I recently purchased A 1999 F-150, with a week or so of owning it the transmission started to shutter and I could see that it was only going to go down hill from there. I decided to convert the truck to 5SPD tranny, after doing so the speedometer will not work. Now heres a little more of the story, along with doing a 5spd swap I also did an axle swap, The transmisson and axles both came out of the same truck. so I cant see th gear ratio for the speedo sensor being a problem yet the speedo will not register the speed of the truck correctly and only goes up to 20mph when on the freeway. Im stumped! checked all electrical connections, everything is right, I used the tranny harness for the manual tranny too if that helps.

 

Bump..... anyone have any input at all?

 

Seriously?? wow fine this forum is absoulutaly no help at all.

 

I know very little about this, but if memory serves me right, the 98 uses a gear for the speedometer where the 99 uses a program in the PCM. Regardless, I think you have a problem with the PCM.

 

I would have posted in the trans forum. Ask to have your thread moved. Might have better luck.

 

Moving it was a good idea. I moved it to Transmissions but if there is no help offered here, I'll move it to the 1997-2003 forum.

 

The problem is what you thought it wasn't. There are different types of speed sensors in play here. The only way to correct this is to get a tune to correct the math that the PCM is doing to determine the vehicle speed.

This will also cause other problems since a lot of the functions look at vehicle speed.

Can you get me the PCM codes for the computers in both the vehicle that the parts came out of and on your vehicle? Or at least the year and specifics about the model that the parts came out of and the details on yoiur truck as well?

Darrin

 

the truck the parts came off of- 98 F-250 light duty with the 4.6 came with a 5spd, 3.73 limited slip My truck WAS- 99 F-150 with the 4.6 4spd automatic and 3.55 gears. my truck now has the gears and the tranny from the 98

 

Without having the actual catch codes for the actual trucks in question, I pulled up 2 codes that I am familiar with. I looked at BQQ1 code for the 98 F250 and CFK2 for the 99.

Looking at those and assuming that they might be representative, I can't see the problem as long as the computer has been tuned to shut off the automatic functions. Other than perhaps the transmission harnesses may not be plug and play swappable.

 

I am assuming that your 99 is a 2 wheel drive? If it is it should be getting its speedo info from the rear diff ABS sensor and or the output shaft sensor on the automatic transmission. The output shaft seed sensor from a 99 is different from that of a 98. You will need to find a 99+ M5OD sensor and drive gear and switch to that.

 

Thanks JMC!

My thing is that I can't help much without knowing exactly what both vehicles were equipped with and the easiest way for me to look at that is with the computer codes from both trucks. I am just not that familiar with the older trucks to know exactly off the top of my head what each of them used for what and what the differences are.

But, the 2 computer codes that I looked at both had the speedo signal generated by the PCM, the same speed sensor type and the same "number of holes" for the output shaft sensor count. This doesn't however mean that the speed sensors are the same between the 2 years or that the tooth counts are the same if they both use a gear driven speed sensor. I can't get that info from what I am looking at. If I remember to do it, I can look at the service dvd's for those years while I am at the shop. Maybe that will help me get what I need so that I can offer better advice. Time is a problem right now though.

Or, maybe you guys that deffinitely know the differences can take over. I only stepped in here because he wasn't really getting any answers.

Thanks again!

Darrin

 

I do thank you for your input

 

No its 4x4