Circuit Description

WARNING: This page is about a different car, the 2003 Lexus GX 470. However, it is still accessible from the selected car via links, so may be relevant.

Speed sensor for skid control computer assembly detects wheel speed and sends appropriate signals to skid control computer assembly. Skid control computer assembly converts these signals into a 4-pulse signal and outputs it to combination meter. After this signal is converted into a more precise rectangular waveform by waveform shaping circuit inside combination meter, it is then transmitted to ECM. ECM determines vehicle speed based on frequency of these pulse signals. DTCs will set when no speed sensor 1 signal is detected while ECM detects speed sensor 2 signal, vehicle speed is 6 MPH or more for 4 seconds, park/neutral position switch is off, transfer is any position except N and 4-pulse is generated 500 times (2 trip detection logic). Possible causes are:

Defective instrument cluster.
VSS circuit is open or shorted.
Defective vehicle speed sensor.
Defective ECM.
Defective skid control computer assembly.