Diagnosis & Repair
WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.
- Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Turn ignition on. Turn scan tool on. Test drive vehicle and compare scan tool indicated speed with actual vehicle speed. If scan tool indicated speed matches actual vehicle speed, go to next step. If scan tool indicated speed does not match actual vehicle speed, replace ECM and retest system.
- Check speedometer operation. Repair speedometer circuit as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. If speedometer operation is okay, go to next step.
- Disconnect ECM E6 connector. Using an ohmmeter, measure resistance between terminals SP2+ and SP2- of the ECM connector. See Fig 1. If resistance is 560-680 ohms, replace ECM and retest system. If resistance is not 560-680 ohms, go to next step.
- Remove VSS from rear of transmission. Using an ohmmeter, measure resistance between VSS connector terminals. Resistance should be 560-680 ohms. Using a voltmeter set to AC voltage, measure voltage between VSS connector terminals. Place a magnet close to front of VSS and quickly remove (to generate a low voltage pulse). See Fig 2. If voltage pulse is not generated, replace VSS and retest. If voltage pulse is generated, check wiring harness between VSS and ECM. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Repair wiring as necessary.