Diagnostic Aids

Perform this test only when directed by QUICK TEST. This test is intended to diagnose:

Clutch Engage/Interlock Switch.
Neutral Drive/Gear Switch.
ECA.
Wiring harness circuits CES, CIS, NDS, NGS and SIG RTN.

Fig 1: Neutral Drive Input Circuit (M/T - Thunderbird 3.8L SC

Fig 2: Neutral Drive Input Circuit (A/T - Escort 1.9L, Probe 3.0L & Tracer 1.9L)

Fig 3: Neutral Drive Input Circuit (A/T - except Escort 1.9L, Probe 3.0L & Tracer 1.9L)

Fig 4: Neutral Drive Input Circuit (M/T - Escort 1.9L, Mustang, Probe 3.0L, Tempo, Topaz & Tracer)

TEST PIN NO. 30 (NDS/NGS) WIRE COLOR ID

Application	Wire Color
Cougar & Thunderbird	Red/Light Blue
Escort 1.9L & Tracer 1.9L	Brown/Yellow
Mark VII	White/Pink
Probe 3.0L	Red/Blue
All Others	Light Blue/Yellow

TEST PIN NO. 46 (SIG RTN) WIRE COLOR ID

Application	Wire Color
Cougar & Thunderbird	Black/White
Except Cougar & Thunderbird	Gray/Red

Fig 5: Neutral Drive Input Circuit (Taurus 3.0L SHO)

1) Code 67/522, 525, 527, 528 Or 634 System Identification Code 67/522, 525, 527 or 528 is a result of voltage being high at either pin No. 10 (A/C input) or 30 (neutral drive) while cranking engine or during KOEO SELF-TEST . Possible causes for these faults are:

A/C circuit shorted to power.
Clutch engage/interlock circuits open.
Neutral drive/gear switch open.
Faulty ECA.
Starter relay disconnected during self-test.

On 1.9L A/T and Probe 3.0L A/T, go to step 10). On all other A/T models, go to step 8). For 3.0L SHO M/T, go to step 7). On all other M/T models, go to step 2).

2) Check Neutral Gear/Clutch Input Turn ignition off. Turn A/C off (if equipped). 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 test pins No. 30 and 46 with transmission in Neutral and clutch pedal up. Measure resistance between test pins No. 30 and 46 with transmission in gear and clutch pedal down. If each resistance is less than 5 ohms, go to step 3). If resistance is 5 ohms or more, go to step 5).

3) Check Neutral Gear/Clutch Input Integrity Turn ignition off. Leave ECA disconnected from breakout box. Measure resistance between test pins No. 30 and 46 with transmission in any gear and clutch pedal up. See Fig 6 . If resistance is less than 5 ohms, go to CIRCUIT TEST KM, step 40) (models with A/C) or replace ECA and rerun QUICK TEST (all others). If resistance is 5 ohms or more, go to step 4).

Fig 6: Neutral Gear/Clutch Input Circuit

4) Check For Short To Ground Turn ignition off. Leave ECA disconnected from breakout box. Disconnect clutch engage switch. Measure resistance between test pins No. 30 and 46. If resistance is 10,000 ohms or more, go to procedures in CIRCUIT TEST KM, step 40) (models with A/C) or replace ECA and rerun QUICK TEST (all others). If resistance is less than 10,000 ohms, repair short circuit. Reconnect all components, and rerun QUICK TEST.

5) Check Neutral Gear/Clutch Engage Switch Turn ignition off. Leave ECA disconnected from breakout box. Locate neutral gear switch (on transmission) and clutch engage switch (at clutch pedal linkage). Disconnect wiring harness at both switches, and inspect connectors for pushed-back pins. Measure resistance across neutral gear switch terminals with transmission in Neutral. Measure resistance across clutch engage switch with clutch pedal down. If each resistance is 5 ohms or less, go to step 6). If resistance is more than 5 ohms, replace open switch. Reconnect all components, and rerun QUICK TEST .

6) Check Neutral Gear/Clutch Harness Turn ignition off. Leave ECA disconnected from breakout box. Disconnect neutral gear and clutch switches. Measure resistance between test pin No. 30 and neutral gear switch wiring harness connector. Measure resistance between test pin No. 30 and clutch engage switch harness connector. Measure resistance between test pin No. 46 and neutral gear switch wiring harness connector. Measure resistance between test pin No. 46 and clutch engage switch wiring harness connector. If any resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components and rerun QUICK TEST. If each resistance is less than 5 ohms, go to CIRCUIT TEST KM step 40) (models with A/C) or replace ECA and rerun QUICK TEST (all others).

7) Check Clutch Engage Switch 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. On 3.0L, measure resistance between test pins No. 30 and 46 at breakout box. If resistance is less than 5 ohms, go to CIRCUIT TEST KM step 40) (models with A/C) or replace ECA and rerun QUICK TEST (all others). If each resistance is 5 ohms or more, repair open circuit. Reconnect all components, and rerun QUICK TEST .

8) Check Neutral Drive Input 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. Ensure A/C is off (if equipped). Ensure transmission is in Neutral or Park. Turn ignition on. Measure voltage between test pin No. 30 and chassis ground. If voltage is less than 1.0 volt, go to CIRCUIT TEST KM step 40) (models with A/C) or replace ECA and rerun QUICK TEST (all others). If voltage is 1.0 volt or more, go to step 9).

9) Check Neutral Drive Switch Resistance Turn ignition off. Leave ECA disconnected from breakout box. Disconnect wiring harness from neutral drive switch. Measure resistance across switch terminals. If resistance is less than 5 ohms, repair open in NDS circuit. Reconnect all components, and rerun QUICK TEST . If resistance is 5 ohms or more, replace neutral drive switch. Reconnect all components, and rerun QUICK TEST .

10) Check Neutral Drive Input 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. Ensure transmission is in Neutral or Park. Disconnect 4EAT module 16-pin connector. Turn ignition on. Measure voltage between test pin No. 30 and chassis ground. If voltage is less than 1.0 volt, replace ECA. Reconnect all components, and rerun QUICK TEST . If voltage is 1.0 volt or more, go to step 11).

11) Check NDS Circuit Continuity Between ECA & 4EAT Module Turn ignition off. Leave ECA disconnected from breakout box. Disconnect 4EAT 16-pin connector. Set DVOM to 200-ohm scale. Measure resistance between test pin No. 30 at breakout box and NDS pin at 4EAT module wiring harness connector. If resistance is less than 5 ohms, fault is in 4EAT system. If resistance is 5 ohms or more, repair open circuit. Reconnect all components, and rerun QUICK TEST .

12) Check NDS Circuit For Short To Ground Or Closed Neutral Drive Switch Turn ignition off. Leave ECA disconnected from breakout box. Place transmission in Drive. Measure resistance between test pin No. 30 and test pins No. 40 and 60 at breakout box. If resistance is 10,000 ohms or more, NDS circuit is okay. Diagnose other possible causes. If resistance is less than 10,000 ohms, repair closed neutral drive switch or short circuit. Reconnect all components, and rerun QUICK TEST .