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.
Monitor Description
The transmission ECU and the ECM perform two-way communications with each other via the Controller Area Network (CAN). The transmission ECU sends signals to the ECM concerning required engine rpm, required engine torques, warning indicators in the combination meter, DTCs, and other data. The ECM sends signals to the transmission ECU concerning engine rpm, opening angles of the throttle valve, temperature of intake air, temperature of engine coolant, engine torques, and other data.
If the transmission ECU cannot communicate with the ECM, the transmission ECU will conclude that there is a malfunction in the CAN system, illuminate the MIL and set a DTC.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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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