Lexus IS250 IS220d GSE20 ALE20 - POWER STEERING
ELECTRONIC POWER STEERING SYSTEM - DIAGNOSIS SYSTEM
| DESCRIPTION |
Connecting the intelligent tester to the vehicle and reading various data output from the power steering ECU assembly is the only difference between usual troubleshooting procedures and those for a vehicle with a diagnostic system.
The power steering ECU assembly records DTCs when the ECU detects a malfunction in the computer itself or in its circuits.
To check the DTCs, connect the intelligent tester to the DLC3. The intelligent tester enables you to erase the DTCs and check the freeze frame data and various forms of steering data.
| CHECK DLC3 |
Check the DLC3.
The power steering ECU assembly uses CAN and ISO 15765-4 communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.
| Symbols (Terminal No.) | Terminal Description | Condition | Specified Condition |
| SIL (7) - SG (5) | Bus "+" line | During communication | Pulse generation |
| CG (4) - Body ground | Chassis ground | Always | Below 1 Ω |
| SG (5) - Body ground | Signal ground | Always | Below 1 Ω |
| BAT (16) - Body ground | Battery positive | Always | 11 to 14 V |
| CANH (6) - CANL (14) | HIGH-level CAN bus line | Engine switch off | 54 to 67 Ω |
| CANH (6) - Battery positive | HIGH-level CAN bus line | Engine switch off | 1 MΩ or higher |
| CANH (6) - CG (4) | HIGH-level CAN bus line | Engine switch off | 3 kΩ or higher |
| CANL (14) - Battery positive | LOW-level CAN bus line | Engine switch off | 1 MΩ or higher |
| CANL (14) - CG (4) | LOW-level CAN bus line | Engine switch off | 3 kΩ or higher |
- HINT:
- Connect the intelligent tester cable to the DLC3, turn the engine switch on (IG), and attempt to use the tester. If the screen displays a communication error message, a problem exists on the vehicle side or the tester side.
| P/S WARNING LIGHT |
Check that the PS warning light comes on when the engine switch is turned on (IG) and goes off in approximately 3 seconds.
If the warning light does not come on or remains on, inspect the PS warning light circuit.
| Trouble Area | See Procedure |
| PS warning light circuit (Remains on) | |
| PS warning light circuit (Does not come on) |