Normal Operation
The fuel tank is a saddle tank design with variable resistance senders, driven by floats, that provide resistances related to fuel height, to the smart junction box (SJB). The fuel level is determined using a variable resistance fuel sender unit, with an approximate resistance range between 15 ohms at empty (E) and 160 ohms at full (F) ± 1%. The fuel pump sender is hardwired to the SJB through the signal circuit 1356 (LG/VT) and the return circuit 1357 (LB/YE). The remote fuel sender is hardwired to the SJB through the signal circuit 29 (YE/WH) and the return circuit 1357 (LB/YE). The SJB monitors the resistance readings that are sent to the SJB from the fuel senders and sends the instrument cluster a message over the communication network to command the fuel gauge with a corresponding movement of the pointer. If the remote fuel sender is open, the fuel gauge defaults to the fuel pump sender value only and the fuel gauge indicates E to 1/2 tank. If the fuel pump sender is open, the fuel gauge defaults to the empty position.
Possible Causes
circuit 29 (YE/WH) open, short to ground, or short to voltage
circuit 1356 (LG/VT) open, short to ground, or short to voltage
circuit 1357 (LB/YE) open, short to ground, or short to voltage
fuel pump sender
remote fuel sender
SJB
fuel tank
instrument cluster
PINPOINT TEST B: INCORRECT FUEL GAUGE INDICATION
Test Step Result / Action to Take
B1 RETRIEVE THE RECORDED INSTRUMENT CLUSTER AND SMART JUNCTION BOX (SJB) DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND SELF-TESTS
Check for recorded SJB DTCs from the continuous and on-demand self-tests.
Are any instrument cluster or SJB DTCs recorded?
Yes
If DTC B1201, B1202, B1204, B2627, or B2628, are retrieved, GO to B6.
For all other SJB DTCs, REFER to the Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index.
No
GO to B2.
B2 CARRY OUT THE INSTRUMENT CLUSTER FUEL GAUGE ACTIVE COMMAND USING THE DIAGNOSTIC TOOL
Key in ON position.
Enter the following diagnostic mode on the diagnostic tool: Instrument Cluster Active Command.
Select the instrument cluster fuel level control active command. Trigger, monitor, and scroll the fuel level at: 0%, 50%, and 100%.
Did the fuel gauge needle start at empty (E), move to half at 50%, and full (F) at 100%?
Yes
GO to B3.
No
GO to B13.
B3 CHECK THE FUEL PUMP SENDER RESISTANCE READING
NOTE: The fuel pump module resistance varies from 15 ± 1 ohms when empty (E) to 160 ± 1 ohms when full (F).
Key in OFF position.
Disconnect: Fuel Pump Sender C433.
Measure the resistance between the fuel pump sender C433 pin 2, component side and the fuel pump sender C433 pin 4, component side.
Is the resistance within specifications?
Yes
GO to B4.
No
GO to B5.
B4 CHECK THE REMOTE FUEL SENDER RESISTANCE READING
NOTE: The remote fuel sender resistance varies from 19 ± 2 ohms when empty (E) to 160 ± 4 ohms when full (F).
Disconnect: Remote Fuel Sender C434.
Measure the resistance between the remote fuel sender C434 pin 2, component side and the remote fuel sender C434 pin 4, component side.
Is the resistance within specifications?
Yes
CONNECT the fuel pump sender and the remote fuel sender. GO to B6.
No
GO to B5.
B5 INSPECT THE FUEL TANK
Visually inspect the fuel tank for any damage or deformation.
Is the fuel tank OK?
Yes
INSTALL a new fuel pump sender or remote fuel sender as necessary. REFER to Section 310-01. TEST the system for normal operation.
No
INSTALL a new fuel tank. REFER to Section 310-01. TEST the system for normal operation.
B6 CHECK CIRCUIT 29 (YE/WH), CIRCUIT 1356 (LG/VT) AND CIRCUIT 1357 (LB/YE) FOR A SHORT TO GROUND WITH THE SMART JUNCTION BOX (SJB) DISCONNECTED
Key in OFF position.
Disconnect: SJB C2280c.
Measure the resistance between the SJB connector, harness side and ground as follows:
SJB Connector-Pin Circuit
C2280c-31 1357 (LB/YE)
C2280c-43 29 (YE/WH)
C2280c-44 1356 (LG/VT)
Are the resistances greater than 10,000 ohms?
