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.
4WD Control Unit
Remove radio and remove 4WD control unit. Disconnect control unit harness connector. Backprobe harness connector. Check voltage between each individual terminal and ground terminal No. 8 (Black wire). See Fig 1 and 4WD CONTROL UNIT PIN VOLTAGE CHART . If after all tests have been completed system is not operating properly, substitute 4WD control unit with known-good unit and retest.
| Terminal ID (Wire Color) | Function/Description | Voltage Value (DC Volts Unless Otherwise Specified) |
|---|---|---|
| 1 (Yellow/Blue) | HI/LO Detection Switch | KOEO - 9-11 Volts With Transfer In "N" |
| 1 (Yellow/Blue) | HI/LO Detection Switch | KOEO - 0 Volt In "4HLc" Or "4LLc" |
| 2 (Blue/Orange) | 4WD Operation Detection Switch | KOEO - 9-11 Volts In "2H" |
| 2 (Blue/Orange) | 4WD Operation Detection Switch | KOEO - 0 Volt "4H" |
| 3 (Blue/Yellow) | Ignition Switch (IG2) | Ignition Off - 0 Volt |
| 3 (Blue/Yellow) | Ignition Switch (IG2) | Ignition On - Battery Voltage |
| 4 (Blue/Green) | Center Differential Lock Indicator Light | KOEO - Battery Voltage With Transfer In "4H" |
| 4 (Blue/Green) | Center Differential Lock Indicator Light | KOEO - 0-1.5 Volts With Transfer In "4HLc" |
| 5 (Blue/White) | Center Differential Lock Detection Switch | KOEO - 9-11 Volts With Transfer In "4H" |
| 5 (Blue/White) | Center Differential Lock Detection Switch | KOEO - 0 Volt With Transfer In "4HLc" |
| 6 (Yellow/Green) | Free Wheel Engage Switch | KOEO - 9-11 Volts With Vehicle in 2WD |
| 6 (Yellow/Green) | Free Wheel Engage Switch | KOEO - 0 Volt With Vehicle in 4WD |
| 7 (Yellow/Blue) | Center Differential Lock Operation Detection Switch | KOEO - 9-11 Volts With Transfer In "4H" |
| 7 (Yellow/Blue) | Center Differential Lock Operation Detection Switch | KOEO - 0 Volt With Transfer In "4HLc" |
| 9 (Yellow/Black) | Rear Wheel Indicator Light | KOEO - 0 Volt With Transfer In "N" |
| 9 (Yellow/Black) | Rear Wheel Indicator Light | KOEO - 9-11 Volts In "4HLc" Or "4LLc" |
| 10 (Yellow/Red) | Front Wheel Indicator Light | KOEO - 0 Volt With Vehicle In 2WD |
| 10 (Yellow/Red) | Front Wheel Indicator Light | KOEO - 9-11 Volts With Vehicle In 4WD |
NO RELATED
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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.