Pinpoint Test B: Fuel Tank Selector Valve is Inoperative/Does Not Operate Correctly

Fuel System

Pinpoint Test B: Fuel Tank Selector Valve is Inoperative/Does Not Operate Correctly

Normal Operation

When the ignition switch is in the RUN or accessory position, voltage is supplied to the fuel tank selector switch through circuit CBP36 (WH/BN). A ground is supplied through circuit GD115 (BK/GY). When the fuel tank selector switch is in the front tank position, voltage is supplied to the fuel tank selector valve through circuit CE928 (YE/VT) and ground is supplied through circuit CE929 (VT/OG), which allows fuel to flow from the front fuel tank. When the fuel tank selector switch is in the rear tank position, voltage is supplied to the fuel tank selector valve through circuit CE929 (VT/OG) and ground is supplied through circuit CE928 (YE/VT), which allows fuel to flow from the rear fuel tank.

This pinpoint test is intended to diagnose the following:

- Circuitry

- Fuel tank selector switch

- Fuel tank selector valve

PINPOINT TEST B : FUEL TANK SELECTOR VALVE IS INOPERATIVE/DOES NOT OPERATE CORRECTLY

B1 CHECK THE FUEL TANK SELECTOR SWITCH FOR VOLTAGE

- Disconnect: Fuel Selector Switch C2194.

- Ignition ON.

- Measure the voltage between the fuel tank selector switch C2194-5, circuit CBP36 (WH/BN), harness side and C2194-2, circuit GD115 (BK/GY), harness side.





Is the voltage greater than 10 volts?

Yes
GO to B3.

No
GO to B2.

B2 CHECK THE FUEL TANK SELECTOR SWITCH GROUND FOR AN OPEN

- Measure the voltage between the fuel tank selector switch C2194-5, circuit CBP36 (WH/BN), harness side and ground.





Is the voltage greater than 10 volts?

Yes
REPAIR circuit GD115 (BK/GY) for an open. TEST the system for normal operation.

No
VERIFY Body Control Module (BCM) fuse 36 (10A) is OK. If OK, REPAIR circuit CBP36 (WH/BN). If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. TEST the system for normal operation. [1][2]Diagrams By Number

B3 CHECK FOR VOLTAGE TO THE FUEL TANK SELECTOR VALVE FOR THE FRONT TANK

- Connect: Fuel Selector Switch C2194.

- Disconnect: Fuel Selector Valve C3400.

- Set the fuel selector switch to front tank.

- Measure the voltage between the fuel tank selector valve C3400-4, circuit CE928 (YE/VT), harness side and fuel selector valve C3400-5, circuit CE929 (VT/OG), harness side.





Is the voltage greater than 10 volts?

Yes
GO to B7.

No
GO to B4.

B4 CHECK FOR VOLTAGE TO THE FUEL TANK SELECTOR VALVE FOR THE FRONT TANK AND CHASSIS GROUND

- Set the fuel selector switch to front tank.

- Measure the voltage between the fuel tank selector valve C3400-4, circuit CE928 (YE/VT), harness side and ground.





Is the voltage greater than 10 volts?

Yes
REPAIR circuit CE929 (VT/OG). TEST the system for normal operation.

No
GO to B5.

B5 CHECK THE FUEL TANK SELECT SWITCH CIRCUIT BETWEEN THE FUEL TANK SELECTOR VALVE AND THE FUEL TANK SELECTOR SWITCH

- Ignition OFF.

- Disconnect: Fuel Selector Switch C2194.

- Measure the resistance between the fuel tank selector valve C3400-4, circuit CE928 (YE/VT), harness side and fuel tank selector switch C2194-6, circuit CE928 (YE/VT), harness side.





Is the resistance less than 5 ohms?

Yes
GO to B6.

No
REPAIR circuit CE928 (YE/VT). TEST the system for normal operation.

B6 CHECK THE FUEL TANK SELECT SWITCH #2 CIRCUIT FOR AN OPEN

- Measure the resistance between the fuel tank selector valve C3400-5, circuit CE929 (VT/OG), harness side and fuel tank selector switch C2194-3, circuit CE929 (VT/OG), harness side.





Is the resistance less than 5 ohms?

Yes
INSTALL a new fuel tank selector switch. TEST the system for normal operation.

No
REPAIR circuit CE929 (VT/OG). TEST the system for normal operation.

B7 CHECK FOR VOLTAGE TO THE FUEL TANK SELECTOR VALVE FOR THE REAR TANK

- Set the fuel selector switch to rear tank.

- Measure the voltage between the fuel tank selector valve C3400-5, circuit CE929 (VT/OG), harness side and fuel selector valve C3400-4, circuit CE928 (YE/VT), harness side.





Is the voltage greater than 10 volts?

Yes
INSTALL a new fuel tank selector valve. TEST the system for normal operation.

No
GO to B8.

B8 CHECK THE FUEL TANK SELECT #2 CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: Fuel Selector Switch C2194.

- Measure the resistance between the fuel tank selector valve C3400-5, circuit CE929 (VT/OG), harness side and fuel tank selector switch C2194-4, circuit CE929 (VT/OG), harness side.





Is the resistance less than 5 ohms?

Yes
GO to B9.

No
REPAIR circuit CE929 (VT/OG). TEST the system for normal operation.

B9 CHECK THE FUEL TANK SELECT SWITCH CIRCUIT FOR AN OPEN

- Measure the resistance between the fuel tank selector valve C3400-4, circuit CE928 (YE/VT), harness side and fuel tank selector switch C2194-1, circuit CE928 (YE/VT), harness side.





Is the resistance less than 5 ohms?

Yes
INSTALL a new fuel tank selector switch. TEST the system for normal operation.

No
REPAIR circuit CE928 (YE/VT). TEST the system for normal operation.