Diagnostic Aids

Perform this test when instructed by QUICK TEST or if directed by other test procedures. This test is only intended to diagnose:

• AM1 or AM2 solenoid valve assembly.
• Wiring harness circuits (AM1, AM2 and VPWR).
• Vacuum supply.
• ECA.

To prevent replacement of good components, be aware following non-EEC related areas may be at fault:

• Thermactor air system drive belt, air pump and valve.
• Blocked or restricted thermactor air passages in engine.

Application	Wire Color
2.3L HSC, Cougar 5.0L & Thunderbird 5.0L	White/Red

Application	Wire Color
Mark VII 5.0L	Light Green/Black
Mustang 5.0L	White/Light Green

Application	Wire Color
Mark VII 5.0L	White/Red
Mustang 5.0L	White/Yellow

1) Codes 44/311, 45/312, 46/313 & 94/314  Code 44/311 or 94/314 indicates thermactor system is inoperative. Code 45/312 indicates thermactor air is incorrectly routed. Code 46/313 indicates thermactor air is not by-passed when directed. Possible causes for these faults are:

• Vacuum hoses leaking, blocked or kinked.
• Air pump or diverter valve inoperative.
• Air Management (AM) solenoid defective or blocked.

Check for correct vacuum hose routing to AM1/AM2 solenoids and by-pass diverter valve. See Vehicle Emission Control Information (VECI) label. Check for kinked or blocked vacuum hoses. Check for kinked or blocked air hoses. Check for disconnected vacuum hoses. If faults are detected, repair as necessary and repeat QUICK TEST  . If no faults are detected and Code 44/311 or 94/314 is present, go to step 4).If Code 46/313 is present, go to step 3). If Code 45/312 is present, go to step 2).

2) Attempt To Eliminate Code 45/312  Disconnect and plug vacuum hose at diverter valve. Turn ignition off. Repeat KOER SELF-TEST  , and record codes. If Code 45/312 is present, EEC-IV system is okay. Inspect diverter valve and check valve for faults. If Code 45/312 is not present, go to step 4).

3) Attempt To Eliminate Code 46/313  Disconnect and plug vacuum hose at by-pass valve. Turn ignition off. Repeat KOER SELF-TEST  , and record codes. If Code 46/313 is present, EEC-IV system is okay. Check by-pass valve for problem. If Code 46/313 is not present, go to step 4).

4) Output Check  Enter OUTPUT STATE CHECK. See ADDITIONAL SYSTEM FUNCTION. Use only a VOM or DVOM for this step. DO NOT use scan tester. Turn ignition off. Disconnect cruise control servo (if equipped). With DVOM on 20-volt scale, connect DVOM negative lead to STO terminal at self-test connector. Connect positive lead to positive battery terminal. Using jumper wire, connect STI to SIG RTN at self-test connector. See Figure -Figure in CIRCUIT TEST B. Perform KOEO SELF-TEST until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete. Depress and release throttle. If voltage increases, remain in OUTPUT STATE CHECK and go to step 5). If voltage does not increase, depress throttle to WOT and release. If STO voltage does not go high, go to CIRCUIT TEST QC.

5) Check Solenoid Electrical Operation  Set DVOM on 20-volt scale. Disconnect AM solenoids. Connect DVOM positive lead to VPWR terminal and negative lead to AM1 terminal at AM1 solenoid wiring harness connector. While observing DVOM, depress and release throttle several times to cycle output on and off. Repeat test for AM2 solenoid. Connect DVOM positive lead to VPWR terminal and negative test lead to AM2 terminal on AM2 solenoid wiring harness connector. Cycle AM2 solenoid on and off. If either solenoid does not cycle more than 0.5 volt, remove jumper and go to step 9). If both solenoids cycle more than 0.5 volt, stay in OUTPUT STATE CHECK, reconnect solenoids and go to step 6).

6) Check Solenoids For Vacuum Cycling  Connect vacuum pump to AM1 solenoid vacuum supply port. Connect vacuum gauge to output port. Maintain vacuum at source while depressing and releasing throttle to cycle output on and off. Observe vacuum gauge. Repeat for AM2 solenoid. If either output does not cycle on and off, replace solenoid assembly and repeat QUICK TEST  . If both outputs cycle on and off, exit OUTPUT STATE CHECK and go to step 7).

7) Check Solenoids For Internal Vacuum Leaks  Connect a vacuum pump to AM1 solenoid supply port. Connect a vacuum gauge to AM1 solenoid output port. Apply 15 in. Hg vacuum and observe gauge. Repeat test for AM2 solenoid. If vacuum gauge reading holds vacuum for each solenoid, check vacuum source for blockage and leakage from manifold to solenoids and control valves. If vacuum source is okay, inspect thermactor air tube and air passages in cylinder head for carbon blockage. Repeat QUICK TEST  . If vacuum gauge does not hold vacuum, replace solenoid assembly and repeat QUICK TEST.

8) Codes 81/553 & 82/552: Check VPWR Circuit Voltage  Codes81/553 and 82/552 indicate voltage output for thermactor air solenoid did not change when activated. Possible causes for this fault are:

• Shorted or open circuits.
• Solenoid resistance out of range.
• Faulty ECA.

Disconnect both solenoid connectors. Turn ignition on. Measure voltage between VPWR terminal of wiring harness connector and battery ground for both solenoids. If either voltage reading is less than 10.5 volts, repair wiring harness open circuit. Connect solenoid connectors, and repeat QUICK TEST  . If both readings are 10.5 volts or more, go to step 9).

9) Measure Solenoid Resistance  Turn ignition off. Set DVOM on 200-ohm scale. Disconnect AM1 and AM2 solenoid connectors. Measure resistance of both solenoids. If either reading is not 50-100 ohms, replace solenoid assembly and repeat QUICK TEST  . If both readings are 50-100 ohms, go to step 10).

10) Check Circuit Continuity  Turn ignition off. Disconnect ECA 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 51 (No. 38 on Mustang 5.0L or No. 31 on 2.3L HSC, Cougar 5.0L and Thunderbird 5.0L) and AM1 terminal at wiring harness connector. Measure resistance between test pin No. 11 (No. 32 on Mustang 5.0L) and AM2 terminal at wiring harness connector. If either reading is 5 ohms or more, repair open circuit and repeat QUICK TEST  . If both readings are less than 5 ohms, go to step 11).

11) Check For Short To Ground  Turn ignition off. Measure resistance between breakout box test pin No. 51 (No. 38 on Mustang 5.0L or 31 on 2.3L HSC, Cougar 5.0L and Thunderbird 5.0L) and pins No. 40, 46 and 60. Also measure resistance between test pin No. 11 (No. 32 on Mustang 5.0L) and test pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short to ground and repeat QUICK TEST  . If all readings are 10,000 ohms or more, go to step 12).

12) Check For Shorts To Power Circuit  Turn ignition off. Measure resistance between breakout box pin No. 51 (No. 38 on Mustang 5.0L or No. 31 on 2.3L HSC, Cougar 5.0L and Thunderbird 5.0L) and test pins No. 37 and 57. Also measure resistance between test pin No. 11 (No. 32 on Mustang 5.0L) and test pins No. 37 and 57. If any resistance is less than 10,000 ohms, repair short to power and repeat QUICK TEST  . If code is present again, replace ECA. If all resistances are 10,000 ohms or more, replace ECA, remove breakout box, reconnect AM1/AM2 solenoid and repeat QUICK TEST.