P1172

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

CIRCUIT DESCRIPTION
The Secondary fuel pump is located in the rear fuel tank. The secondary fuel pump is powered by a secondary fuel pump relay which is separate from the primary fuel pump relay. Fuel is transferred from the secondary pump into the front tank to balance the fuel levels in both tanks depending on fuel level differences. The secondary fuel pump relay supply voltage is received from the primary fuel pump relay when the primary fuel pump is energized. This DTC is set when the secondary fuel pump is commanded on by the PCM and the PCM does not see a predetermined change in both the front and rear fuel level sensors.

CONDITIONS FOR RUNNING THE DTC
The engine is running
^ The vehicle speed is 0 mph
^ No active fuel level sensor DTC's
^ The above conditions are met for 20 seconds before the secondary pump is commanded on
^ The secondary fuel pump is commanded on for 120 seconds

CONDITIONS FOR SETTING THE DTC
The PCM does not detect a change of 4 Liters (1.06 gallons) in both the primary and secondary fuel level sensors with the secondary pump commanded on for 120 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

CONDITIONS FOR CLEARING THE DTC
^ A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
^ A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ Use a scan tool in order to clear the DTC.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. It is necessary to command the primary fuel pump ON to supply voltage at the secondary fuel pump supply voltage circuit.