. REFER to Body Control Systems. RECONNECT all components. TEST the system for normal operation.

No
GO to C3.

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C3 CHECK CIRCUIT CBP35 (YE/GY) FOR A SHORT TO GROUND


- Disconnect: Transmission Control Switch (TCS) or Tow/Haul Switch C2255.
- Disconnect: 4X4 Control Module C281A.
- Disconnect: Traction Control Switch C280.
- Inspect for damaged or pushed-out terminals, corrosion or loose wires. Repair as necessary.
- Measure the resistance between TCS or tow/haul switch C2255-1, circuit CBP35 (YE/GY), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to C4.

No
REPAIR circuit CBP35 (YE/GY). RECONNECT all components. TEST the system for normal operation.

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C4 CHECK CIRCUIT CAT15 (BN/YE) FOR A SHORT TO GROUND


- Disconnect: PCM C175B.
- Disconnect: Transmission Control Module (TCM) C1750.
- For gasoline engine vehicles, measure the resistance between PCM C175B-27, circuit CAT15 (BN/YE), harness side and ground.




- For diesel engine vehicles, measure the resistance between TCM C1750-53, circuit CAT15 (BN/YE), harness side and ground.




- Is the resistance greater than 10,000 ohms for all circuits?

Yes
INSTALL a new PCM or TCM. RECONNECT all components. TEST the system for normal operation.

No
REPAIR circuit CAT15 (BN/YE) . RECONNECT all components. TEST the system for normal operation.

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C5 CHECK SJB FOR AN INTERNAL OPEN


- Disconnect: SJB C2280B.
- Inspect for damaged or pushed-out terminals, corrosion or loose wires. Repair as necessary.
- Ignition ON.
- Measure the voltage at SJB C2280B-9, component side.




- Is the voltage greater than 10 volts?

Yes
GO to C6.

No
INSTALL a new SJB. REFER to Body Control Systems. RECONNECT all components. TEST the system for normal operation.

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C6 CHECK CIRCUIT CBP35 (YE/GY) FOR AN OPEN


- Ignition OFF.
- Disconnect: TCS or Tow/Haul Switch C2255.
- Disconnect: 4X4 Control Module C281A.
- Disconnect: Traction Control Switch C280.
- Measure the resistance between TCS or tow/haul switch C2255-1, circuit CBP35 (YE/GY), harness side and SJB C2280-9, circuit CBP35 (YE/GY), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to C7.

No
SERVICE circuit CBP35 (YE/GY) for an open. RECONNECT all components. TEST the system for normal operation.

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C7 CHECK CIRCUIT CAT15 (BN/YE) FOR AN OPEN


- Disconnect: PCM C175B.
- Disconnect: TCM C1750.
- For gasoline engine vehicles, measure the resistance between TCS or tow/haul switch C2255-2, circuit CAT15 (BN/YE), harness side and PCM C175B-27, circuit CAT15 (BN/YE), harness side.




- For diesel engine vehicles, measure the resistance between TCS or tow/haul switch C2255-2, circuit CAT15 (BN/YE), harness side and TCM C1750-53, circuit CAT15 (BN/YE), harness side.




- Is the resistance less than 5 ohms for all circuits?

Yes
GO to C8.

No
SERVICE circuit CAT15 (BN/YE) for an open. RECONNECT all components. TEST the system for normal operation.

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C8 CHECK TCS OR TOW/HAUL SWITCH


- Measure the resistance between TCS or tow/haul switch C2255-1 and TCS or tow/haul switch C2255-2, 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
GO to C9.

No
INSTALL a new TCS or tow/haul switch. RECONNECT all components. TEST the system for normal operation.

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C9 CHECK THE PCM OR TCM


- Connect: SJB C2280B.
- Connect: TCS or Tow/Haul Switch C2255.
- Ignition ON.
- For gasoline engine vehicles, measure the voltage at PCM C175B-27, circuit CAT15 (BN/YE), harness side, while pressing and releasing the switch.




- For diesel engine vehicles, measure the voltage at TCM C1750-53, circuit CAT15 (BN/YE), harness side, while pressing and releasing the switch.




- Is the voltage greater than 10 volts with the switch pressed, and less than 5 volts with the switch released?

Yes
INSTALL a new PCM or TCM. RECONNECT all components. TEST the system for normal operation.

No
SERVICE circuit CAT15 (BN/YE) for an open. RECONNECT all components. TEST the system for normal operation.

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