P0127F-FUEL PUMP CONTROL CIRCUIT 2 OVERCURRENT (TIPM)
For a complete wiring diagramRefer to Section 8W.
When Monitored:
With the ignition on. Battery voltage greater than 10.4 volts. TIPM requesting Fuel Pump operation.
Set Condition:
An overcurrent condition is detected in the fuel pump control output circuit. One Trip Fault. Three good trips to
turn off the MIL.
Possible Causes
TERMINAL DAMAGE OR CORROSION
FUEL PUMP MOTOR GROUND HIGH RESISTANCE
(A109) FUEL PUMP CONTROL OUTPUT CIRCUIT HIGH RESISTANCE
FUEL PUMP MOTOR
TIPM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.FUEL PUMP OPERATION
Ignition on, engine not running.
With a scan tool in the TIPM Actuators, actuate the Fuel Pump.
Is the Fuel Pump operating?
Ye s>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 2
2.VISUAL AND PHYSICAL CONNECTOR AND TERMINAL INSPECTION
Turn the ignition off.
Disconnect the C10 TIPM harness connector.
Disconnect the Fuel Pump Module harness connector.
Inspect the terminal and connector condition. Check for signs of corrosion build up or damage the would compro-
mise the terminal to controller pin connector.
NOTE: Make sure that all in-line connectors are inspected for corrosion and/or damage.
Visually inspect the wiring harness. Look for any chafed, pierced, pinched or partially broken wires hidden in the
wire insulation.
Were any of the above conditions found?
Ye s>>
Repair or replace as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
3.(A109) FUEL PUMP CONTROL OUTPUT CIRCUIT HIGH RESISTANCE
With a jumper wire, connect one end to the (A109) Fuel Pump Control
Output circuit in the Fuel Pump Module harness connector and the
other to a clean chassis ground.
Using a 12-volt test light to battery voltage, probe the (A109) Fuel Pump
Control Output circuit in the C10 TIPM harness connector.
NOTE: The test light should be illuminated and bright. Compared
the brightness to that of a direct connection to the battery.
Does the test light illuminate brightly.
Ye s>>
Go To 4
No>>
Repair the excessive resistance in the (A109) Fuel Pump
Control Output circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE).
4.FUEL PUMP MOTOR GROUND CIRCUITS
Using a 12-volt test light to battery voltage, probe the (Z927) and (Z210)
Fuel Pump Motor Ground circuits in the Fuel Pump Motor harness con-
nector.
NOTE: The test light should be illuminated and bright. Compared
the brightness to that of a direct connection to the battery.
Does the test light illuminate brightly.
Ye s>>
Go To 5
No>>
Repair the excessive resistance in the Fuel Pump Motor
Ground circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
5.FUEL PUMP CONTROL OUTPUT FROM TIPM
Reconnect the C10 TIPM harness connector.
Ignition on, engine not running.
With a scan tool in the TIPM Actuators, actuate the Fuel Pump.
Using the 12-Volt test light connected to ground, probe the (A109) Fuel
Pump Control Output circuit in the Fuel Pump Module harness connec-
tor.
Does the test light illuminate brightly?
Ye s>>
Replace the Fuel Pump Module
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace the TIPM in accordance with the Service Informa-
tion.
Perform the BODY VERIFICATION TEST – VER 1. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
*ENGINE SURGES
Possible Causes
DTC/PRODUCT IMPROVEMENT
FUEL SUPPLY SYSTEM
INJECTION SYSTEM
FUEL RETURN
INTAKE SYSTEM
OTHER VEHICLE SYSTEMS
BASE ENGINE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.DTC/PRODUCT IMPROVEMENT
Check for any TSB’s related to customer’s complaint or DTC’s present.
Follow appropriate guidelines in DTC troubleshooting tree or instructions in TSB.
Is vehicle repaired?
Ye s>>
Repair complete.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 2
2.FUEL SUPPLY SYSTEM
Verify proper fuel quality, grade and level in vehicle.
Use scan tool to monitor fuel rail pressure. If pressure does not fluctuatemore then +/- 500 psi of setpoint than the
fuel system is not the cause of the complaint. Proceed to step3. If condition exist continue.
Verify proper low pressure supply to the Injection Pump by performing the “*IN-TANK FUEL LIFT PUMP FLOW
TEST - DIESEL” Procedure.
Use the “*HIGH PRESSURE FUEL PUMP PERFORMANCE TEST - DIESEL” to check for failed fuel pump.
Perform “*CHECKING PRESSURE LIMITING VALVE ON THE FUEL - DIESEL”.
Is vehicle repaired?
Ye s>>
Repair complete.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 3
4.ENGINE TIMING
Inspect speed indicator ring for damaged/missing teeth.
Inspect for dirty or damaged pins at Crankshaft position sensor (CKP) or Camshaft position sensor (CMP).
Verify proper overhead adjustments.
Is vehicle repaired?
Ye s>>
Repair complete.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 5
5.FUEL SUPPLY SYSTEM
Verify proper fuel quality, grade and level in vehicle.
Use scan tool to monitor fuel rail pressure. If pressure does not fluctuatemore then +/- 500 psi of setpoint than the
fuel system is not the cause of the complaint. Proceed to step 6. If condition exist continue.
Verify proper low pressure supply to the Injection Pump by performing the “*IN-TANK FUEL LIFT PUMP FLOW
TEST - DIESEL” Procedure.
Use the “*HIGH PRESSURE FUEL PUMP PERFORMANCE TEST - DIESEL” to check for failed fuel pump.
