Code 88

Measure resistance between test pin No. 35 at the breakout box and EDF circuit at EDF relay vehicle harness connector. If resistance is less than 5 ohms, go to next step. If not, 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 key on. Measure voltage between test pin No. 31 (HEDF) or 32 (EDF) at the breakout box and battery negative terminal. If voltage is less than one volt, go to next step. If not, 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 key 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 the breakout box. If resistance is greater than 10 k/ohms, replace the ECA. Remove breakout box, reconnect all components and repeat QUICK TEST. If resistance is less than 10 k/ohms, repair short circuit. If Code 83 is present, ensure A/C high pressure switch is open. 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 key off, disconnect EDF relay. Set DVOM on 20-volt scale. With KOEO, measure voltage between SHORT CONNECTOR (shorted for non-A/C) input pin at the EDF relay vehicle harness connector and battery negative terminal. If voltage is greater than 10.5 volts, go to step 13). If not, for A/C equipped vehicles, go next step. For non-A/C vehicles, verify condition of jumper at SHORT CONNECTOR and operation of ignition relay. If these are okay, repair open circuit. Reconnect EDF relay. Recheck the system or re-evaluate the driveability symptom.

Fig 1: EDF Vehicle Harness Connector

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

Fig 2: HEDF Relay Harness Connector

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

Fig 3: EDF & HEDF Relay Harness Connectors

13) Check Circuits From EDF Relay To Fan With key off, disconnect EDF relay. Install a jumper wire from SHORT CONNECTOR input terminal to POWER-TO-FAN terminal at the EDF relay vehicle harness connector. Turn key on. If fan operates, remove jumper and go to step 16) for vehicles equipped with A/C. For non-A/C vehicles, replace EDF relay. Recheck system. If fan does not operate, remove jumper wire and go to next step.

Fig 4: EDF Relay Harness Connector

14) Check EDF POWER-TO-FAN Circuit Continuity With key off, disconnect EDF relay and cooling fan. Set DVOM on 200-ohm scale. Measure resistance between EDF POWER-TO-FAN output terminal at the EDF vehicle harness connector and the EDF POWER-TO-FAN input pin at the 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 5: EDF & Cooling Fan Vehicle Harness Connector

15) Check Cooling Fan Ground Circuit With key off, disconnect EDF relay. Disconnect cooling fan. Set DVOM 200-ohm scale. Measure resistance between GND circuit at the 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 key off, disconnect EDF relay. Disconnect A/C high pressure (A/C HP) switch. Install a jumper wire between the 2 terminals of the A/C HP switch vehicle harness connector. Turn key on. If fan runs at high speed, replace EDF relay. Remove jumper wire. Reconnect A/C HP switch. Recheck symptom. If fan does not run at high speed, remove jumper wire and reconnect ERDF relay. Go to next step.

17) Check Continuity of Circuits From A/C High Pressure Switch With key off, disconnect A/C HP switch and HEDF relay. Set DVOM on 200-ohm scale. Measure continuity from GND circuit at A/C HP switch vehicle harness connector and battery negative terminal. Measure continuity between signal output terminal (to HEDF relay) at A/C HP switch vehicle harness connector and A/C HP switch signal input terminal at HEDF relay vehicle harness connector. If each resistance is less than 5 ohms, go to next step. If not, repair open circuit. Reconnect all components and recheck symptoms. If symptom is still present, return to step 16) in this test.

Fig 6: HEDF & AC HP Switch Vehicle Harness Connector

18) Check HEDF POWER-TO-FAN Voltage at Fan With A/C HP Switch Grounded With key off, disconnect A/C HP switch and cooling fan. Reconnect HEDF relay. Set DVOM on 20-volt scale. Install a jumper wire between the 2 terminals of the A/C HP switch vehicle harness connector. Turn key on, measure voltage between HEDF POWER-TO-FAN circuit at the cooling fan vehicle harness connector and the battery negative terminal. If voltage is greater than 10.5 volts, replace cooling fan. Remove jumper wire and reconnect all components. Recheck system operation. If voltage is not greater than 10.5 volts, remove jumper wire. Reconnect A/C HP switch and go to next step.

Fig 7: Cooling Fan Vehicle Harness Connector

19) Check HEDF POWER-TO-FAN Circuit Continuity Turn key off. Disconnect cooling fan and HEDF relay. Set DVOM on 200-ohm scale. Measure resistance between the HEDF POWER-TO-FAN output terminal at the HEDF vehicle harness connector and the HEDF POWER-TO-FAN input terminal at the 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 19) 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 is Opening Turn A/C off during this test. Check cooling fan with key in OFF and ON positions. If cooling fan is always on with key off, but operates normally with key 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 key off and disconnect EDF relay. Turn key on. If fan continues to run, go to next step for vehicles equipped with A/C. For non-A/C vehicles, repair short to power in EDF POWER-TO-FAN circuit. Reconnect EDF relay. Recheck system operation. If vehicle does not continue to run, replace EDF relay and recheck system operation.

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

28) Check EDF POWER-TO-FAN Circuit For Short to Power Turn key off. Disconnect EDF and HEDF relays. Disconnect cooling fan. Set DVOM on 20-volt scale. Turn key on. Measure voltage between EDF POWER-TO-FAN circuit at the cooling fan vehicle harness connector and battery negative terminal. If voltage is greater than 1.0 volt, repair short-to-power in EDF POWER-TO-FAN circuit. Reconnect all components. Recheck system operation. If voltage is not greater than 1.0 volt, repair short-to-power in HEDF POWER-TO-FAN circuit. Reconnect all components. Recheck system operation.

Fig 9: Cooling Fan Vehicle Harness Connector