Diagnostic Aids

Perform this test only when Code 83/563 or 88/564, is displayed during QUICK TEST or directed here by a driveability symptom. This test is intended to diagnose only the following components or circuits:

Harness circuits (EDF, HEDF, EDF POWER-TO-FAN, HEDF POWER-TO-FAN, IGN START/RUN and GND)
EDF and HEDF relays
Cooling fan
ECA

Fig 1: EDF/HEDF Circuit

CODE-TO-TEST PIN IDENTIFICATION

Circuit (Relay)	Test Pin No.
Code 83/563 HEDF (Relay No. 2)	31
Code 88/564 EDF (Relay No. 1)	35

3.0L SPFI (AXODE) TEST PIN WIRE COLOR IDENTIFICATION

Application	Wire Color
Pin 31 (HEDF)	Light Green/Purple
Pin 40 (PWR GND)	Black/Light Green
Pin 60 (PWR GND)	Black/Light Green

1) Code 83/563 or 88/564: Check For IGNITION START/RUN Voltage At EDF/HEDF Relay Code 83/563 indicates faulty HEDF primary circuit. Code 88/564 indicates faulty EDF primary circuit. Possible causes for these faults are as follows:

Open or shorted circuit
Faulty fan relay
Faulty ECA

With ignition off, disconnect EDF and HEDF relays. Set Digital Volt-Ohmmeter (DVOM) on 20-volt scale. With KOEO, measure voltage between IGN START/RUN circuit (at EDF/HEDF relay vehicle harness connector) and chassis ground. If voltage is greater than 10.5 volts, go to next step. If voltage is not as specified, repair open circuit. Reconnect relays. Go to QUICK TEST.

2) Enter Output State Check Use an analog Volt-Ohmmeter (VOM) or DVOM for this test. Turn ignition off and wait 10 seconds. Set DVOM on 20-volt scale. Disconnect electrical connector on speed control servo (if equipped). Connect DVOM negative lead to STO at self-test connector, and positive lead to battery positive post. Jumper STI or SIG RTN at the self-test connector. Perform KOEO SELF-TEST until Continuous Memory Code output is complete. See KOEO SELF-TEST under QUICK TEST near the beginning of this article. When DVOM indicates less than one volt, depress and release throttle. If voltage increases to greater than 10.5 volts, stay in output state check and go to next step. If voltage does not increase to at least 10.5 volts, depress throttle to wide open throttle and release. If STO voltage increases to specification, leave equipment connected and go to TEST QC, step 2).

3) Check For EDF/HEDF Circuit Cycling With vehicle still in output state check, disconnect EDF or HEDF relay. Set DVOM on 20-volt scale. Connect DVOM positive test lead to IGN START/RUN circuit and negative test lead to EDF or HEDF circuit at relay vehicle harness connector. Depress throttle to cycle off outputs. Observe DVOM and depress throttle again. For EDF, wait until CHECK ENGINE light flashes once (about 10 seconds). For HEDF, wait until CHECK ENGINE light flashes twice (about 15 seconds). Release throttle. EDF/HEDF output is now on. To cycle off output, depress and release throttle. If voltage cycles (about a 1-volt change), replace EDF or HEDF relay. Remove jumper and repeat QUICK TEST. If voltage does not cycle, remove jumper and go to next step.

4) Check Continuity of EDF/HEDF Circuit Turn ignition off and disconnect EDF or HEDF relay. Disconnect ECA 60-pin connector. Inspect for corroded or damaged connector pins and repair as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Perform the following appropriate check:

Code 83/563 - Measure resistance between test pin No. 31 at breakout box and HEDF circuit at HEDF relay vehicle harness connector.
Code 88/564 - Measure resistance between test pin No. 35 at breakout box and EDF circuit at EDF relay vehicle harness connector.

If resistance is less than 5 ohms, go to next step. If is not less than 5 ohms, repair open circuit. Remove breakout box and reconnect all components. Rerun QUICK TEST.

5) Check EDF/HEDF Circuit For Short To Power With breakout box installed, leave ECA disconnected. Disconnect EDF or HEDF relay. Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between test pin No. 31 (HEDF) or 35 (EDF) at the breakout box 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. Remove breakout box and reconnect all components. Rerun QUICK TEST. If code is still present, replace ECA.

6) Check EDF/HEDF Circuit For Short To Ground With ignition off, install breakout box, leaving ECA disconnected. Disconnect EDF or HEDF relay. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 31 (HEDF) or 35 (EDF) and test pins No. 40 and 60 at breakout box. If resistance is greater than 10 k/ohms, replace ECA. Remove breakout box, reconnect all components and repeat QUICK TEST. If resistance is less than 10 k/ohms, repair short circuit. Remove breakout box, reconnect all components and repeat QUICK TEST.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 6) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) Low-Speed (EDF) And/Or High-Speed (HEDF) Cooling Fan Does Not Operate: Check For Voltage To EDF Relay With ignition off, disconnect EDF relay. Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between HEDF relay pin (at EDF relay vehicle harness connector) and battery negative terminal. If voltage is greater than 10.5 volts, go to step 13). If voltage is not greater than 10.5 volts, go to next step.

Fig 2: EDF Relay Vehicle Harness Connector

11) Check For Voltage To HEDF Relay With ignition off, disconnect EDF and HEDF relays. Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between ignition relay input terminal (at HEDF relay vehicle harness connector) and battery negative terminal. If voltage is greater than 10.5 volts, go to next step. If voltage is not greater than 10.5 volts, check operation of ignition relay. If relay is okay, repair open circuit. Reconnect EDF and HEDF relays. Re-evaluate symptoms.

