Starting System: Diagnosis Ford Explorer III

TROUBLE SHOOTING

Verify customer compliant by operating starting system. Check battery for state of charge. Check cable connections at battery and starter motor. Ensure transmission is fully engaged in Park or Neutral position. Check maxi-fuse No. 12 (50-amp) in battery junction box. (Scheme 1) Check fuse No. 29 (10-amp) in central junction box. (Scheme 2) On models equipped anti-theft system, ensure anti-theft system is operating properly. See appropriate ANTI-THEFT SYSTEMS article for additional information. If problem is found, repair as necessary. If problem is not found, repair by symptom. See SYMPTOM INDEX under SYSTEM TESTS.

Scheme 1

Scheme 2

TEST A: ENGINE DOES NOT CRANK & RELAY CLICKS

1. Ensure battery is fully charged and has sufficient capacity. Is the battery is okay? If yes, go to next step. If no, recharge or replace battery as necessary.
2. Measure voltage between positive battery post and battery ground cable connection at engine block. Is the voltage more than 10 volts? If yes, go to next step. If no, replace battery ground cable. Recheck system operation.
3. Measure voltage between positive battery post and starter motor case. Is the voltage more than 10 volts? If yes, go to next step. If no, clean starter motor mounting flange and ensure starter motor is properly mounted. Recheck system operation.
4. Turn ignition off. Measure voltage between ground and starter motor terminal "B" (Red wire). (Scheme 3) Is the voltage more than 10 volts? If yes, go to next step. If no, replace positive battery cable. Recheck system operation.
5. Momentarily connect a jumper wire between starter motor terminal "B" (Red wire) and starter motor solenoid terminal "S" (Yellow/Light Blue wire). (Scheme 3) Does the starter motor engage and crank the engine? If yes, go to next step. If no, replace starter motor. See «STARTER MOTOR»(ref-168028-S41421407872004102800000) under REMOVAL & INSTALLATION. Recheck system operation.
6. Disconnect starter motor solenoid "S" connector. Hold ignition switch in START position. Measure voltage between ground and starter motor solenoid terminal "S" harness connector (Yellow/Light Blue wire). Is the voltage more than 10 volts? If yes, clean starter solenoid terminal "S" and connector. Check wiring and starter motor for loose or intermittent connection. Recheck system operation. If no, go to next step.
7. Turn ignition off. Remove starter relay from Battery Junction Box (BJB). Hold ignition switch in START position. Measure voltage between ground and starter relay connector terminal No. 85 (White/Pink wire). (Scheme 4) Is the voltage reading more than 10 volts? If yes, go to next step. If no, go to step 13.
8. Turn ignition off. Measure voltage between ground and starter relay connector terminal No. 30 (Light Green/Violet wire). (Scheme 4) Is the voltage reading more than 10 volts? If yes, go to next step. If no, repair open in Light Green/Violet wire between starter relay connector and BJB. Recheck system operation. See «WIRING DIAGRAMS»(ref-168028-S29329301992004102800000).
9. Disconnect starter solenoid "S" terminal harness connector. Measure resistance between ground and starter relay connector terminal No. 87 (Yellow/Light Blue wire). (Scheme 4) Is the resistance reading less than 10 k/ohms? If yes, repair short to ground in Yellow/Light Blue wire between starter motor relay and starter motor. See «WIRING DIAGRAMS»(ref-168028-S29329301992004102800000). If no, go to next step.
10. Measure resistance of Yellow/Light Blue wire between starter relay connector terminal No. 87 and starter solenoid "S" harness connector. (Scheme 3)and (Scheme 4). Is the resistance reading less than 5 ohms? If yes, go to next step. If no, repair open or high resistance in Yellow/Light Blue wire between starter relay and starter. See «WIRING DIAGRAMS»(ref-168028-S29329301992004102800000). Recheck system operation.
11. Connect starter relay. Connect starter "S" Terminal. Disconnect PCM connector C175a. Connect a jumper wire between the PCM connector C175a terminal No. 39 (Orange wire) and ground. (Scheme 5) Turn ignition to START position. Did the engine crank? If yes, see appropriate PASSIVE ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT to diagnose the passive anti-theft system concern. If no, go to next step.
