If your display shows UNABLE TO CONNECT TO VEHICLE when you have connected the cable of the OBD II scan tool or hand-held tester to the DLC3, turned the ignition switch ON and operated the scan tool, there is a problem on the vehicle side or tool side. If communication is normal when the tool is connected to another vehicle, inspect the DLC3 on the original vehicle. Go to next step. If communication is still not possible 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.
Measure voltage between body ground and specified DLC3 terminals. See INSPECTING DATA LINK CONNECTOR NO. 3 CONDITION table. See Fig 1. The vehicle's ECM uses ISO 9141-2 for communication. The terminal arrangement of DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.

INSPECTING DATA LINK CONNECTOR NO. 3 CONDITION

Terminal No. (Connection)

Resistance

Condition

4 (Chassis Ground)

1 Ω Or Less

Always

5 (Signal Ground)

1 Ω Or Less

Always

7 (BUS Communication)

⁽¹⁾

During Transmission

16 (Battery Positive)

9-14 Volts

Always

⁽¹⁾	Pulse generation should exist during information transmission from engine control module (ECM).

Fig 1: Identifying Data Link Connector No. 3 Terminals

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Data Link Connector No. 3 Inspection