My 2001 Toyota 4runner has, on random occurrences, has had the traction alarm go off for no reason while driving. Just recently it went off and then Dashboard lights started coming on. I currently have the Parking brake light, TRAC OFF, VSC TRAC, ABS, and then just yesterday the Check Engine light.

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Last night, I noticed that the Speedometer is just sitting at 0 even when driving. The car drives fine. No loss of power or anything, so I am guessing this is a broken sensor. I don't have any OBD codes yet, but I get my scanner soon so I'll add them.

Any idea's as to what it wrong? What steps should I take to diagnose it? Is it safe to drive for the time being?

2 Answers 2


On this model vehicle speed is determined by the Wheel Speed Sensors. They send a signal to the Vehicle Skid Control module which is relayed to the Instrument Cluster and drives the speedometer gauge. It's then converted to a 5 or 12v square wave and sent to the Engine Control module to provide the ECM with vehicle speed.

You can pull the code from the ECM, likely a P0500. But unless your scantool can talk to the VSC module it probably won't help you any. You can flash the ABS/VSC codes by jumping E1 and Tc in the DLC 1 connector or Tc and CG in the DLC 3 connector.

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You should start by doing a visual inspection of the WSS wiring harnesses and scoping the sensor output. If the output is OK to the VSC module then you need to confirm signal to the ICM and from there to the ECM.


For the sake of completeness, here are additional details as to how I further diagnosed and fixed the problem. From the field service manual, you can find a diagram showing where the DLC 1 mentioned by Ben above is,

Parts Location @ DI-17

Connecting my OBD Scanner to the DLC3, gave the codes,

You can find a description of this on page DI-103 titled "DTC P0500 Vehicle Speed Sensor Malfunction"

The select pages needed for this problem can be seen here

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