12. Turn ignition off. Disconnect starter relay. Measure the resistance of Orange wire between the starter relay connector terminal No. 86 and the PCM connector C175a terminal No. 39. (Scheme 4)and (Scheme 5). Is the resistance reading less than 5 ohms? If yes, install a new starter relay. Test the system for normal operation. If no, repair Orange wire for an open. Test the system for normal operation.
13. Turn ignition off. Remove fuse No. 29 (10-amp) from Central Junction Box (CJB). (Scheme 2) Check fuse for continuity. Is fuse No. 4 okay? If yes, go to next step. If no, go to step 20.
14. Hold ignition switch to START position. Measure voltage between ground and CJB box fuse No. 29 input cavity. (Scheme 2) Is the voltage reading more than 10 volts? If yes, go to step 18. If no, go to next step.
15. Disconnect ignition switch harness connector. Measure voltage between ground and ignition switch harness connector terminal No. 4 (Yellow wire). (Scheme 6) Is the voltage reading more than 10 volts? If yes, go to next step. If no, repair open in Yellow wire between BJB and ignition switch. See «WIRING DIAGRAMS»(ref-168028-S29329301992004102800000). Recheck system operation.
16. Measure resistance of Red wire between ignition switch harness connector terminal No. 7 and CJB fuse No. 29 input cavity. (Scheme 2)and (Scheme 6). Is the resistance reading less than 5 ohms? If yes, go to next step. If no, repair open or high resistance in Red wire. Recheck system operation. See «WIRING DIAGRAMS»(ref-168028-S29329301992004102800000).
17. Measure resistance between ground and ignition switch harness connector terminal No. 4 (Red wire). If resistance is less than 10 k/ohms, repair short to ground in Red wire between ignition switch harness connector and CJB. Recheck system operation. See «WIRING DIAGRAMS»(ref-168028-S29329301992004102800000). If resistance is 10 k/ohms or more, replace ignition switch. Recheck system operation.
18. Disconnect Digital Transmission Range (DTR) sensor harness connector. Measure resistance between DTR sensor harness connector terminal No. 12 (Red/Light Blue wire) and CJB fuse No. 29 output cavity (Red/Light Blue wire). (Scheme 2)and (Scheme 7). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Red/Light Blue wire between DTR sensor and CJB. See «WIRING DIAGRAMS»(ref-168028-S29329301992004102800000). Recheck system operation.
19. Measure the resistance of White/Pink wire between the starter relay connector terminal No. 85 and the DTR sensor harness connector terminal No. 10. Is the resistance reading less than 5 ohms? If yes, check the DTR sensor adjustment. See «DIGITAL TRANSMISSION RANGE SENSOR»(ref-168028-S42222544432004102800000) under ADJUSTMENTS. If the DTR sensor is adjusted correctly, install a new DTR sensor. Test The system for normal operation. If no, repair White/Pink wire for an open. Test the system for normal operation.
20. Remove starter relay from BJB. Measure resistance between ground and CJB fuse No. 29 output cavity (Red/Light Blue wire). Is the resistance greater than 10 k/ohms? If yes, check all wires for chafed wires or intermittent short to ground. Check connectors for poor terminal contact. Replace fuse No. 29. Recheck system operation. If no, go to next step.
21. With DTR sensor harness connector disconnected and starter relay removed, measure resistance between ground and CJB fuse No. 29 output (Red/Light Blue wire). (Scheme 2) Is the resistance greater than 10 k/ohms? If yes, go to next step. If no, repair short to ground in Red/Light Blue wire between CJB and DTR sensor. See «WIRING DIAGRAMS»(ref-168028-S29329301992004102800000).
22. Measure resistance between ground and DTR sensor harness connector terminal No. 10 (White/Pink wire). Is the resistance reading more than 10 k/ohms? If yes, check DTR sensor adjustment. See «DIGITAL TRANSMISSION RANGE SENSOR»(ref-168028-S42222544432004102800000) under ADJUSTMENTS. If DTR sensor adjustment is okay, replace DTR sensor. Recheck system operation. If no, repair short to ground in White/Pink wire between DTR sensor and starter relay. See «WIRING DIAGRAMS»(ref-168028-S29329301992004102800000).

