Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD1985BRONCO 5.8 G, STANDARD, TODREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 38 (3.0L EFI EEC IV TESTING)CIRCUIT TESTSTEST M - NEUTRAL A/C SWITCH INPUT
1985 Ford Bronco 5.8 G, Standard, TOD
Test M - Neutral A/C Switch Input
1985 Ford Bronco 5.8 G, Standard, TODSECTION Test M - Neutral A/C Switch Input
WARNING: This page is about a different car, the 1986 Ford Aerostar. However, it is still accessible from the selected car via links, so may be relevant.
- Code 67 Displayed. If code 67 is displayed, go to step 5 .
- Turn key off and wait 10 seconds. Make sure heater control is in "OFF" position and that transmission is in Neutral or Park. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA. Turn key on, leaving engine off. Set DVOM on 20-volt scale and measure voltage between test pin 30 and chassis ground. If reading is less than 1.0 volt, go to step 4 . If reading is 1.0 volt or higher, go to next step.
- Turn key off and wait 10 seconds. Leave breakout box installed and ECA connected. Locate neutral drive switch and disconnect harness at switch. Set DVOM on 200-ohm scale and measure resistance across switch. If reading is less than 5 ohms, repair open in neutral drive switch circuit. Repeat QUICK TEST . If reading is 5 ohms or more, replace neutral drive switch and repeat QUICK TEST .
- Install breakout box and connect ECA. Turn key on, leaving engine off. Set DVOM on 20-volt scale, and turn A/C control switch off. Measure voltage between test pin 10 and chassis ground. If reading is 1.0 volt or more, repair short to power in A/C clutch circuit. Repeat QUICK TEST . If reading is less than 1.0 volt, replace ECA and repeat QUICK TEST .
- Turn key off and wait 10 seconds. Make sure that A/C is off, if equipped. Ensure that transmission is in Neutral and that clutch is released. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA. With DVOM on 200-ohm scale, measure resistance between test pins 30 and 46. If reading is less than 5 ohms, go to step 4 ). If reading is 5 ohms or more, go to next step.
- Turn key off. With breakout box and ECA connected, set DVOM on 200-ohm scale. Locate neutral switch (on transmission) and clutch switch (under dash). Disconnect wiring harness from both switches. Measure resistance across each switch. If reading at both switches is less than 5 ohms, go to step 4 . If reading at either or both switches is 5 ohms or more, replace defective switch(es). Connect harness and repeat QUICK TEST .
- Turn key off and wait 10 seconds. Verify that A/C switch is off, if equipped. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA. Set DVOM on 20-volt scale. Measure resistance between test pin 30 and neutral input circuit at SELF-TEST connector. If reading is less than 5 ohms, go to step 4 . If reading is ohms or more, repair open in neutral input circuit. Repeat QUICK TEST .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.