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Test E: Electronic Pressure Control Solenoid: Testing

  1. Electronic Diagnostics

    Ensure transmission harness connector is fully seated, terminals are engaged in connector and in good condition. Repair as necessary. Install NGS tester to DLC. Perform KEY-ON-ENGINE-OFF (KOEO) SELF-TEST  until continuous memory code(s) have been displayed. See QUICK TEST  under DIAGNOSIS & TESTING. Select OUTPUT TEST MODE (OTM), select ALL ON MODE and press START to activate outputs. If vehicle enters OTM, remain in OTM and go to next step. If vehicle will not enter OTM, see SCAN TOOL UNABLE TO COMMUNICATE  under DIAGNOSIS & TESTING.

  2. Check Electrical Signal Operation

    Disconnect transmission 12-pin harness connector. Inspect condition of connector. Repair as needed. Using DVOM, connect positive lead to transmission harness connector EPC VPWR terminal No. 12 (Red/Yellow wire), and connect negative lead to EPC signal terminal No. 11 (White/Yellow wire). See Figure. Press START then STOP on NGS tester to cycle solenoid output. If voltage changes to battery voltage, go to step  5. If voltage is not as specified, go to next step.

  3. Check Continuity Of Solenoid Signal & VPWR Harness Circuit

    Turn ignition switch to OFF position. Disconnect PCM 104-pin harness 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 breakout box VPWR pins No. 71 and 97 and transmission harness connector terminal No. 11 (White/Yellow wire). See Figure. Measure and record resistance between breakout box PCM Signal pin No. 81 and transmission harness connector terminal No 11 (White/Yellow wire). If each resistance is less than 5 ohms, go to next step. If any resistance is 5 ohms or more, repair open circuit(s). Disconnect breakout box. Connect all components. Erase all DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST .

  4. Check Harness For Short To Power Or Ground

    Measure and record resistance between breakout box pin No. 81 and breakout box pins No. 71 and 97. See Figure. Measure and record resistance between breakout box pin No. 81 and breakout box pins No. 24, 51, 76, 77, 91 and 103. If each resistance is more than 10 k/ohms, go to next step. If any resistance is 10 k/ohms or less, repair short circuit(s). Disconnect breakout box. Connect all components. Erase all DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST .

  5. EPC Functional Test

    Reconnect PCM harness connector. Disconnect transmission 12-pin harness connector. Connect transmission tester to transmission connector. Connect line pressure gauge. See LINE PRESSURE TESTS under PERFORMANCE TESTS in FORD 4R100 OVERHAUL article. Set Bench/Drive switch to DRIVE MODE. Set Gear Select switch on transmission tester to "1" position. Perform EPC function test. See transmission tester instructions. With engine running, observe line pressure on gauge while depressing EPC switch. EPC solenoid should activate (LED Green) and line pressure should drop when EPC switch is depressed. If solenoid operates correctly, replace PCM. Connect all components. Erase all DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST . If solenoid does not operate, LED does not light (solenoid shorted to ground or open circuit), or indicates short to battery voltage (LED Red), go to next step.

  6. Check Resistance Of Solenoid

    Ensure tester power is off. Set Bench/Drive switch to BENCH MODE. Set Gear Select switch on transmission tester to OHMS CHECK position. Connect ohmmeter negative lead to VPWR terminal, and positive lead to EPC terminal. Measure and record resistance. Resistance should be 3-5 ohms. If resistance is within specifications, go to next step. If resistance is not within specifications, replace solenoid body assembly. Connect all components. Erase all DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST .
    7. NOTE: The following test should be performed with a digital ohmmeter or low current tester (less than 200 milliamps).

  7. Check Solenoid For Short To Ground
    Check continuity between transmission tester BAT (-) terminal and EPC and EPC VPWR terminals on transmission tester. If continuity exists, replace solenoid body assembly. Connect all components. Erase all DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST . If continuity does not exist, diagnose problem by symptom. See SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING.
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