Diagnosis System
- DESCRIPTION
- DIAGNOSTIC SYSTEM
When troubleshooting a vehicle with a diagnostic system, the only difference from the usual troubleshooting procedure is connecting the hand-held tester to the vehicle and reading various data output from the vehicle's transmission control ECU assy.
The transmission control ECU assy records DTCs when the computer detects a malfunction in the computer itself or in its circuits.
To check the DTCs, connect the hand-held tester to the DLC3 on the vehicle. The hand-held tester enables you to erase the DTCs, activate the several actuators and check freeze frame data and data list.
- Check the DLC3.
The transmission control ECU assy follows the CAN and ISO 9141-2 communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.
- DIAGNOSTIC SYSTEM
| Symbols (Terminals No.) | Terminal Description | Condition | Specified Condition |
|---|---|---|---|
| SIL(7) - SG(5) | Bus "+" line | During communication | Pulse generation |
| CG(4) - Bodyground | Chassis ground | Always | Below 1Ω |
| SG(5) - Bodyground | Signal ground | Always | Below 1Ω |
| BAT(16) - Bodyground | Battery positive | Always | 11 to 14V |
| CANH(6) -CANL(14) | HIGH-level CAN bus line | Power switch off | 54 to 67 Ω |
| CANH(6) - Battery positive | HIGH-level CAN bus line | Power switch off | 1 MΩ or higher |
| CANH(6) - CG(4) | HIGH-level CAN bus line | Power switch off | 3 KΩ or higher |
| CANL(14) - Battery positive | LOW-level CAN bus line | Power switch off | 1 MΩ or higher |
| CANL(14) - CG(4) | LOW-level CAN bus line | Power switch off | 3 KΩ or higher |
HINT:
If the display shows "UNABLE TO CONNECT TO VEHICLE" after connecting the hand-held tester cable to the DLC3 and turning the power switch on (IG), there is a problem with either the vehicle or tester.
- If communication is normal when connecting the tester to another vehicle, inspect the DLC3 on the original vehicle.
- If communication is still not possible when connecting the tester to another vehicle, the problem is probably on the tester itself, so consult the Service Department listed in the tester's operator's manual.