Perform “*CHECKING PRESSURE LIMITING VALVE ON THE FUEL - DIESEL”.
Is vehicle repaired?
Ye s>>
Repair complete.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 6
6.INJECTION SYSTEM
Perform “*INJECTOR RETURN FLOW TEST”. If okay go next step.
Check for correct injectors and injector shims.
Visuslly inspect injector wire nuts and pass through connectors for damageorcorrosion.
Is vehicle repaired?
Ye s>>
Repair complete.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 7
7.FUEL RETURN
Check for kinked or restricted fuel return lines.
Check fuel tank venting.
Is vehicle repaired?
Ye s>>
Repair complete.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 8
*IN-TANK FUEL LIFT PUMP FLOW/DIAGNOSTIC TEST PROCEDURE
Diagnostic Test
1.
1. Using the Scan tool, check for DTCs. Troubleshoot any active DTCs beforeperforming this test.
2. Disconnect the wiring harness from the lift pump at the fuel tank module connector and inspect the pins for
damage. Fix or replace any damaged component.
3. Connect a voltmeter between the fuel lift pump supply and return pins at the fuel tank module connector.
4. Turn the ignition to the on position. Use the Scan tool to actuate the fuellift pump, record the voltage on the
voltmeter.
5. If the voltage is greater than 11.5 volts, go to step 14. If the voltage is lessthan11.5volts,gotostep6
6. Using a voltmeter, measure the battery voltage to determine that the voltage is greater than 11.5 volts. If the
voltage is greater than 11.5 volts, go to step 7. If the voltage is not greater than 11.5 volts, troubleshoot for low
battery voltage.
7. Remove the fuel lift pump relay from the PDC. Use a voltmeter to measure the voltage at the fuel lift pump relay
voltage supply pin in the PDC. If the voltage is greater than 11.5 volts, go to step 8. If the voltage is not greater than
11.5 volts, fix or replace the harness.
8. Remove the fuel lift pump relay from the PDC. Install a spare relay in place of the fuel lift pump relay. Using the
Scan tool, actuate the fuel lift pump. Use a voltmeter to measure the voltage between the fuel lift pump supply and
return pins at the fuel tank module connector while the fuel lift pump is actuated. If the voltage is greater than 11.5
volts, replace the fuel lift pump relay. If the voltage is not greater than 11.5volts,gotostep9.
9. Disconnect the wiring harness from the fuel tank module. Remove the liftpump relay from the PDC. Using an
Ohmmeter, measure the resistance of the fuel lift pump power supply wire between the PDC relay output pin and
the fuel tank module connector. If the resistance is less than 10 ohms, go tostep 10. If it is greater than 10 ohms,
fix or replace the harness.
10. Disconnect the wiring harness from the fuel tank module. Remove the fuel lift pump relay from the PDC. Using
a voltmeter, measure the voltage between battery negative and the fuel lift pump power supply wire at the fuel
module connector. If the voltage is less than 1 volt, go to step 11. If the voltage is greater than 1 volt, fix or replace
the harness.
11. Disconnect the wiring harness from the fuel tank module. Remove the fuel lift pump relay from the PDC. Using
an ohmmeter, measure the resistance between battery negative and the fuellift pump power supply wire at the fuel
module connector. If the resistance is less than 10 ohms, fix or replace theharness. If the resistance is greater than
10 ohms, go to step 12.
12. Disconnect the wiring harness from the fuel tank module. Using an Ohmmeter, measure the resistance of the
fuel lift pump ground wire between the fuel tank module connector and battery negative. If the resistance is less
than 10 ohms, go to step 13. If the resistance is greater than 10 ohms, fix or replace the harness.
13. Disconnect the wiring harness from the fuel tank module. Using a voltmeter, measure the voltage between the
fuel lift pump ground wire and battery negative. If the voltage is less than1 volt, go to step 14. If the voltage is
greater than 1 volt, fix or replace the harness.
14. Reconnect the lift pump connector.
FLOW TEST.
1. Remove the fuel pump supply banjo fitting from the fuel injection pump.
2. Install Miller Tool #9014 fuel system test fitting into the fuel injection pump.
3. Connect one end of a section of fuel hose to the test fitting.
4. Put the other end of the fuel hose into an empty fuel container.
5. Use the scan tool to actuate the fuel lift pump.
6. While the lift pump is running, move the fuel hose from the fuel canister into a 1000ml graduated cylinder for 10
seconds.
7. Read and record the amount of fuel in the graduated cylinder after 10 seconds.
8. If you have more than 430ml in the graduated cylinder after 10 seconds, the test has successfully passed.
9. If you have less than 430ml of fuel in the graduated cylinder, inspect thefuel supply line from the fuel tank to the
fuel filter housing and the fuel supply line between the fuel filter housing and the high pressure fuel pump for signs
of damage, replace as necessary. If no damage is found, replace the fuel filter and retest.
10.Verify the Screened Banjo Bolt at the outlet of the fuel filter is free ofdebris. If debris is found, rinse screen with
water, blow dry and reinstall. Retest vehicle. If flow meets specification then trace back the source of debris, if flow
is still below spec repair damaged component.
11. If reading is still less than 430ml in 10 seconds, remove the fuel tank and fuel tank module. Inspect for damage
and/or debris in and around the fuel tank module. If module is damaged, replace and retest.
12. If the module is not damaged, replace the fuel lift pump and retest to confirm fix.
Test complete
Repair
Te s t c o m p l e t e .
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)