Engine Immobiliser System: Pre-Check

DIAGNOSIS SYSTEM

Description
The ECM controls the immobiliser function of the vehicle. The data of the immobiliser or Diagnostic Trouble Code (DTC) can be read in the Data Link Connector 3 (DLC3) of the vehicle. When a trouble occurs in the immobiliser, Malfunction Indicator Lamp (MIL) does not come on but DTC inspection is performed.

Fig 1: Connecting Hand-Hold Tester To DLC3
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Therefore when there seems to be a trouble with immobiliser, use the hand-held tester or SST to check and troubleshoot it.

Check the DLC3.

The vehicle's ECM uses ISO 9141-2 for communication. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.

Fig 2: Identifying DLC3 Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TESTING DLC3 CONNECTOR

Tester Connection	Condition	Specified Condition
7 (Bus + Line) - 5 (Signal Ground)	During Communication	Pulse Generation
4 (Chassis Ground) - Body Ground	Always	1 Ω Or Less
5 (Signal Ground) - Body Ground	Always	1 Ω Or Less
16 (B+) - Body Ground	Always	9 - 14 V

NOTE: If the display shows UNABLE TO CONNECT TO VEHICLE when you have connected the cable of the hand-held tester or the OBD II scan tool to the DLC3, turned the ignition switch ON and operated the handheld tester or OBD II scan tool, there is a problem on the vehicle side or tool side.

If the communication is normal when the tool is connected to another vehicle, inspect the DLC3 of the original vehicle.
If the communication is still impossible when the tool is connected to another vehicle, the problem is probably in the tool itself, so consult the Service Department listed in the tool's instruction manual.

INSPECT DIAGNOSIS
1. Using the hand-held tester or the OBD II scan tool, check the DTC.
  NOTE: Hand-held tester or OBD II scan tool only:
  When the diagnosis system is switched from the normal mode to the check mode, all the DTCs and freeze frame data recorded in the normal mode will be erased. So before switching the modes, always check the DTCs and freeze frame data, and write them down.
  1. Prepare the hand-held tester or the OBD II scan tool.
  2. Connect the hand-held tester or the OBD II scan tool to the DLC3 under the instrument panel lower pad.
  3. Turn the ignition switch ON and push the hand-held tester or the OBD II scan tool switch ON.
  4. Use the hand-held tester or the OBD II scan tool to check the DTCs and freeze frame data and write them down. (For operating instructions, see the hand-held tester or the OBD II scan tool instruction book.)
  5. See DIAGNOSTIC TROUBLE CODE CHART to confirm the details of the DTCs.
2. The following operations will erase the DTCs and freeze frame data.
  1. Operating the hand-held tester or the OBD II scan tool to erase the codes. (See the hand-held tester or the OBD II scan tool instruction book for operating instructions).
  2. Disconnecting the battery terminals or the EFI fuse.