Engine Does Not Start

Open circuit in fuel pump or between fuel pump and FPM circuit.
Poor fuel pump ground connection.
Fuel pump internal circuit open.
IFS switch not reset or internal circuit open.

If engine starts, go to step 81). If engine does not start, go to step 85).

81) Verify Fuel Pump Is Off Turn ignition on. Wait 5 seconds. Listen for fuel pump operation. If pump is on, go to step 83) for models with gasoline fuel systems.

82) Check For LFP Relay Always Closed Turn ignition off. Disconnect LFP relay. Turn ignition on. Wait 5 seconds. Listen for fuel pump operation. If pump goes off when relay is disconnected, replace LFP relay and repeat QUICK TEST. If pump does not go off when relay is disconnected, go to step 83).

83) Check For Fuel Pump Relay Always Closed Turn ignition off. Disconnect CCRM. Turn ignition on. Wait 5 seconds. Listen for fuel pump operation. If pump goes off when relay is disconnected, replace CCRM and repeat QUICK TEST. If pump does not go off when CCRM is disconnected, repair short to power in POWER-TO-PUMP/FPM circuit.

84) Check Continuity Of FPM Circuit Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damage and repair as necessary. Install breakout box, leaving PCM disconnected. Disconnect CCRM. Measure resistance between test pin No. 8 at breakout box and pin No. 5 of CCRM wiring harness connector. If resistance is less than 5 ohms, go to step 86) (dual HO2S models) or replace PCM and repeat QUICK TEST (except dual HO2S models). If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST.

85) Check Inertia Fuel Shutoff (IFS) Switch Turn ignition off. Disconnect IFS switch. Measure resistance at IFS switch terminals "C" and NC. If resistance is 5 ohms or less, fault is in fuel pump electrical system. If resistance is more than 5 ohms, replace or reset IFS switch and repeat QUICK TEST.

86) Check Left/Front HO2S Sensor For Short To Power Turn ignition off. Disconnect left/front HO2S sensor. Measure resistance between HO2S SIGNAL terminal and KEY POWER terminal at HO2S sensor connector. See Fig 1 . If resistance is 10,000 ohms or more, go to step 87). If resistance is less than 10,000 ohms, replace HO2S sensor and repeat QUICK TEST.

Fig 1: HO2S Sensor Connector Terminal ID (X16)

87) Check HO2S Circuit For Short To Power Leave ignition off and left/front HO2S sensor disconnected. Disconnect PCM 60-pin connector. Inspect for damage and repair as necessary. Turn ignition on. Measure voltage between HO2S SIGNAL terminal at sensor wiring harness connector and chassis ground. See Fig 2 . If voltage is one volt or less, replace PCM and repeat QUICK TEST. If voltage is more than one volt, repair short circuit and repeat QUICK TEST.

Fig 2: HO2S Sensor Wiring Harness Connector Terminal (X17)

88) Code 524 If KOEO Code 543 is present, go to step 90). Code 524 indicates LFP secondary circuit failure. Following are possible causes for this fault.

Open B(+) circuit to LFP relay.
Open POWER-TO-PUMP circuit.
Faulty fuel pump dropping resistor.
Faulty LFP relay.

Turn ignition off. Disconnect LFP relay. Measure voltage between B(+) terminal of relay wiring harness connector and negative battery terminal. If less 10.5 volts is present, repair open in B(+) circuit. If 10.5 volts or more is present, go to next step.

89) Check POWER-TO-PUMP Circuit Continuity Leave ignition off and LFP relay disconnected. Disconnect CCRM. Measure resistance between terminal No. 5 of CCRM wiring harness connector and POWER-TO-PUMP terminal of LFP relay wiring harness connector. If resistance is less than 10 ohms, replace LFP relay. If resistance is 10 ohms or more, measure resistance across fuel pump dropping resistor terminals. If resistance is not approximately one ohm, replace fuel pump dropping resistor. If resistance is approximately one ohm, repair open in POWER-TO-PUMP circuit.

Fig 3: Checking POWER-TO-PUMP Circuit Continuity (X18)

90) Code 524/543 Code 524/543 indicates one of the following conditions.

Open circuit in fuel pump or between fuel pump and FPM circuit.
Fuel pump relay contacts always open.

If engine does not start, go to step 91). On dual HO2S applications go step 86); on single HO2S applications, replace PCM and repeat QUICK TEST.

91) Check B(+) To Fuel Pump Relay(s) Turn ignition off. Disconnect CCRM relay. Perform appropriate procedure.

Measure voltage between CCRM wiring harness connector terminal No. 11 and negative battery terminal.