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Test E: Electronic Pressure Control Solenoid

  1. Electronic Diagnostics

    Ensure transaxle harness connector is in acceptable condition. Repair as necessary. Ensure transaxle harness connector is fully seated. Connect NGS tester or equivalent to DLC. Perform KEY ON ENGINE OFF (KOEO) SELF-TEST  until continuous memory codes have been displayed. Enter output test mode. Select ALL ON mode. Push START to turn outputs on. Push STOP to turn outputs off. If PCM enters output test mode, remain in output test mode and go to next step. If PCM will not enter output test mode, see SCAN TOOL UNABLE TO COMMUNICATE  under DIAGNOSIS & TESTING.

  2. Check Electrical Signal Operation

    Turn ignition switch to OFF position. Disconnect transaxle harness connector. Inspect condition of connector and repair as needed. Turn ignition switch to ON position. Using DVOM, connect positive lead to transaxle harness connector terminal No. 7 and negative lead to terminal No. 10. See Figure . While monitoring DVOM, press START and STOP to cycle EPC solenoid output on and off. If voltage changes at least .5 volt, go to step  5 . If voltage does not change as specified, go to next step.

  3. Check Continuity Of Solenoid Signal & VPWR Harness Circuits

    Ensure ignition switch is turned to OFF position. Disconnect PCM 104-pin connector, and inspect it for damaged terminals, corrosion and loose wires. Repair as necessary. Install breakout box, leaving PCM disconnected. Measure and record resistance between test pins No. 71 or 97 and transaxle harness connector terminal No. 7 on Continental and between test pin No. 71 and transaxle harness connector terminals No. 2 and 7 on Sable and Taurus. See Figure . Measure and record resistance between test pin No. 81 and transaxle harness connector terminal No. 10. If each resistance reading is less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, repair open circuit. Connect all components. Disconnect breakout box. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST  under DIAGNOSIS & TESTING.

  4. Check EPC Solenoid Harness For Shorts To Power & Ground

    Measure and record resistance between specified breakout box test pins. See EPC SOLENOID HARNESS SHORT CIRCUIT TEST  table. If each resistance reading is more than 10 k/ohms, go to next step. If any resistance reading is 10 k/ohms or less, repair short circuit. Connect all components. Disconnect breakout box. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST  under DIAGNOSIS & TESTING.
    EPC SOLENOID HARNESS SHORT CIRCUIT TEST (1)

    Breakout Box EPC Solenoid Pin No. Breakout Box Test Pins No.
    Continental
    81 71 & 97
    81 3, 25, 51, 77, 91, 103 & Ground
    Sable & Taurus
    81 71
    81 24, 25, 51, 76, 77, 91, 103 & Ground
    (1) Measure between breakout box test pins.

  5. EPC Solenoid Functional Test

    Connect PCM 104-pin connector. Disconnect transaxle harness connector. Connect transmission tester. Connect line pressure gauge. See HYDRAULIC PRESSURE TESTS under PERFORMANCE TESTS in FORD AX4N OVERHAUL article. Set Bench/Drive switch to DRIVE position. Set gear select switch to "1" position. Perform EPC solenoid function test. See transmission tester instructions. Observe line pressure on gauge while depressing EPC solenoid switch with KOER. EPC solenoid should activate (Green LED) and line pressure should drop when EPC solenoid switch is depressed. If EPC solenoid operates correctly (Green LED), replace PCM. Inspect PCM power relay. Repair as necessary. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST  under DIAGNOSIS & TESTING. If LED turns Red (shorted to VPWR) or if EPC solenoid does not activate LED (shorted to ground or open circuit), go to next step.

  6. Check Resistance Of EPC Solenoid

    Set Bench/Drive switch to BENCH position. Select OHMS CHECK. Connect ohmmeter to EPC solenoid jacks. If resistance reading is 3.23-5.50 ohms, go to next step. If resistance reading is not 3.23-5.50 ohms, go to step  8 .

  7. Check EPC Solenoid For Short To Ground

    Check continuity between BAT (-) jack and both EPC solenoid jacks on transmission tester. If continuity exists, go to next step. If continuity does not exist, see SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in FORD AX4N OVERHAUL article.

  8. Internal Electronic Diagnostics

    Drain transaxle fluid. Remove transaxle side cover. Inspect all internal harness connectors. Ensure internal harness connectors are fully connected and not damaged. Repair as needed. Install all components in reverse order of disassembly. Fill transaxle with fluid. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST  under DIAGNOSIS & TESTING. If internal harness connectors are okay, go to next step.

  9. Check Internal Transmission Harness Continuity

    Disconnect internal harness from EPC solenoid. Measure and record resistance between EPC solenoid jack on transmission tester and EPC solenoid connector Blue wire. Measure and record resistance between EPC solenoid VPWR jack on transmission tester and EPC solenoid connector (Green wire on Sable and Taurus, or White/Blue wire on Continental). If resistance readings are less than .5 ohm, go to next step. If any resistance reading is .5 ohm or more, replace internal harness. Go to step  11 .
    10. NOTE: Reading should be performed with a low current tester less than 200 milliamps.

  10. Check Internal Harness For Shorts To Ground
    Using transmission tester, check continuity between each EPC solenoid connector terminal and BAT (-) terminal of transmission tester. If continuity does not exist in either circuit, go to next step. If continuity exists in either circuit, replace internal harness. Go to next step.

  11. Check EPC Solenoid Resistance

    Using ohmmeter, check resistance between EPC solenoid terminals. If resistance reading is 3.23-5.50 ohms, go to next step. If resistance reading is not 3.23-5.50 ohms, replace EPC solenoid. Install all components in reverse order of disassembly. Fill transaxle with fluid. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST  under DIAGNOSIS & TESTING.
    12. NOTE: Reading should be performed with a low current tester less than 200 milliamps.

  12. Check EPC Solenoid For Short To Ground
    Using ohmmeter, check continuity between each EPC solenoid terminal and ground. If continuity exists, replace EPC solenoid. If continuity does not exist, install all components in reverse order of disassembly. Fill transaxle with fluid. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST  under DIAGNOSIS & TESTING. Attempt diagnosis by symptom. See SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in FORD AX4N OVERHAUL article.
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