Overdrive light flashing & speedometer not working

[simone0414]

Haven't had a chance to check it out yet as just started doing it today & I am working all weekend but read on here it is probably a rear speed sensor. Speedometer bounches around periodically but most of the time does nothing. I guess checking the code should point me in the right direction. Tranny shifts normally.I pulled the dipstick & tranny fluid smells ok. My neighbor has a code reader that I can borrow but was wondering if they read tranny codes? Its just a regular one. Something tells me they don't.

One other thing that just started yesterday is we had a killer wind/rain storm here & water was leaking in on the drivers side up at the top of the windshield. Not sure if the windshield was leaking or around the top of the drivers door. First time I have noticed a leak. Pretty sure that water did not get near the speedo but yah never know.

Looking for some suggestions or confirmation that it probably is rear speed sensor.

[MtPaul401]

Same thing happened to me, no speedo, no tachs under 1200 rpm,OD light flashing. Rear diff speed sensor was bad, under $20 at NAPA. Quick and easy fix-it.

[simone0414]

My tach works fine. Hopefully that's all it is.

[Big_Red_Stroker]

in a OBS the that means dead trans! hope thats not the case with yours bud

[Laketrotter]

Side note, a couple company trucks we have had leaking windshield and the water drips right into the fuse box. After a while the boxes cooroded inside and causes starting and electrical problems.

[simone0414]

Originally Posted by Big_Red_Stroker

in a OBS the that means dead trans! hope thats not the case with yours bud

My tranny seems to be working fine. Not quite sure what your referring to?

[Big_Red_Stroker]

well if the Over Drive Off light is flashing on an OBS it means that its throwing a slip code. they just call it dead trans light

[no-tel-in]

not just a slip code, I believe it flashes when any trans related code is thrown

[Big_Red_Stroker]

very true sir

[simone0414]

Man you are scaring the crap out of me. How did we get from Rear diff sensor to tranny taking a dump? The tranny shifts as it always did. It does shift very firm I guess is the right term but has done this since I bought it. Shifts like it has a shift kit. But always shifts at approx. the same rpms. When you come on to her & she shifts into high gear it feels like you are getting a good kick in the pants. I was concerned about it when I bought the truck but the previous owner said he had it set up that way cause it is better for the tranny. I posted my concern on here a few months ago & was told the same thing so I never went any further with it. I have a tranny temp gauge & only one time it has gone about 100F & that was early last fall when I was towing my camper & it only went to about 110f for a about 30 seconds & then back down. Previous owner added a aftermarket tranny cooler as well.

On the way to work this morning the speedo was all over the place but on the way home it worked fine. Overdrive off light was still on though.


I am off for the next couple of days so I will check & see what code it is.