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Home >> Ford >> 2000 >> Excursion 7.3 F, 4WD >> Repair and Diagnosis >> Transmission >> Transfer Case >> Four-Wheel Drive Systems (ESOF) - Excursion & F250-F550 Super Duty >> Diagnostic Tests >> Test A: Vehicle Does Not Shift Between 2WD & 4WD Modes Properly

Test A: Vehicle Does Not Shift Between 2WD & 4WD Modes Properly

  1. Check Ignition States; Monitor GEM PID IGN_GEM

    Turn ignition off. Connect NGS tester. Depress clutch pedal (if applicable) while turning ignition switch to START position. Monitor GEM PID Ignition Switch Status (IGN_GEM) while turning ignition switch through START, RUN, OFF and ACC positions. If PID values agree with ignition switch positions, go to next step. If values do not agree with ignition switch positions, diagnose ignition switch and circuits. See appropriate STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

  2. Retrieve DTCs

    Turn ignition off. Connect NGS tester. Retrieve and document continuous DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Clear continuous DTCs. Retrieve on-demand DTCs. See GEM ON-DEMAND SELF-TEST  under DIAGNOSIS & TESTING. If DTCs are retrieved, go to appropriate step(s). See DTC-TO-TEST STEP INDEX  table. If no DTCs are retrieved, go to next step.
    DTC-TO-TEST STEP INDEX

    DTC Go To Test Step
    P1812  4
    P1815  4
    P1820 (1)  12
    P1822  12
    P1828 (1)  19
    P1830  19
    P1865  35
    P1867  35
    (1) If these DTCs are retrieved together, go to step  26.

  3. Perform Electronic Shift Functional Test

    If electronic shift functional test was completed, go to next step. If test was not completed, see ELECTRONIC SHIFT FUNCTIONAL TEST  under DIAGNOSIS & TESTING.

  4. Monitor 4WD Mode Switch; Monitor GEM PID 4WD_SW

    Turn ignition on. Monitor GEM PID 4WD_SW while cycling 4WD mode switch through 2WD, 4X4 HIGH and 4X4 LOW. If GEM PID values agree with mode switch positions, go to step  10. If GEM PID values do not agree with mode switch positions, go to next step.

  5. Check 4WD Mode Switch (All Positions)

    Turn ignition off. Disconnect 4WD mode switch connector located in center of instrument panel. Measure resistance between terminals No. 2 and 3 (center terminals) on mode switch connector, while moving mode switch through each position. See MODE SWITCH RESISTANCE SPECIFICATIONS  table. If resistance is as specified, go to next step. If resistance is not as specified, replace mode switch. Clear DTCs and retest system.
    MODE SWITCH RESISTANCE SPECIFICATIONS

    Switch Position Ohms
    2WD 3700-4100
    4X4 HIGH 1050-1150
    4X4 LOW 340-380

  6. Check Circuit 465 (White/Light Blue Wire) For Open

    Turn ignition off. Disconnect GEM connector C240C (22-pin). Measure resistance of White/Light Blue wire between 4WD mode switch terminal No. 2 and GEM 22-pin connector terminal No. 4. See Figure. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in White/Light Blue wire. Clear DTCs and retest system.

  7. Check Circuit 780 (Dark Blue Wire) For Short To Voltage

    Turn ignition on. Check for voltage between ground and GEM connector C240C (22-pin) terminal No. 3 (Dark Blue wire). If voltage is present, repair short in Dark Blue wire. Clear DTCs and retest system. If no voltage is present, replace GEM. Clear DTC and retest system.

  8. Check Circuit 780 (Dark Blue Wire) For Open

    Measure resistance of Dark Blue wire between 4WD mode switch terminal No. 3 and GEM connector C240C (22-pin) terminal No. 3. See Figure. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue wire. Clear DTCs and retest system.

