Pinpoint Test Y: The Trailer Electric Brakes Are Inoperative/Always Applied
Trailer Lamps
Pinpoint Tests
Pinpoint Test Y: The Trailer Electric Brakes Are Inoperative/Always Applied
Refer to Wiring Diagram Set 95, Trailer/Camper Adapter for schematic and connector information. Diagrams By Number
Normal Operation
The trailer electric brake controller is provided voltage at all times by the Battery Junction Box (BJB) fuse 18 (30A) through circuit SBB18 (YE/RD). Ground for the trailer electric brake controller is provided through circuit GD116 (BK/VT). The trailer electric brake controller receives voltage from the stoplamp switch through circuit CCB08 (VT/WH) when the brake pedal is applied. When a brake application is detected from the stoplamp switch, the trailer electric brake controller sends voltage to the trailer tow connector through circuit CAT19 (BU).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Trailer tow connector
- Trailer electric brake controller
- Trailer
PINPOINT TEST Y: THE TRAILER ELECTRIC BRAKES ARE INOPERATIVE/ALWAYS APPLIED
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Before beginning diagnostics, visually inspect the trailer tow connector for signs of corrosion or damage. Repair or install a new trailer tow connector as required.
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Y1 CHECK THE TRAILER ELECTRIC BRAKE CONTROLLER FOR A SHORTED OUTPUT
- Ignition ON.
- Measure the voltage between the trailer tow connector electric brake control supply pin, circuit CAT19 (BU), component side and ground.
- Is any voltage present?
Yes
GO to Y2.
No
GO to Y3.
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Y2 CHECK CIRCUIT CAT19 (BU) FOR A SHORT TO VOLTAGE
- Disconnect: Trailer Electric Brake Controller C2142.
- Measure the voltage between the trailer tow connector electric brake control supply pin, circuit CAT19 (BU), component side and ground.
- Is any voltage present?
Yes
REPAIR circuit CAT19 (BU) for a short to voltage. TEST the system for normal operation.
No
INSTALL a new trailer electric brake controller. TEST the system for normal operation.
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Y3 CHECK THE TRAILER ELECTRIC BRAKE CONTROLLER OUTPUT
- Set the gain on the trailer electric brake controller to the maximum setting.
- While applying the brake pedal, measure the voltage between the trailer tow connector electric brake control supply pin, circuit CAT19 (BU), component side and ground.
- Is the voltage greater than 10 volts?
Yes
The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.
No
GO to Y4.
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Y4 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR
- Disconnect: Trailer Tow C4099.
- NOTE: Make sure the gain is still set to the maximum setting.
- While applying the brake pedal, measure the voltage between the trailer tow C4099-3, circuit CAT19 (BU), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new trailer tow connector. TEST the system for normal operation.
No
GO to Y5.
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Y5 CHECK FOR VOLTAGE TO THE TRAILER ELECTRIC BRAKE CONTROLLER
- Disconnect: Trailer Electric Brake Controller C2142.
- Measure the voltage between the trailer electric brake controller C2142-8, circuit SBB18 (YE/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Y6.
No
VERIFY the BJB fuse 18 (30A) is OK. If OK, REPAIR circuit SBB18 (YE/RD) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
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Y6 CHECK THE STOPLAMP SWITCH INPUT TO THE TRAILER ELECTRIC BRAKE CONTROLLER
- While applying the brake pedal, measure the voltage between the trailer electric brake controller C2142-10, circuit CCB08 (VT/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Y7.
No
REPAIR circuit CCB08 (VT/WH) for an open. TEST the system for normal operation.
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Y7 CHECK FOR VOLTAGE TO THE TRAILER ELECTRIC BRAKE CONTROLLER USING THE GROUND PIN
- Measure the voltage between the trailer electric brake controller C2142-8, circuit SBB18 (YE/RD), harness side and the trailer electric brake controller C2142-11, circuit GD116 (BK/VT), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to Y8.
No
REPAIR circuit GD116 (BK/VT) for an open. TEST the system for normal operation.
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Y8 CHECK THE TRAILER ELECTRIC BRAKE CONTROLLER OUTPUT CIRCUIT FOR A SHORT TO GROUND
- Measure the resistance between the trailer electric brake controller C2142-14, circuit CAT19 (BU), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to Y9.
No
REPAIR circuit CAT19 (BU) for a short to ground. TEST the system for normal operation.
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Y9 CHECK THE TRAILER ELECTRIC BRAKE CONTROLLER OUTPUT CIRCUIT FOR AN OPEN
- Connect a fused jumper wire between the trailer electric brake controller C2142-8, circuit SBB18 (YE/RD), harness side and the trailer electric brake controller C2142-14, circuit CAT19 (BU), harness side.
- Measure the voltage between the trailer tow C4099-3, circuit CAT19 (BU), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new trailer electric brake controller. TEST the system for normal operation.
No
REPAIR circuit CAT19 (BU) for an open. TEST the system for normal operation.
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