Fig 3: HEDF Relay Vehicle Harness Connector

12) Check Continuity Between EDF & HEDF Relays With ignition off, disconnect EDF and HEDF relays. Set DVOM on 200-ohm scale. Measure resistance between HEDF input terminal (at EDF relay vehicle harness connector) and the output to EDF terminal (at HEDF relay vehicle harness connector). If resistance is less than 5 ohms, replace HEDF relay. Reconnect all components. Re-evaluate symptom. If resistance is greater than 5 ohms, repair open circuit. Reconnect all components. Re-evaluate symptom.

Fig 4: EDF & HEDF Relay Harness Connectors

13) Check Circuits From EDF Relay To Fan With ignition off, disconnect EDF relay. Install a jumper wire between HEDF relay pin and POWER-TO-FAN pin at EDF relay vehicle harness connector. Turn ignition on. If fan operates, remove jumper and go to step 16). If fan does not operate, remove jumper wire and go to next step.

Fig 5: EDF Relay Vehicle Harness Connector

14) Check EDF POWER-TO-FAN Circuit Continuity With ignition off, disconnect EDF relay and cooling fan. Set DVOM on 200-ohm scale. Measure resistance between EDF POWER-TO-FAN output terminal (at EDF vehicle harness connector) and EDF POWER-TO-FAN input pin (at cooling fan vehicle harness connector). If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit. Reconnect all components. Re-evaluate driveability symptoms.

Fig 6: EDF & Cooling Fan Vehicle Harness Connector

15) Check Cooling Fan Ground Circuit With ignition off, disconnect EDF relay. Disconnect cooling fan. Set DVOM to 200-ohm scale. Measure resistance between GND circuit (at cooling fan vehicle harness connector) and battery negative terminal. If resistance is less than 5 ohms, replace cooling fan. Reconnect all components. Recheck symptom. If resistance is greater than 5 ohms, repair open circuit. Reconnect all components and recheck symptom.

16) Check Circuits From HEDF Relay To Fan With ignition off, disconnect EDF relay. Disconnect ECU 60-pin connector. Inspect for damaged or pushed out terminals, corrosion and loose wires. Repair as necessary. Install a breakout box and leave ECU disconnected. Install a jumper wire between test pin No. 31 and test pin No. 40 of breakout box. Turn ignition on. If fan runs at high speed, replace EDF relay. Remove breakout box. Recheck symptom. If fan does not run at high speed, remove jumper wire and go to next step.

17) Check HEDF Power-To-Fan Voltage At Fan With ignition off, disconnect HEDF relay and cooling fan. Install a jumper wire between test pin No. 31 and test pin No. 40 of breakout box. Turn ignition on. Measure voltage between HEDF POWER-TO-FAN circuit (at cooling fan vehicle harness connector) and battery negative terminal. If voltage is greater than 10.5 volts, replace cooling fan. Remove breakout box. Reconnect components and recheck symptom. If voltage is less than 10.5 volts, remove jumper wire and go to next step.

Fig 7: Cooling Fan Vehicle Harness Connector

18) Check HEDF POWER-TO-FAN Circuit Continuity Turn ignition off. Install a breakout box. Disconnect ECA. Disconnect cooling fan, HEDF and EDF relays. Set DVOM on 200-ohm scale. Measure resistance between HEDF POWER-TO-FAN output terminal (at HEDF vehicle harness connector) and HEDF POWER-TO-FAN input terminal (at cooling fan vehicle harness connector). If resistance is less than 5 ohms, replace HEDF relay. Reconnect all components. Recheck system operation. If resistance is greater than 5 ohms, repair open circuit. Reconnect all components and recheck system operation.

Fig 8: HEDF Relay Vehicle Harness Connector

NOTE: There is a break in the step numbering sequence at this point, skipping from step 18) to step 25). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

25) Low Speed (EDF) or High Speed (HEDF) Cooling Fan Always On: Ensure Ignition Relay Opens Turn A/C off during this test. Check cooling fan with ignition in OFF and ON positions. If cooling fan is always on with ignition off, but operates normally with ignition on, ensure IGNITION relay contacts are always closed. If relay is okay, check circuit from IGNITION relay to fan relays for a short to BATT (+). If system does not operate as described, go to next step.

26) Check For Relay Always Closed Turn ignition off and disconnect EDF relay. Turn ignition on. If fan continues to run, go to next step. If fan does not continue to run, replace EDF relay and recheck system operation.

27) Check HEDF Relay Turn ignition off. Disconnect EDF and HEDF relay. Turn ignition on. If fan continues to run, go to next step. If does not continue to run, replace HEDF relay. Reconnect EDF relay. Recheck system operation.

28) Check EDF POWER-TO-FAN Circuit For Short to Power Turn ignition off. Disconnect EDF and HEDF relays. Disconnect cooling fan. Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between EDF POWER-TO-FAN circuit (at cooling fan vehicle harness connector) and battery negative terminal. If voltage is greater than one volt, repair short to power in EDF POWER-TO-FAN circuit. Reconnect all components. Recheck system operation. If voltage is not greater than one volt, repair short to power in HEDF POWER-TO-FAN circuit. Reconnect all components. Recheck system operation.

Fig 9: Cooling Fan Vehicle Harness Connector