  9. Check Circuit 780 (Dark Blue Wire) For Short To Ground

    Measure resistance of Dark Blue wire between GEM connector C240C (22-pin) terminal No. 3 and ground. If resistance is more than 10 k/ohms, go to step  57. If resistance is 10 k/ohms or less, repair short to ground in Dark Blue wire. Clear DTCs and retest system.

  10. Check Voltage To Transfer Case Shift Motor

    Turn ignition off. Disconnect transfer case shift motor 2-pin connector. Turn ignition on. Measure voltage between ground and Orange wire at transfer case motor connector while triggering scan tool to set GEM active command CW/CCW to ON. Measure voltage between ground and Yellow wire at transfer case motor connector while triggering scan tool to set GEM active command CW/CCW to ON. If voltage is more than 10 volts on Yellow and Orange wires, go to step  56. If there is no voltage, or voltage is less than 10 volts on Orange and Yellow wires, go to step  31.

  11. Measure Voltage To Transfer Case Shift Motor

    Turn ignition on. Measure voltage between ground and Yellow wire at transfer case 2-pin connector. Measure voltage between ground and Orange wire at transfer case assembly connector. Make both measurements while triggering GEM active command CW/CCW to OFF. Voltages should be more than 10 volts. If voltage is more than 10 volts, go to step  56. If voltages are not more than 10 volts, go to step  31.

  12. Measure Voltage To Transfer Case Low-To-High Shift Relay Circuit 704 (Dark Green/Light Green Wire)

    Turn ignition off. Disconnect transfer case low-to-high shift relay connector. Shift relay is located in left side of engine compartment near battery junction box. Turn ignition on. Measure voltage between ground and both Dark Green/Light Green wires at transfer case low-to-high shift relay connector. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair Dark Green/Light Green wire(s). Clear DTCs and retest system.

  13. Check Transfer Case Low-To-High Shift Relay

    Turn ignition off. Disconnect low-to-high shift relay connector. Check for continuity between relay terminal No. 85 and each additional terminal. See Fig 1. Continuity should exist at terminal No. 86 only. If continuity exists at any other terminals, replace relay. Check for continuity between relay terminal No. 30 and each additional terminal. See Fig 1. Continuity should exist at terminal No. 87a only. If continuity exists at any other terminals, replace relay. Using 2 jumper wires, connect terminals No. 85 and 86 to battery positive and negative terminals. Check for continuity between terminals No. 30 and 87, and between terminals No. 30 and 87a. Continuity should exist between terminals No. 30 and 87 only. If continuity exists at any other terminals, replace relay. Clear DTCs and retest system. If relay is okay, go to next step.
    Fig 1: Identifying Transfer Case High-To-Low & Low-To-High Shift Relay Terminals
    G00006604Courtesy of FORD MOTOR CO.

  14. Check Circuit 782 (Brown/White Wire) For Short To Voltage

    Turn ignition off. Disconnect GEM connector C240C (22-pin). Turn ignition on. Measure voltage between ground and Brown/White wire at shift relay connector terminal No. 85. If voltage is not present, go to next step. If voltage is present, repair Brown/White wire for short to voltage. Clear DTCs and retest system.

  15. Check Circuit 782 (Brown/White Wire) For Open

    Turn ignition off. Measure resistance of Brown/White wire between shift relay connector terminal No. 85 and GEM 22-pin connector terminal No. 10. See Figure and Fig 1 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Brown/White wire. Clear DTCs and retest system.

  16. Check Circuit 782 (Brown/White Wire) For Short To Ground

    Measure resistance of Brown/White wire between shift relay connector terminal No. 85 and ground. See Fig 1. If resistance is more than 10 k/ohms, go to next step. If resistance is less than 10 k/ohms, repair short in Brown/White wire. Clear DTCs and retest system.

  17. Check Circuit 57 (Black Wire) For Open

    Measure resistance of Black wire between shift relay connector terminal No. 87a and ground. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Black wire. Clear DTCs and retest system.

