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.
Basic Troubleshooting: Notes
AW30-40LS transmission, with Transmission Control Module (TCM), differs from the Mechanical - Hydraulic control type transmissions. Accordingly, its troubleshooting procedure differs also.
Before troubleshooting an TCM, first determine whether the problem is electrical or mechanical. To do this, just refer to Fig 1 the basic troubleshooting flowchart .
If the cause is already known, using the basic troubleshooting chart below along with the troubleshooting chart should speed the procedure.
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.