HELP! My Speedometer Pegs Out Instantly!

[soundguy787]

I just bought a 99 Ranger, and as soon as you start rolling the speedometer shoots up to pegged out (what should be 140ish?) probably around 5 mph. Thus the transmission is also having problems where it very quickly gets into top gear and doesn't wanna down shift. I have replaced the Rear wheel abs sensor already and that did not make a difference. The odometer is also following suite, so its racking up massive amounts of mileage to drive it anywhere. Has anyone ever seen this before? Please help, I'm starting to pull my hair out.

BTW: 3.0L Automatic 2WD

 

[Mark_88]

Well, not sure if it's just a speedo issue, but my Tempo did some really whacky things with the gauges...just before the Alternator blew up...

If nothing else pans out to correct it, check that your alternator is working properly. Apparently they are three phase (maybe different now) and the middle phase on mine somehow disappeared...if that makes any sense...

 

[alaskan155]

check the tranny tailhousing for a vss sensor to, and check the wiring from the vss sensor to the front of the truck betting the sensor is grounding out, then after the vss(es, if 2) are checked the next thing to check is the gem module which distributes the vss signal throughout the truck,

 

[budro]

Yeap check the VSS our Taurus did that one day going down the interstate at 75 looked down for a sec and boom it pegged it then went to zero and back to 75. Then the car acted like it didnt have power steering. Pulled over cut it off and it didnt do it again. Checked the codes and VSS sensor code.

Check the codes if it is a VSS it should post the code.

 

[soundguy787]

I went to the shop and they confirmed that the only speed sensor on my truck is the one in the differential. They said there is a plug where the other style would go. They unhooked the sensor so the transmission would shift better, but no idea as to why it is doing what it is doing. According to the odometer and some calculations the VSS is sending a signal about 10x what it actually is. They hooked it up to the computer and its actually the vss or the computer sending that signal and not a bad speedometer.

 

[RumpRanger98]

its most likely the VSS. I had an auto tranny act real crazy when that went bad.

 

[UrbanRedneckKid]

I had a customer bring in a Mustang with that issue. It hit fuel-cut at 45mph, and the speedo was pegged.

Turned out to have the wrong VSS in it.

'''it had a Cobra trans and dash swap, had the sensor for the car, needed the one for the dash.

 

[hazrd]

I know this is an old thread but my 02 4x4 ranger is doing something similar. I cant find anything.on the VSS location on it. Are there 2 in the transfer case?

 

[Earl43P]

Look on top of the rear axle pumpkin, it's the only electrical plug there. The VSS is held in with one 10mm bolt on a fork. All the resistance to removing it after that is crud and an oring.