Diagnostic Aids

Perform this test when instructed during QUICK TEST  or if directed by other test procedures. This test is used to diagnose the following:

• Fuel pump driver module.
• Inertia Fuel Shutoff (IFS) switch.
• Wiring harness circuits (B+, FP, FPM, Ground, POWER-TO-PUMP and VPWR).
• Constant Control Relay Module (CCRM).
• Powertrain Control Module (PCM).

Fig 1: Fuel Pump Driver Module Test Circuit & Connector Terminals

1. 1) DTC P1233 Or P1234  Turn ignition off. Connect scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access FPM PID. If FPM PID is 20-80 percent, go to step 25). If FPM PID is not 20-80 percent, go to next step.
2. 2)  If engine will start, go to step 15). If engine will not start, verify IFS switch is set and go to next step.
3. 3)  Turn ignition off. Disconnect FPDM wiring harness connector. Turn ignition on. Measure voltage between connector terminals GND and POWER-TO-FPDM. If voltage is 10.5 volts or more, replace FPDM and repeat QUICK TEST . If voltage is less than 10.5 volts, go to step 7).
   NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 7). No test procedures have been omitted.
4. 7)  Leave ignition on and FPDM disconnected. Measure voltage between chassis ground and connector terminal POWER-TO-FPDM. If voltage 10.5 volts or more, repair open circuit and repeat QUICK TEST . If voltage is less than 10.5 volts, go to next step.
5. 8)  Turn ignition off. Leave FPDM disconnected. Disconnect CCRM. Measure voltage between chassis ground and terminal No. 11 (B+) of CCRM connector. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, check power supply fuse to CCRM. If fuse is blown, check for short to ground in B+ and POWER-TO-FPDM circuits. If power supply fuse to CCRM is okay, repair open circuit to CCRM and repeat QUICK TEST .
6. 9)  Turn ignition off. Leave FPDM and CCRM disconnected. Disconnect scan tester (if applicable). Measure resistance between negative battery terminal and terminal No. 18 (GND) of CCRM connector. If resistance is 5 ohms or more, repair open circuit to CCRM and repeat QUICK TEST . If resistance is less than 5 ohms, go to next step.
7. 10) Check POWER-TO-FPDM Circuit Continuity  Leave ignition off. Leave FPDM and CCRM disconnected. Measure resistance between POWER-TO-FPDM terminal of FPDM connector and terminal No. 5 of CCRM connector. If resistance is 5 ohms or more, go to step 13). If resistance is less than 5 ohms, reconnect FPDM and go to next step.
8. 11) Check VPWR Circuit Continuity  Leave ignition off. Leave CCRM disconnected. Disconnect EEC-V power relay. Measure resistance between VPWR terminal of EEC-V power relay connector and terminal No. 13 (VPWR) of CCRM connector. See Fig 2. If resistance is 5 ohms or less, replace CCRM and repeat QUICK TEST . If resistance is more than 5 ohms, repair open in VPWR circuit between EEC-V power relay and CCRM.
   Fig 2: EEC-V Power Relay Connector Terminals