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Home >> Ford >> 1993 >> Crown Victoria Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - EEC-IV >> Circuit Tests >> Circuit Test XB - Variable Control Relay Module (VCRM) >> Engine Starts
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Engine Starts

Check if engine will start and idle for one minute. If engine starts and idles for one minute, go to step 121). If engine does not start or starts but does not idle for one minute, go to step 130).

121) Verify Fuel Pump Is Off  Turn ignition on, and wait 5 minutes. Listen for motor noise from fuel pump. If fuel pump is off, go to step 126). If fuel pump is on, go to step 122).

122) Check VCRM  Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Listen for fuel pump noise. If fuel pump is off, turn ignition off. Replace VCRM. Reconnect all components. Repeat QUICK TEST. If fuel pump is on, turn ignition off and go to step 123).

123) Check HFP Relay & Circuits  Turn ignition off. Ensure VCRM is disconnected. Disconnect HFP relay. Relay is located in engine compartment fuse block. Turn ignition on. Listen to fuel pump. If fuel pump is off, go to step 124). If fuel pump is on, turn ignition off. Repair short to power in power-to-fuel pump/FPM circuit. Reconnect all components. Repeat QUICK TEST.

124) Check For Short To Ground In HFP Circuit  Turn ignition off. Ensure VCRM and HFP relay are disconnected. Measure resistance between negative battery post and terminal No. 10 (Brown/White wire) at VCRM connector. If resistance is more than 10,000 ohms, replace HFP relay. Reconnect all components. Repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short to ground in HFP circuit. Reconnect all components. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 124) to step 126). No test procedures have been omitted.

126) Check FPM Circuit Continuity  Turn ignition off. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Install breakout box. Leave PCM disconnected. Disconnect HFP relay. Measure resistance between test pin No. 8 at breakout box and power-to-fuel pump terminal (Pink/Black wire) at HFP relay connector. See Fig 1. If resistance is less than 5 ohms, go to step 127). If resistance is 5 ohms or more, repair open in FPM circuit between PCM and splice to power-to-fuel pump circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

Fig 1: High Speed Fuel Pump (HFP) Relay Connector Terminals
G93F40688

127) Check For Short To Power In Left HO2S  Turn ignition off. Disconnect left HO2S. Measure resistance between HO2S SIGNAL terminal and KEY POWER terminal at HO2S connector. See Fig 2. If resistance is more than 10,000 ohms, to step 128). If resistance is 10,000 ohms or less, replace HO2S. Reconnect all components. Repeat QUICK TEST.

Fig 2: Identifying Heater Oxygen Sensor (HO2S) Terminals
G93J40690

128) Check For Short To Power In Left HO2S Circuit  Turn ignition off. Ensure left HO2S is disconnected. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Turn ignition on. Measure voltage between negative battery post and HO2S SIGNAL terminal at HO2S connector. See Fig 2. If voltage is less than 2 volts, replace PCM. Reconnect all components. Repeat QUICK TEST. If voltage is 2 volts or more, repair short to power in left HO2S circuit.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 128) to step 130). No test procedures have been omitted.

130) Check Inertia Fuel Shutoff (IFS) Switch  Turn ignition off. Disconnect IFS switch. IFS switch is located in left front of trunk. Ensure IFS switch button is in the down (set) position. Measure resistance between IFS switch terminals. If resistance is less than 5 ohms, reconnect IFS switch. Check for open in power-to-fuel pump circuit, open in fuel pump or poor fuel pump ground. Repair wiring as necessary. Repeat QUICK TEST. If resistance is 5 ohms or more, replace IFS switch. Reconnect all components. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 130) to step 135). No test procedures have been omitted.

135) Code 524, 543 & Continuous Memory Code 583  KOEO Code 524 or 543 indicates that when PCM commanded fuel pump on, voltage was not detected on Fuel Pump Monitor (FPM) circuit (PCM terminal No. 8). Code 524 refers to low speed output (VCRM terminal No. 24; Pink/Black wire). Code 543 refers to high speed output. It is not possible to distinguish between circuits due to vehicle wiring and fuel pump operating strategy. Continuous Memory Code 583 indicates that when fuel pump was activated, power-to-fuel pump exceeded normal current draw. This could be due to a hard fault or an intermittent condition. Following are possible causes for these faults.

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