Pinpoint Test I: One Or More Stoplamps Are Inoperative
Stoplamps
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 routes voltage to the multifunction switch and the circuit filter. The multifunction switch then routes the voltage to the LH and RH rear lamps, and the circuit filter routes the voltage to the high mounted stoplamp.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Circuit filter
- 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.
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I1 VERIFY THE INOPERATIVE STOPLAMP(S)
- Ignition OFF.
- Apply the brake pedal.
- Does the high mounted stoplamp illuminate?
Yes
GO to I6.
No
GO to I2.
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I2 CHECK FOR VOLTAGE TO THE HIGH MOUNTED STOPLAMP
- Disconnect: High Mounted Stoplamp C904.
- While applying the brake pedal, measure the voltage between the high mounted stoplamp C904-1, circuit 511 (LG), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to I3.
No
GO to I4 .
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I3 CHECK THE HIGH MOUNTED STOPLAMP GROUND CIRCUIT FOR AN OPEN
- Measure the voltage between the high mounted stoplamp C904-1, circuit 511 (LG), harness side and the high mounted stoplamp C904-2, circuit 57 (BK), harness side and ground.
- 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 CHECK FOR VOLTAGE TO THE CIRCUIT FILTER
- Disconnect: Circuit Filter C3148.
- While applying the brake pedal, measure the voltage between the circuit filter C3148-1, circuit 10 (LG/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to I5.
No
REPAIR circuit 10 (LG/RD) for an open. TEST the system for normal operation.
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I5 CHECK THE HIGH MOUNTED STOPLAMP VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Measure the resistance between the high mounted stoplamp C904-1, circuit 511 (LG), harness side and the circuit filter C3148-3, circuit 511 (LG), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new circuit filter. TEST the system for normal operation.
No
REPAIR circuit 511 (LG) for an open. TEST the system for normal operation.
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I6 DETERMINE IF BOTH 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 I7.
No
GO to I9.
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I7 CHECK FOR VOLTAGE TO THE MULTIFUNCTION SWITCH
- Disconnect: Multifunction Switch C202c.
- While applying the brake pedal, measure the voltage between the multifunction switch C202c-4, circuit 10 (LG/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to I8.
No
REPAIR circuit 10 (LG/RD) for an open. TEST the system for normal operation.
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I8 BYPASS THE MULTIFUNCTION SWITCH
- Connect a fused jumper wire between the multifunction switch C202c-4, circuit 10 (LG/RD), harness side and the multifunction switch C202c-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. TEST the system for normal operation.
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I9 CHECK FOR VOLTAGE TO THE REAR STOPLAMP
- Disconnect: Inoperative Stoplamp.
- While applying the brake pedal, 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 I10.
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I10 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) for an open 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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