Why would a 95 Dodge Neon speedometer work only intermittently?

Answer 1

Check the wires to the speed sensor and the sensor itself.

Resolder connections on instrument panel.

http://www.neons.org/modules/news/article.php?storyid=18

My 96 Neon's speedometer, temp and fuel gauges were intermittent. Had taken the instrument cluster apart a couple times, nothing obvious. Saw an online posting somewhere about cold solder joints on the circuit board where the gauges plug in. Took the cluster apart again, hit all those sockets with my soldering iron, applying ample fresh solder. Put it back together and haven't had a problem since. That was almost a year ago. If you're not comfortable with a soldering iron and circuit boards, find a friend who is.

If this is good, then check for oil based fluid on the computer module plugs. Racked my brains on this one. Traced all wiring for sensor, started to replace the speed sensor, but when comparing replacement sensor with original one, noticed these sensors have high resistive circuitry and my original was fine. Put original sensor back on car and traced cabling back to computer module. Have to remove the entire computer module to fully unplug those two 60 pin plugs. Upon removing the plug closes to the outside wall, found an oily base fluid inside. Cleaned out fluid with a little bit of engine cleaner spray and blew it dry with compressor. Speedometer works great now. Called local Dodge dealer to ask if computer module contain any fluid inside, they stated no. I initially thought some mechanic had sabotaged by putting fluid in this plug, however approximately 6 months later intermittent speedometer started up again. Remove this plug and sure enough, more fluid. I am starting to think the local Dodge dealer did not know what he was talking about. Cleaned up a second time......speedometer is working perfect once again. When fluid builds up in this plug, it becomes conductive across the speedometers high resistive circuitry.