Diagnosis System

DESCRIPTION
1. 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 9141-2 as its communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.

Fig 1: Identifying DLC3 Connector Terminal

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TERMINAL NO. CONDITION DESCRIPTION

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 ohms
SG (5) - Body ground	Signal ground	Always	Below 1 ohms
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 ohms
CANH (6) - Battery positive	HIGH-level CAN bus line	Engine switch off	1 M ohms or higher
CANH (6) - CG (4)	HIGH-level CAN bus line	Engine switch off	3 k ohms or higher
CANL (14) - Battery positive	LOW-level CAN bus line	Engine switch off	1 M ohms or higher
CANL (14) - CG (4)	LOW-level CAN bus line	Engine switch off	3 k ohms 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.

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 in the tester itself. Consult the Service Department listed in the tester's operator's manual.

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.

Fig 2: Display - P/S Warning Light

TROUBLE AREA INDEX

Trouble Area	See Procedure
PS warning light circuit (Remains on)	PS Warning Light Remains ON
PS warning light circuit (Does not come on)	PS Warning Light Does Not Come ON