Pinpoint Test I: One Or More Stoplamps Are Inoperative
Stoplamps
Pinpoint Tests
Pinpoint Test I: One Or More Stoplamps Are Inoperative
Refer to Wiring Diagram Set 90, Turn Signal/Stop/Hazard Lamps for schematic and connector information. Diagrams By Number
Normal Operation
When the brake pedal is applied, the stoplamp switch closes and routes voltage to the high mounted stoplamp and the multifunction switch. The multifunction switch then routes the voltage to the LH and RH stoplamps.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- High mounted stoplamp
- Multifunction switch
PINPOINT TEST I: ONE OR MORE STOPLAMPS ARE INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery, Mounting and Cables Battery Disconnect.
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I1 CHECK THE HIGH MOUNTED STOPLAMP OPERATION
- Ignition OFF.
- Apply the brake pedal.
- Does the high mounted stoplamp illuminate?
Yes
GO to I4.
No
GO to I2.
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I2 CHECK FOR VOLTAGE TO THE HIGH MOUNTED STOPLAMP
- Disconnect: High Mounted Stoplamp C475.
- While applying the brake pedal, measure the voltage between the high mounted stoplamp C475-1, circuit 10 (LG/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to I3.
No
REPAIR circuit 10 (LG/RD) for an open. TEST the system for normal operation.
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I3 CHECK FOR VOLTAGE TO THE HIGH MOUNTED STOPLAMP USING THE CONNECTOR GROUND
- While applying the brake pedal, measure the voltage between the high mounted stoplamp C475-1, circuit 10 (LG/RD), harness side and the high mounted stoplamp C475-2, circuit 57 (BK), harness side.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new high mounted stoplamp. REFER to High Mounted Stoplamp Service and Repair. TEST the system for normal operation.
No
REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
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I4 DETERMINE IF THE LH AND RH REAR STOPLAMPS ARE INOPERATIVE
NOTE: Make sure the multifunction switch is in the NEUTRAL position.
- Apply the brake pedal.
- Are both the LH and RH rear stoplamps inoperative?
Yes
GO to I5.
No
GO to I7.
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I5 CHECK FOR VOLTAGE TO THE MULTIFUNCTION SWITCH
- Disconnect: Multifunction Switch C202a.
- While applying the brake pedal, measure the voltage between the multifunction switch C202a-4, circuit 10 (LG/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to I6.
No
REPAIR circuit 10 (LG/RD) for an open. TEST the system for normal operation.
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I6 BYPASS THE MULTIFUNCTION SWITCH (BOTH REAR STOPLAMPS)
- Connect a fused jumper wire between the multifunction switch C202a-4, circuit 10 (LG/RD), harness side and the multifunction switch C202a-5, circuit 5 (OG/LB), harness side.
- Apply the brake pedal while observing the RH rear stoplamps.
- Do the RH rear stoplamps illuminate?
Yes
REMOVE the jumper wire. INSTALL a new multifunction switch. REFER to Steering Column Switches Steering Column Multifunction Switch. TEST the system for normal operation.
No
REMOVE the jumper wire. REPAIR circuit 57 (BK) for an open to the rear lamps. TEST the system for normal operation.
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I7 CHECK FOR VOLTAGE TO THE REAR STOPLAMP
- Disconnect: Inoperative Stoplamp.
- Measure the voltage between the inoperative stoplamp, harness side and ground as follows:
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
No
GO to I8.
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I8 CHECK THE MULTIFUNCTION SWITCH
- Disconnect: Multifunction Switch.
- Carry out the multifunction switch component test.
Refer to Headlamp Dimmer Switch, Turn Signal Switch, Windshield Washer Switch, or Wiper Switch for component testing.
- Is the multifunction switch OK?
Yes
REPAIR circuit 9 (LG/OG) (LH stoplamp) or circuit 5 (OG/LB) (RH stoplamp) as necessary. TEST the system for normal operation.
No
INSTALL a new multifunction switch. REFER to Steering Column Switches Steering Column Multifunction Switch. TEST the system for normal operation.
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