Diagnostic Aids

Perform this test only when directed by QUICK TEST. To prevent replacing good components, be aware following non-EEC-IV areas may be at fault:

• Engine base condition (cam timing, valves rings, etc.).
• Brakes.
• Transmission fluid, friction elements and cooling.

This test is not intended to diagnose transmission. This test is intended to diagnose:

• Wiring harness circuits CCO, SS 3/4, and VPWR.
• Faulty ECA.

1. 1) Output State Check  Code 629 indicates shift solenoid did not respond to ECA command. Possible causes for these faults are:
   • Circuit open or grounded.
   • Faulty ECA.

   To enter Output State Check, use only VOM or DVOM. DO NOT use scan tester. Turn ignition off. Disconnect cruise control servo wiring harness connector. Connect DVOM negative lead to STO terminal at self-test connector. Connect positive lead to positive battery terminal. Install a jumper wire between SIG RTN terminal at self-test connector and STI terminal. See Fig 1 . Perform KOEO SELF-TEST  until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete to indicate ECA has entered Output State Check. Depress and release throttle. If voltage increases, remain in Output State Check and go to step 2). If voltage does not increase, depress throttle to WOT and release. If STO voltage goes high, go to step 2). If STO voltage does not go high, leave test equipment connected and check throttle linkage for sticking or binding. Repair or lubricate linkage as necessary. If throttle linkage is okay, replace Throttle Position (TP) sensor and rerun QUICK TEST  procedure.

   Fig 1: Identifying A4LD Transmission Connector

   Courtesy of FORD MOTOR CO.
2. 2) Check Solenoid Electrical Condition  Turn ignition off. Disconnect transmission wiring harness connector. Inspect terminals, and repair if damaged. Connect VOM or DVOM positive test lead to solenoid VPWR connector. Connect negative test lead to appropriate solenoid terminal at transmission wiring harness connector. Cycle solenoid output on and off by depressing and releasing throttle 3-5 times. If voltage output changes 0.5 volt or more, fault is in transmission. If voltage output does not change 0.5 volt or more, go to next step.
3. 3) Check Continuity Between Solenoid & VPWR Circuits  Turn ignition off. Leave transmission wiring harness disconnected. Disconnect 60-pin ECA connector. Inspect terminals, and repair if damaged. Install Breakout Box (BOB), leaving ECA disconnected. Measure resistance between ECA output signal terminal at ECA wiring harness connector and output signal terminal at transmission wiring harness connector. Measure resistance between breakout box test pins No. 37 and 57 and VPWR terminal at transmission wiring harness connector. If either resistance is less than 5 ohms, repair open circuit and repeat QUICK TEST  . If both resistances are 5 ohms or more, go to next step.
4. 4) Check Solenoid Circuit For Short To Power Or Ground  Turn ignition off. Leave ECA disconnected from breakout box. Leave transmission wiring harness disconnected. Measure resistance between ECA output signal test pin and test pins No. 37 and 57 at breakout box. Measure resistance between ECA output signal test pin and pins No. 40, 46 and 60 at breakout box. Measure resistance between ECA output signal test pin and chassis ground. If either resistance is less than 10 k/ohms, repair short circuit and repeat QUICK TEST  . If all resistances are 10 k/ohms or more, replace ECA and repeat QUICK TEST.
   NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 10). No test procedures have been omitted.
5. 10) Check VPWR To Solenoid  Code 86/566 or 89/629 indicates shift solenoid did not respond to ECA command. Possible causes for these faults are:
   • Faulty solenoid.
   • Circuit open or grounded.
   • Faulty ECA.

Turn ignition off. Disconnect transmission wiring harness connector. Turn ignition on. Measure resistance between VPWR and EPC PWR terminal at transmission wiring harness connector and chassis ground. If voltage is less than 10.5 volts, repair open circuit and repeat QUICK TEST  . If voltage is 10.5 volts or more, go to next step.

11) Check Solenoid Resistance  Turn ignition off. Leave transmission wiring harness connector disconnected. Measure resistance between VPWR and suspect solenoid terminal at transmission wiring harness connector. If resistance is not 26-40 ohms, replace solenoid. If resistance is 26-40 ohms, go to next step.

12) Check Solenoid Signal & VPWR Circuit Continuity  Turn ignition off. Disconnect 60-pin ECA connector. Inspect terminals, and repair if damaged. Install BOB, leaving ECA disconnected. Measure resistance between breakout box test pins No. 37 and 57 and VPWR terminal at transmission wiring harness connector. Measure resistance between CCO or SS 3/4 test pin at breakout box and solenoid terminal at transmission wiring harness connector. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST  . If resistance is more than 5 ohms, go to next step.

13) Check Circuit For Short To Power Or Ground  Turn ignition off. Leave ECA disconnected from breakout box. Leave transmission wiring harness connector disconnected. Measure resistance between test pin No. 52 or 53 and pins No. 37 and 57 at breakout box. Measure resistance between test pin No. 52 or 53 and pins No. 40, 46 and 60 at breakout box. If either resistance is less than 10 k/ohms, repair short circuit and repeat QUICK TEST  . If all resistances are 10 k/ohms or more, replace ECA and repeat QUICK TEST.