• Tiny
  • duidanny
  • 1999 Toyota Camry

Electrical problem
1999 Toyota Camry 6 cyl Front Wheel Drive Automatic 65000 miles

The other day while driving down the freeway at approx 75 mph, my speedometer started frantically going up and down from 0-100 mph. At this same time my transmission felt as if it were slipping in and out, and the RPM would abruptly increase as the slippage occoured. My check engine light came on and I checked the OBD-II code. It read p0500 (VSS malfunction). Should I replace the sensor, or try to figure out if there is somthing else? Also where would that sensor be located on this car? Any held would be greatly appreciated. Thank you.

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have the same problem?
Monday, May 18th, 2009 AT 10:54 PM

1 Reply

  • Tiny
  • KHLow2008
  • Expert
  • 41,994 posts

Hi duidanny,

Item # 18 is the VSS.


Quite often this is the cause of the speedometer malfunctioning and replacement should solve the problem.


Circuit Description
VSS outputs a 4-pulse signal for every revolution of rotor shaft, which is driven by transaxle output shaft. Signal is sent to instrument cluster to operate speedometer. Instrument cluster then sends signal to ECM. Signal is used by ECM to determine vehicle speed. DTC is set if there is no VSS signal to ECM while vehicle is being driven and park/neutral switch is off. Possible causes are:

Defective vehicle speed sensor.
Vehicle speed sensor circuit is open or shorted.
Defective instrument cluster.
Defective ECM.

Diagnosis & Repair
1. Test drive vehicle and check operation of speedometer. If speedometer is operating correctly, go to next step.
2. Access ECM behind glove box. Raise and support one front wheel. Turn ignition on. Shift transaxle lever into Neutral. Using DVOM, backprobe ECM harness connector. On models with engine immobilizer system, measure voltage between ground and terminal No. 8 (Violet/White wire) at ECM harness connector E7. See Fig. 3 . On models without engine immobilizer system, measure voltage between ground and terminal No. 9 (Violet/White wire) at ECM harness connector E7. See Fig. 2 . On all models, observe voltage reading while rotating front wheel. Voltage should pulse between zero volts and 4.5-5.5 volts. If voltage is as specified, replace ECM. If voltage is not as specified, repair open or short in wiring between instrument cluster and ECM.



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Sunday, May 24th, 2009 AT 12:12 PM

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