Pinpoint Test A: Both High Beams Are Inoperative
Headlamps
Pinpoint Tests
Pinpoint Test A: Both High Beams Are Inoperative
Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 140, Customer Access for schematic and connector information. Diagrams By Number
Normal Operation
The Smart Junction Box (SJB) sends a reference signal to the multifunction switch through circuit CLF17 (WH/OG). When the headlamp switch is in the HEADLAMPS ON position and the multifunction switch is placed in the HIGH BEAM position, the signal is routed to ground through circuit GD114 (BK/BU), indicating a high beam request. The SJB then energizes the high beam relay (integrated into the SJB) which supplies voltage to the headlamps through circuit CLF08 (YE/VT).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Multifunction switch
- Body builder equipment
- SJB
PINPOINT TEST A: BOTH HIGH BEAMS 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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A1 CHECK THE HIGH BEAM INDICATOR
- Ignition ON.
- Place the headlamp switch in the HEADLAMPS ON position.
- Place the multifunction switch in the HIGH BEAM position.
- Does the high beam indicator illuminate?
Yes
GO to A5.
No
GO to A2.
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A2 CHECK FOR A VOLTAGE REFERENCE SIGNAL TO THE MULTIFUNCTION SWITCH
- Place the headlamp switch in the OFF position.
- Ignition OFF.
- Disconnect: Multifunction Switch C202b.
- Measure the voltage between the multifunction switch C202b-9, circuit CLF17 (WH/OG), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to A3.
No
GO to A4.
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A3 BYPASS THE MULTIFUNCTION SWITCH
- Connect a fused jumper wire between the multifunction switch C202b-9, circuit CLF17 (WH/OG), harness side and the multifunction switch C202b-10, circuit GD114 (BK/BU), harness side.
- Place the headlamp switch in the HEADLAMPS ON position.
- Do the high beams illuminate?
Yes
REMOVE the jumper wire. INSTALL a new multifunction switch. TEST the system for normal operation.
No
REMOVE the jumper wire. REPAIR circuit GD114 (BK/BU) for an open.
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A4 CHECK THE HIGH BEAM REQUEST CIRCUIT FOR AN OPEN
- Disconnect: SJB C2280b.
- Measure the resistance between the multifunction switch C202b-9, circuit CLF17 (WH/OG), harness side and the SJB C2280b-27, circuit CLF17 (WH/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to A7.
No
REPAIR circuit CLF17 (WH/OG) for an open. TEST the system for normal operation.
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A5 CHECK THE HIGH BEAM OUTPUT CIRCUIT FOR AN OPEN
- Disconnect: SJB C2280e.
- Connect a fused jumper wire between the SJB C2280e-1, circuit CDC55 (BN/VT), harness side and the SJB C2280e-2, circuit CLF08 (YE/VT), harness side.
- Ignition ON.
- Do the high beams illuminate?
Yes
REMOVE the jumper wire. VERIFY the SJB fuse 23 (15A) is OK. If OK, GO to A7. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
No
For stripped chassis vehicles, LEAVE the jumper wire connected. GO to A6.
For all other vehicles, REMOVE the jumper wire. REPAIR circuit CLF08 (YE/VT) for an open. TEST the system for normal operation.
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A6 CHECK FOR VOLTAGE TO THE BODY BUILDER CONNECTOR
- Ignition OFF.
- Disconnect: Body Builder C1010.
- Ignition ON.
- Measure the voltage between the body builder C1010-3, circuit CLF08 (YE/VT), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
The vehicle is operating correctly. REMOVE the jumper wire. REFER to the body builder information to continue diagnosis.
No
REMOVE the jumper wire. REPAIR circuit CLF08 (YE/VT) for an open. TEST the system for normal operation.
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A7 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new SJB. 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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