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.
DTC P1640: Control Module Output Circuit: Description
The PCM contains an Output Driver Module (ODM) that controls the following devices:
- A/C relay
- 1-2 shift solenoid
- 2-3 shift solenoid
- Torque Converter Clutch (TCC) solenoid
The ODM provides grounded output control of these devices through separate control circuits. The ODM monitors the voltage level at each of the control circuits when the device is commanded ON or OFF. Each ODM output has an internal feedback circuit that connects to the PCM microprocessor. The PCM monitors voltage through the ignition 1 voltage circuit. Excessive voltage or current may cause damage to the PCM. If the ODM detects excessive current or voltage on an output control circuit, this DTC will set.
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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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