jumpy speedo

[2stroke]

why does my speedo get real jumpy? any where from 5 to 20 mph jumps. all the time while moving. is it a bad cable?

[Rebel Ram]

Check the plug at the trans. The pins get loose where they slip into the sockets. Then they make intermitant contact along with pulse signal from the sender causes spazed speedo. Anyway, thats what was wrong with mine.

[CAJUN 93]

mine did that for about a week before my speedo sensor fell off . check the connections by the drivers side rear of the trans. make sure the sensor is tight to the adapter. our trucks dont have a cable.

[2stroke]

i dont think that i have one of those sensors. my speedo cable goes into the gear reduction thingy at the t- case.

[CAJUN 93]

yep, i didn't realize you had a 90. may be a broken cable. hold one end and try spinning the other. sometimes a broken cable will cause the speedo to jump at slow speeds, but not at high because the friction causes the broken ends to grip.

best way i've found to check a speedo is with a drill. undo the cable at the trans and spin with drill and have someone monitor the speedo. if it operates ok, the problem is in the trans. if not undo the cable at the speedo and spin speedo with drill (usually requires a homegrown adapter) and see if it operates ok. if so, problems the cable, if not, problems the speedo head. it also helps to have a variable speed drill

[dpuckett]

Both my 90 and 91 had electronic sensors. Of course, they were 2wds. There are a lot of little differences like that from year to year.

I'd check the gears in the tranny and speedo adaptors. ALso, if your ratio adaptor has a grease fitting on it, stick some grease in there.

DP

[90firstgen]

My 90 is also an electronic sender. i could be way wrong but I thought only the 89's had cables.... I'm also 2WD

[dpuckett]

BGilbert's 90 donor rig had a cable, and the turnover at 100K odometer. Weird.