Using An Ammeter

WARNING: This page is about a different car, the 2003 Lexus RX 300 and 2002 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect the connector from the power window master switch.
Connect the positive (+) lead from the ammeter to terminal No. 1 on the wiring harness side connector and the negative (-) lead to the negative (-) terminal of the battery. See Fig 1.
Connect the positive (+) lead from the battery to terminal No. 15 on the wiring harness side connector.
As the window goes down, check that the current flow is approximately 7 amps.

NOTE: The PTC opens some 4-90 seconds after the window stops going down, so that check must be made before the PTC operates.

Check that the current increases up to approximately 14.5 amps or more when the window stops going down. If the operation is as specified, replace the master switch. See DOOR TRIM PANEL (FRONT) under REMOVAL & INSTALLATION under POWER DOOR LOCKS & LIFTGATE RELEASE article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT.

Fig 1: Inspecting One-Touch System Using Ammeter