  18. Check Circuit 777 (Yellow Wire) For Open

    Disconnect transfer case motor 2-pin connector. Measure resistance of Yellow wire between motor connector and shift relay connector terminal No. 30. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Yellow wire. Clear DTCs and retest system.

  19. Measure Voltage To Transfer Case High-To-Low Shift Relay Circuit 704 (Dark Green/Light Green Wire)

    Turn ignition off. Disconnect transfer case high-to-low shift relay connector. Turn ignition on. Measure voltage between ground and Dark Green/Light Green wire at transfer case high-to-low shift relay terminals No. 85 and 87. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair Dark Green/Light Green wire. Clear DTCs. Retest system.

  20. Check Transfer Case High-To-Low Shift Relay

    Turn ignition off. Disconnect high-to-low shift relay connector. Check for continuity between relay terminal No. 85 and each additional terminal. See Fig 1. Continuity should exist at terminal No. 86 only. If continuity exists at any other terminals, replace relay. Check for continuity between relay terminal No. 30 and each additional terminal. See Fig 1. Continuity should exist at terminal No. 87a only. If continuity exists at any other terminals, replace relay. Using 2 jumper wires, connect terminals No. 85 and 86 to battery positive and negative terminals. Check for continuity between terminals No. 30 and 87, and between terminals No. 30 and 87a. Continuity should exist between terminals No. 30 and 87 only. If continuity exists at any other terminal, replace relay. Clear DTCs and retest system. If relay is okay, go to next step.

  21. Check Circuit 781 (Orange/Light Blue Wire) For Short To Voltage

    Disconnect GEM connector C240C (22-pin). Turn ignition on. Measure voltage between transfer case high-to-low relay connector terminal No. 85 and ground. If voltage is not present, go to next step. If voltage is present, repair Orange/Light Blue wire for short to voltage. Clear DTCs and retest system.

  22. Check Circuit 781 (Orange/Light Blue Wire) For Open

    Turn ignition off. Measure resistance of Orange/Light Blue wire between high-to-low shift relay terminal No. 85 and GEM connector terminal No. 11. See Figure and Fig 1 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange/Light Blue wire. Clear DTCs and retest system.

  23. Check Circuit 781 (Orange/Light Blue Wire) For Short To Ground

    Measure resistance of Orange/Light Blue wire between high-to-low shift relay connector terminal No. 85 and ground. If resistance is more than 10 k/ohms, go to next step. If resistance is less than 10 k/ohms, repair short in Orange/Light Blue wire. Clear DTCs and retest system.

  24. Check Circuit 57 (Black Wire) For Open

    Measure resistance of Black wire between high-to-low shift relay connector terminal No. 87a and ground. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Black wire. Clear DTCs and retest system.

  25. Check Circuit 778 (Orange Wire) For Open

    Measure resistance of Orange wire between transfer case high-to-low relay connector terminal No. 30 and transfer case motor connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange wire. Clear DTCs and retest system.

  26. Check Fuses

    On Excursion, remove fuse No. 104 (30-amp) from power distribution box fuse. On "F" series, remove fuse No. 17 (30-amp) from power distribution box fuse. On all models, check fuse. If fuse is okay, go to next step. If fuse is blown, go to step  36.

  27. Measure Voltage At Fuses

    Measure voltage between ground and Dark Green/Light Green wire at input terminal of fuse No. 17 (except Excursion), or fuse No. 104 (Excursion). If voltage is more than 10 volts, repair Dark Green/Light Green wire. Clear DTCs and retest system. If voltage is less than 10 volts, repair fuse block as necessary. Clear DTCs and retest system.

  28. Check Circuit 704 (Dark Green/Light Green Wire) For Short To Ground

    Remove both shift relays. Measure resistance between ground and Dark Green/Light Green wire between both transfer case relay connector terminals No. 87. If resistance is less than 5 ohms, go to next step. If resistance 5 ohms or more, repair short in Dark Green/Light Green wire. Clear DTCs and retest system.

