Connect scan tester to DLC3 connector. See Figure. Turn ignition on. Turn scan tester on. Using scan tester read MAP sensor value. If reading is same as atmospheric pressure, go to next step. If reading in not same as atmospheric pressure, inspect component and ECM connections. Problem is intermittent.

Fig 1: Connecting Scan Tester Locating DLC No. 3 (DLC3)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Access ECM behind glove box. Turn ignition on. Backprobing ECM connector, measure voltage between terminals No. 18 (Light Green/Red wire) and No. 16 (Brown wire) at ECM E7 connector. See Fig 2. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest.
Backprobing ECM connector, measure voltage between terminals No. 4 (Pink wire) and No. 16 (Brown wire) at ECM E7 connector. If voltage is 3.3-3.9 volts, replace ECM and retest. If voltage is not 3.3-3.9 volts, go to next step.
Check for an open or short circuit between MAP sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, replace MAP sensor and retest.

Fig 2: Engine Control Module (ECM) Connector Terminal ID

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

Diagnosis & Repair