The speedometer and odometer in a 1990 Chevy Astro Van may not work due to a malfunctioning vehicle speed sensor (VSS), which sends speed data to the dashboard. Additionally, issues such as a broken speedometer cable, faulty instrument cluster, or electrical problems can also cause these gauges to fail. Inspecting these components can help diagnose and resolve the issue.
If the speedometer is not working but the odometer is, I would suspect the dash cluster is at fault. If both speedometer and odometer are not working I would suspect the speed sensor on the transmission is at fault.
unhook it from the speedometer head and unhook it from the tranny and take it out.
Need to figure out what's wrong with them, first.
If both the odometer and the speedometer do not work it may be the speed sensor in the transmission is bad. If only the odometer does not work it is probably a bad cluster.
There is a separate motor that runs the odometer. It is not running for some reasson. TAke it to a speedo shop.
PROBABLY one of the little tiny itty bitty gears has stripped
If both the speedometer and odometer stopped working it is probably the speed sensor in the transmission gone bad. If only the speedometer quit you may have to replace the dash cluster with a reconditioned unit.
Jet Accu Speed Speedometer calibrator. It adjusts your speedometer for bigger tires or gear change. Only works on automatic transmissions.
Starting the motor.
If both the speedometer and the odometer do not work I would suspect the VSS (Vehicle Speed Sensor) located on the tail shaft of the transmission is at fault. If only the speedometer doesn't work it's probably a problem with the dash cluster.
The power off button.
If both the speedometer and the odometer work on and off, I would blame the vehicle speed sensor. If only the speedometer is acting up, I would blame the cluster.