  29. Check Circuit 57 (Black Wire) For Open

    Measure resistance of Black wire between high-to-low shift relay connector terminal No. 87a and ground. If resistance is less than 5 ohms, go to next step. If resistance 5 ohms or more, repair open in Black wire. Clear DTCs and retest system.

  30. Check Circuits 777 (Yellow Wire) & 778 (Orange Wire) For Short To Ground

    Disconnect transfer case motor 2-pin connector. Measure resistance of Orange wire between motor connector and ground. Measure resistance of Yellow wire between motor connector and ground. If resistances are less than 5 ohms, repair wire(s). Clear DTC and retest system. If resistances are more than 5 ohms, go to step  57.

  31. Checking GEM PID'S

    Turn ignition off. Remove motor/encoder assembly from transfer case. Reconnect all disconnected connectors. Clear DTCs. Start engine and let idle. Apply parking brake. Depress brake pedal. Place transmission in Neutral and depress clutch pedal, if equipped. Using scan tool, monitor GEM PID VSS2, BOO, NTRLSW and CLTCHSW. If displays match vehicle conditions, go to next step. If displays do not match vehicle conditions, perform TEST C .

  32. Check Contact Plate Encoder Switch

    Using scan tool, monitor GEM PIDs PLATE_A, PLATE_B, PLATE_C and PLATE_D. Place 4WD mode switch in 2WD position. Record PIDs. Place 4WD mode switch in 4X4 HIGH position. Record PIDs. Place shift lever in "N" position. Depress brake pedal and clutch pedal, if equipped. Move mode switch to 4X4 LOW position. Record PIDs. See 4WD MODE SWITCH PID OUTPUT  table. If PIDs recorded match table, go to next step. If PIDs recorded do not match table, go to step  35.
    4WD MODE SWITCH PID OUTPUT

    Contact Plate 2WD 4X4 HIGH 4X4 LOW
    PLATE_A OPEN CLOSED CLOSED
    PLATE_B OPEN OPEN CLOSED
    PLATE_C CLOSED CLOSED OPEN
    PLATE_D OPEN OPEN OPEN

  33. Check Transfer Case

    Turn ignition off. Release parking brake. Using a wrench, manually shift transfer case sector shaft to full clockwise (2WD) position, while turning rear driveshaft. Apply parking brake. Attempt to rotate front drive shaft. If front drive shaft rotates, go to next step. If front drive shaft does not rotate, problem is in transfer case. See NV271 & NV273 TRANSFER CASE OVERHAUL article. Retest system.
    34. NOTE: Sector shaft has 4 detents. Full clockwise is 2WD, then 4X4 HIGH, then Neutral, and then 4X4 LOW.

  34. Check Sector Shaft Turning Effort
    Release parking brake. Using a torque wrench, manually shift transfer case sector shaft in a counterclockwise direction to 4X4 HIGH, while rotating rear drive shaft. If turning effort exceeds 33 ft. lbs. (45 N.m), problem is in transfer case. See NV271 & NV273 TRANSFER CASE OVERHAUL article. Retest system. If torque does not exceed 33 ft. lbs. (45 N.m), go to next step.

  35. Check Front Drive Shaft

    Apply parking brake. Attempt to rotate front drive shaft. If front drive shaft rotates, problem is in transfer case. See NV271 & NV273 TRANSFER CASE OVERHAUL article. Retest system. If front drive shaft does not rotate, replace motor/encoder assembly. Clear DTCs and retest system.

  36. Check Circuit 870 (Violet/Yellow Wire) Ground

    Disconnect motor/encoder connector. Measure resistance of Violet/Yellow wire between motor/encoder connector terminal No. 4 and ground. See Fig 2. If resistance is less than 5 ohms, go to step  38. If resistance is 5 ohms or more, go to next step.
    Fig 2: Identifying Motor/Encoder C285B Connector Terminals
    G00006642Courtesy of FORD MOTOR CO.

