Pinpoint Test A: Both High Beams Are Inoperative
Headlamps
Pinpoint Test A: Both High Beams Are Inoperative
Normal Operation
The Smart Junction Box (SJB) sends a voltage signal to the multifunction switch to monitor the high beam request. When the headlamp switch is in the HEADLAMPS ON position and the multifunction switch is placed in the HIGH BEAM position, the voltage signal to the multifunction switch is routed to ground, indicating a high beam request. The SJB (Smart Junction Box) then energizes the high beam relay (integrated into the SJB (Smart Junction Box)) which supplies voltage to the high beams.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Multifunction switch
- Body builder equipment
- SJB (Smart Junction Box)
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.
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
VERIFY the SJB (Smart Junction Box) fuse 23 (15A) is OK. If OK, GO to A5. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams.
No
GO to A2.
A2 CHECK FOR A VOLTAGE 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.
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. TEST the system for normal operation.
A4 CHECK THE HIGH BEAM REQUEST CIRCUIT FOR AN OPEN
- Disconnect: SJB (Smart Junction Box) C2280B.
- Measure the resistance between the multifunction switch C202B-9, circuit CLF17 (WH/OG), harness side and the SJB (Smart Junction Box) 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.
A5 CHECK THE HIGH BEAM OUTPUT CIRCUIT FOR AN OPEN
- Disconnect: SJB (Smart Junction Box) C2280E.
- Connect a fused jumper wire between the SJB (Smart Junction Box) C2280E-1, circuit CDC55 (BN/VT), harness side and the SJB (Smart Junction Box) C2280E-2, circuit CLF08 (YE/VT), harness side.
- Ignition ON.
Do the high beams illuminate?
Yes
REMOVE the jumper wire. GO to A7.
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.
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 manual to continue diagnosis.
No
REMOVE the jumper wire. REPAIR circuit CLF08 (YE/VT) for an open. TEST the system for normal operation.
A7 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION
- Disconnect all the SJB (Smart Junction Box) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB (Smart Junction Box) 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 (Smart Junction Box). 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.