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.
Circuit Test Description
Turning on A/C supplies battery voltage to circuit No. 59 A/C compressor clutch, and to terminal "B8" of ECM connector to increase idle air rate and maintain idle speed.
The ECM does not control the A/C compressor clutch; therefore, if A/C does not function, service A/C system.
If A/C is operating properly and idle speed dips too low when A/C compressor turns on, or flares too high when A/C compressor turns off, check for an open circuit No. 59 to ECM. If circuit is okay, it is a faulty ECM connector terminal "B8" or ECM.
NO RELATED
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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.