Yes
GO to B8.
No
GO to B7.
B7 CHECK CIRCUIT 29 (YE/WH), CIRCUIT 1356 (LG/VT) AND CIRCUIT 1357 (LB/YE) FOR A SHORT TO GROUND WITH THE FUEL PUMP SENDER AND THE REMOTE FUEL SENDER DISCONNECTED
Disconnect: Fuel Pump Sender C433.
Disconnect: Remote Fuel Sender C434.
Measure the resistance between the SJB connector, harness side and ground as follows:
SJB Connector-Pin Circuit
C2280c-31 1357 (LB/YE)
C2280c-43 29 (YE/WH)
C2280c-44 1356 (LG/VT)
Are the resistances greater than 10,000 ohms?
Yes
INSTALL a new fuel pump sender or remote fuel sender as necessary. REFER to Section 310-01. Clear the DTCs. REPEAT the self-test.
No
REPAIR the circuit in question. Clear the DTCs. REPEAT the self-test.
B8 CHECK CIRCUIT 29 (YE/WH), CIRCUIT 1356 (LG/VT) AND CIRCUIT 1357 (LB/YE) FOR A SHORT TO VOLTAGE
Key in ON position.
Measure the voltage between the SJB connector, harness side and ground as follows:
SJB Connector-Pin Circuit
C2280c-31 1357 (LB/YE)
C2280c-43 29 (YE/WH)
C2280c-44 1356 (LG/VT)
Is any voltage present?
Yes
GO to B9.
No
GO to B10.
B9 CHECK CIRCUIT 29 (YE/WH), CIRCUIT 1356 (LG/VT) AND CIRCUIT 1357 (LB/YE) FOR A SHORT TO VOLTAGE WITH THE FUEL PUMP SENDER DISCONNECTED
Key in OFF position.
Disconnect: Fuel Pump Sender C433.
Disconnect: Remote Fuel Sender C434.
Key in ON position.
Measure the voltage between the SJB connector, harness side and ground as follows:
SJB Connector-Pin Circuit
C2280c-31 1357 (LB/YE)
C2280c-43 29 (YE/WH)
C2280c-44 1356 (LG/VT)
Is any voltage present?
Yes
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
No
INSTALL a new fuel pump sender. REFER to Section 310-01. CLEAR The DTCs. REPEAT the self-test.
B10 CHECK CIRCUIT 29 (YE/WH), CIRCUIT 1356 (LG/VT) AND CIRCUIT 1357 (LB/YE) FOR AN OPEN
Key in OFF position.
Disconnect: Fuel Pump Sender C433.
Disconnect: Remote Fuel Sender C434.
Measure the resistance between the SJB connector, harness side and the fuel pump sender connector, harness side; and between the SJB connector, harness side and the remote fuel sender connector, harness side as follows:
SJB Connector-Pin Remote Fuel Sender Connector-Pin Fuel Pump Sender Connector-Pin
C2280c-43
29 (YE/WH) C434-4
29 (YE/WH) —
C2280c-31
1357 (LB/YE) C434-2
1357 (LB/YE) —
C2280c-44
1356 (LG/VT) — C433-4
1356 (LG/VT)
C2280c-31
1357 (LB/YE) — C433-2
1357 (LB/YE)
Are the resistances less than 5 ohms?
Yes
GO to B11.
No
REPAIR the circuit in question. TEST the system for normal operation.
B11 CHECK THE FUEL PUMP SENDER FOR A SHORT
Measure the resistance between the fuel pump sender C433 pin 2, component side and the fuel pump sender C433 pin 1, component side; and between the fuel pump sender C433 pin 4, component side and the fuel pump sender C433 pin 1, component side.
Are the resistances greater than 10,000 ohms?
Yes
GO to B12.
No
INSTALL a new fuel pump sender. REFER to Section 310-01. CLEAR the DTCs. REPEAT the self-test.
B12 CHECK FOR CORRECT SJB OPERATION
Disconnect all the SJB connectors.
Check for:
corrosion
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. REFER to Section 419-10. 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. CLEAR the DTCs. REPEAT the self-test.
B13 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION
Disconnect the instrument cluster connector.
Check for:
corrosion
pushed-out pins
Connect the instrument cluster connector and make sure it seats correctly.
Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new instrument cluster. REFER to Instrument Cluster in this section. 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.