92 B250 Dodge Van, 318 engine, 4 speed auto trans. Speedometer reads about 10 to 15 mph too low. I have not changed my tires. I replaced the speed sensor on the transmission and that did not change anything. I have no warning light or codes present. I have noticed that the van wants to go very fast in reverse - have to apply breaks to control the speed while backing. Occasionally, I get a jerking motion (hesitation then sudden forward shift) as I go forward from a stop. I have replaced the transmission fluid and filter and adjusted the bands - but this did not help. Any ideas would be appreciated. Thanks!
Dodgevanman
08-10-2005, 06:53 AM
There's still a pinion gear that runs the speed sensor...you should have seen it when you replaced the speed sensor. These come in various diameters and a certain amount of teeth. Your local dealer should be able to tell you what one you need if you give them your rear gear ratio and your wheel/tire diameter total.
jcole
08-11-2005, 10:17 PM
Have you even heard of the pinion gear failing?
Dodgevanman
08-12-2005, 06:38 AM
Since they're made of plastic, the only failure I could think of is that the teeth would break or strip causing the speedo not to work at all.
jcole
08-12-2005, 09:05 AM
Thanks, this speedometer reads 10 to 15 mph low. I'm at a loss for what could cause a partial loss of signal.
Dodgevanman
08-12-2005, 11:37 AM
when did this start happening?
jcole
08-14-2005, 01:44 AM
It started after I replaced a water pump a couple months ago.
Dodgevanman
08-14-2005, 07:49 PM
Hmmm replacing a water pump shouldn't have any bearing on the speed sensor...it could just be coincidental. The speedo itself could be "out of whack" and needs recalibration.
