If scan tester displays UNABLE TO CONNECT TO VEHICLE when scan tester is connected, try scan tester on another vehicle. If scan tester operates on another vehicle, proceed to step 2). If scan tester does not operate on another vehicle, problem is probably with scan tester.
Note location of DLC No. 3 (Fig. Figure) and its terminals (Fig. Fig 1). Ensure voltage and resistance are correct at specified terminals when checking between terminal on DLC No. 3 and body ground. See DLC NO . 3 VOLTAGE & RESISTANCE SPECIFICATIONS table. If voltage and resistance are not as specified, check wiring circuit. See the WIRING DIAGRAMS article.

NOTE: Terminal No. 2 on DLC No. 3 provides pulse generation during information transmission from Engine Control Module (ECM).

DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS

Fig 1: Identifying DLC No. 3 Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

DLC No. 3 Inspection