  37. Check Circuit 870 (Violet/Yellow Wire) For Open

    Disconnect GEM connector C240A (26-pin). Measure resistance of Violet/Yellow wire between motor/encoder connector terminal No. 4 and GEM connector terminal No. 9. If resistance is less than 5 ohms, go to step  58. If resistance is 5 ohms or more, repair Violet/Yellow wire. Clear DTCs and retest system.

  38. Check Circuit 976 (Orange Wire) For Voltage

    Turn ignition on. Measure voltage between ground and Orange wire at motor/encoder connector. If voltage is more than 9 volts on "F" series, or cycles between zero and 3 volts on Excursion, go to step  41. If voltage is not as specified, go to next step.

  39. Check Circuit 976 (Orange Wire) For Short To Ground

    Disconnect GEM connector C240C (22-pin). Measure resistance of Orange wire between motor/encoder connector terminal No. 2 and ground. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short in Orange wire. Clear DTCs and retest system.

  40. Check Circuit 976 (Orange Wire) For Open

    Measure resistance of Orange wire between motor/encoder connector terminal No. 2 and GEM connector C240C terminal No. 5. If resistance is less than 5 ohms, go to step  58. If resistance is 5 ohms or more, repair open in Orange wire. Clear DTCs and retest system.

  41. Check Contact Plate Switch "A"

    Reconnect GEM C240C connector. Using scan tool, monitor GEM PLATE_A. Connect jumper wire between ground and Violet/Yellow wire terminal on motor/encoder connector. Connect and reconnect ground while observing scan tool. If PID PLATE_A toggles between OPEN and CLOSED when ground is removed and applied, go to step  45. If PID does not toggle, go to next step.

  42. Check Circuit 771 (Violet/Yellow Wire) For Short To Voltage

    Measure voltage between ground and Violet/Yellow wire at motor/encoder connector terminal No. 5. If voltage is present, repair Violet/Yellow wire. Clear DTCs and retest system. If no voltage is present, go to next step.

  43. Check Circuit 771 (Violet/Yellow Wire) For Short To Ground

    Measure resistance between ground and Violet/Yellow wire at motor/encoder connector terminal No. 5. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short in Violet/Yellow wire. Clear DTCs and retest system.

  44. Check Circuit 771 (Violet/Yellow Wire) For Open

    Disconnect GEM C240C connector (22-pin). Measure resistance of Violet/Yellow wire between motor/encoder connector terminal No. 5 and GEM C240C connector terminal No. 15. If resistance is less than 5 ohms, go to step  58. If resistance is 5 ohms or more, repair open in Violet/Yellow wire. Clear DTCs and retest system.

  45. Check Contact Plate Switch "B"

    Using scan tool, monitor GEM PLATE_B. Connect jumper wire between Brown/White wire terminal on motor/encoder connector and ground. Connect and reconnect ground while observing scan tool. If PID PLATE_B toggles between OPEN and CLOSED when ground is removed and applied, go to step  49. If PID does not toggle, go to next step.

  46. Check Circuit 764 (Brown/White Wire) For Short To Voltage

    Measure voltage between ground and Brown/White wire at motor/encoder connector terminal No. 3. If voltage is present, repair Brown/White wire. Clear DTCs and retest system. If no voltage is present, go to next step.

  47. Check Circuit 764 (Brown/White Wire) For Short To Ground

    Measure resistance of Brown/White wire between motor/encoder connector terminal No. 3 and ground. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short in Brown/White wire. Clear DTCs and retest system.

  48. Check Circuit 764 (Brown/White Wire) For Open

    Disconnect GEM connector C240C (22-pin). Measure resistance of Brown/White wire between motor/encoder connector terminal No. 3 and GEM C240C connector terminal No. 17. If resistance is less than 5 ohms, go to step  58. If resistance is 5 ohms or more, repair open in Brown/White wire. Clear DTCs and retest system.

