Diagnostic Aids

Perform this test only when directed by QUICK TEST. To prevent replacing good components, check following non-EEC areas for 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 the following items:

• Wiring Harness Circuits M/CCC, CCO, CCS, EPC, SS3/4, SS1, SS2, SS3, SIG RTN, EPC PWR And VPWR
• Faulty ECA

Fig 1: AOD-E Solenoid Circuits

1. 1) Output State Check  Code 621, 622, 626, 627, 629, 641 or 652 indicates shift solenoid did not respond to ECA command. Following are possible causes of faults: Faulty Manual Lever Position (MLP) Sensor, Circuit Open Or Grounded or 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. Perform KOEO SELF-TEST  until continuous memory test is complete. When test is complete, DVOM will read less than 1.0 volt to indicate ECA has entered OUTPUT STATE CHECK. Depress and release throttle. If voltage increases, remain in OUTPUT STATE CHECK, and go to next step. If voltage does not increase, depress throttle to WOT and release. If STO voltage goes high, go to next step. If STO voltage does not go high, leave test equipment connected. Check and repair throttle linkage as necessary, or disconnect cruise control (if equipped). Go to next step.

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 by 0.5 volt or more, fault is in transmission. If voltage output does not change by 0.5 volt or more, go to step 3).
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 EEC-IV Breakout Box (T83L-50-EEC-IV), 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 step 4).
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 any 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. Code 99/624 indicates failure of EPC circuit. Code 98/625 indicates EPC driver failure. Following are possible causes of faults: Faulty Solenoid, Circuit Open Or Groundedor Faulty ECA.
6. 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 step 11).
7. 11) Check Solenoid Resistance  Turn ignition off. Leave transmission wiring harness connector disconnected. Measure resistance between VPWR and EPC PWR terminals and suspect component terminal at transmission wiring harness connector. If resistance is not 3-7 ohms, fault is in transmission. If resistance is 3-7 ohms, go to step 12).
8. 12) Check Solenoid Signal & VPWR Circuit Continuity  Turn ignition off. Disconnect 60-pin ECA connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving ECA disconnected. Measure resistance between breakout box test pins No. 37 and 57 and VPWR/EPC PWR terminal at transmission wiring harness connector. Measure resistance between test pin No. 32 at breakout box and EPC solenoid terminal at transmission wiring harness connector. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST  . If resistance is less than 5 ohms, go to step 13).
9. 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. 38 and pins No. 37/57 at breakout box. Measure resistance between test pin No. 38 and test pins No. 40/60 and 46 at breakout box. If any resistance is less than 10 k/ohms, repair short circuit, and repeat QUICK TEST  . If each resistance is 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 13) to step 20). No test procedures have been omitted.
10. 20) Check Solenoid Resistance  KOEO Code 621 (SS1), 622 (SS2) or 643 (CCC) indicates failure in shift solenoid circuit. Following are possible causes of faults: Faulty Shift Solenoid, Circuit Open Or Grounded or Faulty ECA.
11. Turn ignition off. Disconnect transmission wiring harness connector. Measure resistance between suspect shift solenoid at transmission wiring harness connector and chassis ground. If resistance is 13-17 ohms, go to step 21). If resistance is not 13-17 ohms, go to step 22).
12. 21) Check Shift Solenoid For Short To Power  Turn ignition off. Disconnect transmission wiring harness connector. Disconnect 60-pin ECA connector. Inspect terminals and repair if damaged. Turn ignition on. Measure voltage between suspect shift solenoid at transmission wiring harness connector and chassis ground. If voltage is more than 0.5 volt, repair short to power, and repeat QUICK TEST  . If voltage is 0.5 volt or less, go to step 22).
13. 22) Check Shift Solenoid For Short To Ground  Turn ignition off. Leave transmission wiring harness connector disconnected. Measure resistance between suspect shift solenoid at transmission wiring harness connector and chassis ground. Measure resistance between suspect shift solenoid and all other circuits at transmission wiring harness connector. If any resistance is less than 10 k/ohms, repair short circuit, and repeat QUICK TEST  . If every resistance is 10 k/ohms or more, go to step 23).
14. 23) Check Shift Solenoid Circuit Continuity  Turn ignition off. Leave transmission wiring harness connector disconnected. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving ECA disconnected. Measure resistance between suspect shift solenoid at breakout box and suspect shift solenoid terminal at transmission wiring harness connector. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST  . If resistance is less than 5 ohms, go to step 24).
15. 24) Check Shift Solenoid For Short To Power In Transmission  Turn ignition off. Leave ECA disconnected from breakout box. Reconnect transmission wiring harness connector. Measure voltage between test pin No. 60 and suspect shift solenoid terminal at breakout box. If voltage is 0.5 volt or more, replace or repair solenoid short to power. If voltage is less than 0.5 volt, replace ECA, and repeat QUICK TEST  .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 24) to step 30). No test procedures have been omitted.
16. 30) Continuous Memory Codes 621, 622 & 643  Continuous Memory Code 621 (SS1), 622 (SS2) or 643 (CCC) indicates a failure was detected in shift solenoid circuit during last 80 warm-up cycles. Following are possible causes of faults: Faulty Shift Solenoid or Circuit Open Or Grounded.
17. Turn ignition off. Check shift solenoid circuit between ECA and transmission. Repair or replace as necessary. If circuits are okay, go to step 31).
18. 31) Check For Intermittent Short Or Open  Turn ignition off. Disconnect 60-pin ECA connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving ECA disconnected. Turn ignition on. Connect test light between test pin No. 37 and suspect shift solenoid terminal at breakout box. Test light should be at partial brightness. Observe test light while wiggling and bending shift solenoid circuit between transmission and ECA. An open or short to power will be indicated by light going off. A short to ground will be indicated by light getting brighter. Repeat procedure for all solenoids. If fault is indicated, isolate and repair as necessary. If no fault is indicated, go to step 32).
19. 32) Check For Intermittent Short To Ground  Turn ignition off. Leave ECA disconnected from breakout box. Disconnect transmission wiring harness connector. Turn ignition on. Connect test light between test pin No. 37 and suspect shift solenoid terminal at breakout box. Test light should be off. Observe test light while wiggling and bending shift solenoid circuit between transmission and ECA. A short to ground will be indicated by light turning on. Repeat procedure for all solenoids. If fault is indicated, isolate and repair as necessary. If no fault is indicated, problem is intermittent and cannot be duplicated at this time.