A worn vehicle speed sensor driven gear can cause the speedometer not to work. Replacing the worn out speed sensor should correct this concern.Google+
Car Problem Reports
Isuzu Rodeo Worn Speed Sensor Driven Gear May Cause Speedometer to Stop Working
Isuzu Rodeo Problem
Drive Train Affected: 4WD
Average Mileage: 150,250 mi (125,000 mi - 180,000 mi)
Visitor, 1994 Isuzu Rodeo, 144,000 mi
The speedometer stopped working.
Visitor, 1995 Isuzu Rodeo, 152,000 mi
The bearing for the nylon gear seized, causing the steel worm gear in the transmission to rub the nylon teeth off. It is an easy part to reach and replace, with minimal tools and experience. Hope this helps someone out there.
Visitor, 1999 Isuzu Rodeo, 4WD, 180,000 mi
Issue occurred when I was driving. The mechanic who worked on my vehicle said the unit looked like it had just exploded. It was a couple years ago now, so I'm struggling to remember what parts he did replace. He couldn't make the speedometer work still though, said that it was something with the speedometer and that by law I had to take it to an authorized speedometer testing shop. I never heard that one before, but I've been driving with an intermittently working speedometer for about 5 years now. It seems to work more often when it's cold out. I live in the Denver, CO area. In the summer my speedometer never works, but some days in the winter it does.
Speedometer sticks/stops at 15/20-mph.