  49. Check Contact Plate Switch "C"

    Using scan tool, monitor GEM PLATE_C. Connect jumper wire between ground and White wire terminal at motor/encoder connector. Connect and reconnect ground while observing scan tool. If PID PLATE_C toggles between OPEN and CLOSED when ground is removed and applied, go to step  53. If PID does not toggle, go to next step.

  50. Check Circuit 770 (White Wire) For Short To Voltage

    Measure voltage between ground and White wire at motor/encoder connector terminal No. 6. If voltage is present, repair White wire. Clear DTCs and retest system. If no voltage is present, go to next step.

  51. Check Circuit 770 (White Wire) For Short To Ground

    Measure resistance of White wire between motor/encoder connector terminal No. 6 and ground. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short in White wire. Clear DTCs and retest system.

  52. Check Circuit 770 (White Wire) For Open

    Disconnect GEM C240C connector (22-pin). Measure resistance of White wire between motor/encoder connector terminal No. 6 and GEM C240C connector terminal No. 18. If resistance is less than 5 ohms, go to step  58. If resistance is 5 ohms or more, repair open in White wire. Clear DTCS and retest system.

  53. Check Contact Plate Switch "D"

    Using scan tool, monitor GEM PLATE_D. Connect jumper wire between Orange/White wire terminal on motor/encoder connector and ground. Connect and reconnect ground while observing scan tool. If PID PLATE_D toggles between OPEN and CLOSED when ground is removed and applied, replace motor/encoder assembly. Clear DTCs and retest system. If PID does not toggle, go to next step.

  54. Check Circuit 763 (Orange/White Wire) For Short To Voltage

    Measure voltage between ground and Orange/White wire at motor/encoder connector terminal No. 1. If voltage is present, repair Orange/White wire. Clear DTCs and retest system. If no voltage is present, go to next step.

  55. Check Circuit 763 (Orange/White Wire) For Short To Ground

    Measure resistance of Orange/White wire between motor/encoder connector terminal No. 1 and ground. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short in Orange/White wire. Clear DTCs and retest system.

  56. Check Circuit 763 (Orange/White Wire) For Open

    Disconnect GEM C240C connector (22-pin). Measure resistance of Orange/White wire between motor/encoder connector terminal No. 1 and GEM C240C connector terminal No. 16. If resistance is less than 5 ohms, go to step  58. If resistance is 5 ohms or more, repair open in Orange/White wire. Clear DTCs and retest system.

  57. Check Circuits 778 (Orange Wire) & 777 (Yellow Wire) For Short To Voltage

    Remove low-to-high and high-to-low shift relays. Measure voltage between ground and motor/encoder Yellow wire terminal. Measure voltage between ground and motor/encoder Orange wire terminal. If any voltage is present, repair wire(s). Clear DTCs and retest system. If no voltage is present, check both relays as follows: Check for continuity between relay terminal No. 85 and each additional terminal. See Fig 1. Continuity should exist at terminal No. 86 only. If continuity exists at any other terminals, replace relay. Check for continuity between relay terminal No. 30 and each additional terminal. See Fig 1. Continuity should exist at terminal No. 87a only. If continuity exists at any other terminals, replace relay. Using 2 jumper wires, connect terminals No. 85 and 86 to battery positive and negative terminals. Check for continuity between terminals No. 30 and 87, and between terminals No. 30 and 87a. Continuity should exist between terminals No. 30 and 87 only. If continuity exists at any other terminals, replace relay. Clear DTCs and retest system. If relays are okay, go to next step.

  58. Check For Correct Module Operation

    Check all connectors for corrosion, pushed out pins and proper seating. Repair as necessary. Connect any disconnected connectors. Operate vehicle and verify if problem is still present. If problem is still present, replace GEM. Clear DTCs and retest system. If problem is not present, system is operating normally. Clear DTCs and retest system.
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