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.
Transmission Control Module (TCM) or Powertrain Control Module (PCM)
- Ignition Voltage
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Displays 0.0-25.5 V. This parameter is the system voltage measured by the TCM or PCM at the TCM or PCM ignition input when the ignition switch is in the RUN position.
- IMS (Transmission Internal Mode Switch) Range
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Displays Park, Park/Reverse, Reverse, Reverse/Neutral, Neutral, Neutral/Drive 4, Drive 4, Drive 4/Drive 3, Drive 3, Drive 3/Drive 2, Drive 2, Drive 2/Drive 1, Drive 1, Invalid or Open. The IMS Range display represents a decoded status of the four inputs from the IMS. This range includes all possible in-between gear states as well as the detent gear states. The combination of IMS inputs to the TCM or PCM are used by the TCM or PCM in order to determine what position the manual valve is in at any time.
- IMS (Internal Mode Switch) States A/B/C/P
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Displays LOW or HI for the state of each of the four inputs from the IMS. LOW displayed indicates a low voltage signal (0 volts) being monitored at the TCM/PCM. HI displayed indicates a high voltage signal (B+) being monitored at the PCM.
- TCC Brake Switch
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Displays ON when the brake pedal is depressed and the brake switch contacts close. Displays OFF when the brake pedal is released and the brake switch contacts open.
Use the Manual With the Right Hardware
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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.
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