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.
1989 Ford Probe GL, AutomaticFACTORY OEM SERVICE PROCEDURE
Measuring CES Resistance
- Checking NGS Operation - Remove vehicle battery to access NGS connector. Disconnect NGS. Set VOM on 200-ohm range. Measure resistance between wire terminals "R/GN" and "BK" at the NGS connector. If resistance is less than 5 ohms in gear and greater than 5 ohms in Neutral, repair open harness circuit between ECA and CES ("LG/BK" wire); between CES and NGS ("R/GN" wire); or in ground wire (BK wire) between NGS and ground. If resistance IS NOT less than 5 ohms in gear and greater than 5 ohms in Neutral, replace NGS.
- Check For Short to VPWR & KAPWR - Install breakout box and disconnect ECA. Set VOM on 20-volt scale. With KOEO, measure voltage between test pins No. 2 and 20 (ground), and between test pins No. 2 and 49. If any reading is greater than one volt, repair short in wiring harness to VPWR or KAPWR. If both readings are one volt or less, go to next step.
- Checking Voltage At ECA - Install breakout box, leaving ECA connected. Set DVOM on 20 volt scale. With KOEO and transmission in gear, measure voltage between test pins No. 2 and 20 (ground) at breakout box. If readings are greater than 10 volts with clutch pedal depressed and less than 0.5 volt with clutch pedal released, replace ECA. If voltage is not as specified, repair short to ground in wiring harness between ECA terminal No. "3D" and "R/GN" wire terminal at NGS connector.
Factory Service Tools
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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.