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.
On-Board Diagnostics System: Function
The on-board diagnostics system detects and stores in the form of a code a fault that has occurred in any of the following input and output signal systems.
| Rear vehicle speed sensor | Transfer duty solenoid | Low clutch timing solenoid |
|---|---|---|
| Front vehicle speed sensor | ATF temperature sensor | Torque converter turbine speed sensor |
| Throttle position sensor | Engine speed signal circuit | - |
| Shift solenoid 1 | Line pressure duty solenoid | - |
| Shift solenoid 2 | Intake manifold pressure signal circuit | - |
| 2-4 brake timing solenoid | Torque control signal circuit | - |
| Lock-up duty solenoid | 2-4 brake duty solenoid | - |
If a fault has been detected, the system tells the fault by causing the AT OIL TEMP warning light to operate as follows:
- Repeated flashing at 4 Hz frequency ...Errors such as battery trouble
- Repeated flashing at 2 Hz frequency ...No faults in the system
- Flashing at different intervals and frequencies ...Diagnostic trouble codes of corresponding faults
- Continued illumination of light ...Fault in inhibitor switch, idle switch, or wiring
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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