VSS No. 1 Circuit (Speedometer Does Not Operate)
WARNING:
On LS400, removing cover from rear of instrument cluster will expose screw heads "a"-"f" and connectors "K", "P" and "Q". See Fig 2. These screw heads and connectors are part of the cold cathode tubes in the cluster. When power is supplied to cluster, DO NOT
touch these connectors and screw heads because they are electrically charged with high AC voltage.
- Check VSS No. 1. See VEHICLE SPEED SENSOR (VSS) NO . 1. If VSS No. 1 is okay, remove instrument cluster. Remove cover and power source unit from back of instrument cluster for access to printed circuit. Check for continuity between the following speedometer terminals of printed circuit. See Figure.
- "A" and b9
- "B" and a7
- "C" and b11
- If there is no continuity, replace printed circuit. If there is continuity, install power source unit. DO NOT install rear cover. Reconnect instrument cluster connectors.
- Raise and support vehicle with rear wheels off of ground. Turn ignition on. At power source unit connector "R", connect voltmeter positive lead to terminal No. 10 and negative lead to terminal No. 12. See Fig 1 and Fig 2. Rotate drive shaft.
- If voltage alternates between about zero and 9 or more volts for each revolution of drive shaft, replace speedometer. If voltage does not alternate between about zero and 9 or more volts, replace power source unit.