Diagnosis System

DESCRIPTION
1. Connecting the Techstream 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 Techstream to the DLC3 The Techstream enables you to clear the DTCs and check the freeze frame data and various forms of steering data.

CHECK DLC3

Check the DLC3.
The ECU uses ISO 15765-4 for communication. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.

Fig 1: Identifying DLC3

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TERMINAL DESCRIPTION CHART

Symbol (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⁽¹⁾

54 to 67 Ω

CANH (6) - CG (4)

HIGH-level CAN bus line

Engine switch off⁽¹⁾

200 Ω or higher

CANL (14)-CG (4)

LOW-level CAN bus line

Engine switch off⁽¹⁾

200 Ω or higher

CANH (6)-BAT (16)

HIGH-level CAN bus line

Engine switch off⁽¹⁾

6 kΩ or higher

CANL (14)-BAT (16)

LOW-level CAN bus line

Engine switch off⁽¹⁾

6 kΩ or higher

⁽¹⁾	Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the engine switch, any other switches or the doors.

HINT

Connect the Techstream to the DLC3, turn the engine switch on (IG), and attempt to use the Techstream. If the screen displays a communication error message, a problem exists on the vehicle side or the Techstream side

If communication is normal when connecting the Techstream to another vehicle, inspect the DLC3 on the original vehicle
If communication is still not possible when connecting the Techstream to another vehicle, the problem is probably in the Techstream itself Consult the Service Department listed in the Techstream operator's manual

P/S WARNING LIGHT
1. Check that the P/S warning light comes on when the engine switch is turned on (IG) and goes off in approximately 3 seconds.
2. If the warning light does not come on or remains on, inspect the P/S warning light circuit

P/S WARNING LIGHT REFERENCE CHART

Trouble Area	See Procedure
P/S warning light remains on	PS WARNING LIGHT REMAINS ON
P/S warning light does not come on	PS WARNING LIGHT DOES NOT COME ON

Fig 2: Identifying P/S Warning Light