Scheme 3

Scheme 4

Scheme 5

Scheme 6

Scheme 7

TEST B: UNUSUAL STARTER NOISE

1. Verify starter is installed properly. Ensure bolts are tight. Repair as necessary and check system for normal operation. If starter is mounted properly, go to next step.
2. Connect remote starter switch between positive battery terminal and starter motor relay terminal "S" (Yellow/Light Blue wire). (Scheme 3) Engage starter motor and verify noise is coming from starter motor. If noise is coming from starter motor, go to next step. If noise is not coming from starter motor, diagnose engine mechanical concern. See appropriate engine article in ENGINES.
3. Remove starter motor. See «STARTER MOTOR»(ref-168028-S41421407872004102800000) under REMOVAL & INSTALLATION. Inspect flywheel ring gear for wear or damage. If ring gear is okay, replace starter motor. If ring gear is worn or damaged, replace ring gear and inspect starter drive gear. If drive gear is also damaged, replace starter motor.

ON-VEHICLE TESTING

VOLTAGE DROP TEST

Note. Make all DVOM connections at component terminal rather than at cable or wire end.

Scheme 8

1. Ensure battery is fully charged. Disconnect inertia fuel shutoff switch to prevent vehicle from starting. Connect remote starter switch between starter solenoid terminal "S" and positive battery post. Connect positive DVOM lead to positive battery post, and negative lead to solenoid terminal "M". (Scheme 8)
2. Engage remote starter switch. If DVOM indicates.5 volt or less, go to «STARTER GROUND CIRCUIT TEST»(ref-168028-S11544866262004102800000). If DVOM indicates greater than.5 volt, go to next step.
3. Move negative DVOM lead to solenoid terminal "B". Engage remote starter switch. If DVOM indicates less than.5 volt, solenoid connections or contacts are bad. Clean solenoid terminals "B", "S" and "M". Repeat steps 1 - 3.
4. If DVOM still indicates more than.5 volt at terminal "M" and less than.5 volt at terminal "B", solenoid contacts are bad. Replace starter motor. See «STARTER MOTOR»(ref-168028-S41421407872004102800000) under REMOVAL & INSTALLATION. If DVOM indicates greater than.5 volt at terminal "B", clean cables and connections at solenoid.
5. If DVOM still indicates greater than.5 volt at terminal "B", check for poor positive battery cable connection or bad cable. Repair connection or replace battery cable as necessary.

STARTER GROUND CIRCUIT TEST

Note. Make all DVOM connections at component terminal rather than at cable or wire end.

1. Disconnect inertia fuel shutoff switch to prevent vehicle from starting. Connect remote starter switch between starter solenoid terminal "S" and positive battery post. (Scheme 9) Connect positive DVOM lead to starter housing, and negative lead to negative battery post.
2. Engage remote starter switch while observing DVOM. DVOM should indicate.2 volt or less. If DVOM indicates greater than.2 volt, clean negative cable connections at battery and engine.
3. If voltage drop is still excessive, repair or replace negative battery cable and/or engine ground cable as necessary. Repeat starter circuit test after repair to ensure problem has been corrected.
4. If battery and cables test okay and starter motor still cranks slowly or not at all, replace starter motor. See «STARTER MOTOR»(ref-168028-S41421407872004102800000) under REMOVAL & INSTALLATION.

Scheme 9