Diagnostic Aids

Perform this test when instructed by QUICK TEST, or when directed by other test procedures.

This test is intended to diagnose only the following:

• Fuel Pump Relay
• Inertia Switch
• Harness Circuits (BATT +, VPWR, FUEL PUMP, GND & POWER To PUMP)
• ECA

Application	Wire Color
Pin 19 (FPM)	Pink/Black
Pin 22 (FP)	Light Green
Pin 37/57 (VPWR)	White/Red

1) No Fuel Pump Pressure: Check Fuel Pump Electrical Operation  Turn ignition from OFF to RUN position several times (DO NOT turn to START position). If fuel pumps run briefly each time ignition is turned to RUN position, fuel pump circuit is okay. If fuel pumps do not run, go to next step.

2) Check For VPWR To ECA  With ignition off, install breakout box and reconnect ECA. Set DVOM on 20-volt scale. Turn ignition on, leaving engine off. Measure voltage between test pins No. 37 and 40 at breakout box. Measure voltage between test pins No. 57 and 60 at breakout box. If both voltage readings are greater than 10.5 volts, go to step 3. If voltage is not greater than 10.5 volts, go to TEST B, step 1.

3) Check Voltage To POWER-TO-PUMP(s) Circuit  With Key On Engine Off (KOEO), breakout box installed and ECA connected, set DVOM on 20-volt scale. Measure voltage between chassis ground and POWER-to-PUMP circuit at fuel pump relay while cranking engine. If reading is less than 8 volts, go to next step. If reading is 8 volts or more, check the following: open in POWER-to-PUMP circuit, open in fuel pump, and open fuel pump ground circuit.

4) Checking BATT (+) Circuit To Fuel Pump Relay  Turn ignition on, leaving engine off. Leave breakout box installed and ECA connected. Locate fuel pump relay. Set DVOM on 20-volt scale. Measure voltage between chassis ground and BATT (+) circuit at fuel pump relay. If reading is less than 10.5 volts, repair open in BATT (+) circuit between fuel pump relay and battery positive post. Repeat QUICK TEST. If reading is 10.5 volts or greater, go to next step.

5) Check Voltage At POWER-TO-PUMP(s) Circuit  With ignition off, breakout box installed and ECA connected, set DVOM on 20-volt scale. Connect jumper wire from test pin No. 22 to test pin No. 40 or 60 at breakout box. Turn ignition on, leaving engine off. Measure voltage between chassis ground and POWER-to-PUMP circuit at fuel pump relay. If voltage is greater than 10.5 volts, replace ECA. Remove breakout box and rerun QUICK TEST. If voltage is less than 10.5 volts, replace fuel pump relay. Remove breakout box, reconnect ECA and rerun QUICK TEST.

7) Code 87/556: Checking VPWR Circuit To Fuel Pump Relay  Code 87/556 indicates a fuel pump primary circuit failure. Possible causes for this fault are as follows:

• Inertia switch not reset or electrically open
• Open or shorted circuit
• Faulty fuel pump relay
• Faulty ECA

Turn ignition on, leaving engine off. Set DVOM on 20-volt scale. Disconnect fuel pump relay. Measure voltage between chassis ground and VPWR circuit at fuel pump relay. If reading is 10.5 volts or more, go to next step. If reading is less than 10.5 volts, ensure inertia switch is on. If inertia switch will not reset, replace switch. If switch is okay, repair open in VPWR circuit between EEC power relay and fuel pump relay. Reconnect fuel pump relay and repeat QUICK TEST.

8) Check Fuel Pump Relay  Turn ignition off and wait 10 seconds. Disconnect fuel pump relay. With DVOM on 200-ohm scale, measure resistance between VPWR pin and Fuel Pump circuit pin at fuel pump relay. Resistance should be 40-85 ohms.

Set DVOM to 20-k/ohm scale. Measure resistance between Fuel Pump circuit pin and both POWER-to-PUMP and BATT (+) pins at fuel pump relay. Both resistances should be greater than 10 k/ohms. If all resistances are as specified, go to next step. If resistances are not as specified, replace fuel pump relay and rerun QUICK TEST.

9) Check For Short To Power  With ignition off, disconnect 60-pin ECA connector and fuel pump relay. Install breakout box and leave ECA disconnected. Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between test pin No. 22 and battery negative terminal. If voltage is less than one volt, go to next step. If voltage is not less than one volt, repair short circuit. Reconnect ECA and attempt to start vehicle. If vehicle fails to start, replace ECA. Rerun QUICK TEST.

10) Check For Shorts To Ground  Turn ignition off and wait 10 seconds. Leave breakout box installed and ECA disconnected. Disconnect fuel pump relay. With DVOM on 200-k/ohm scale, measure resistance between test pin No. 22 and test pins No. 40 and 60. If reading is less than 10 k/ohms, repair short in FUEL PUMP circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST. If reading is 10 k/ohms or more, go to next step.

11) Check Fuel Pump Circuit Continuity  Turn ignition off. Leave breakout box installed and ECA disconnected. Set DVOM to 200-ohm scale. Disconnect fuel pump relay. Measure resistance between fuel pump circuit at fuel pump relay vehicle harness connector and test pin No. 22 at breakout box. If resistance is less than 5 ohms, replace ECA. Reconnect fuel pump relay and rerun QUICK TEST. If resistance is greater than 5 ohms, repair open circuit. Remove breakout box, reconnect all components and rerun QUICK TEST.

20) Code 95/542: Does Engine Start?  A KOEO Code 95/542 indicates one of the following conditions has occurred: