Ive tried doing some search for this on here but unfortunately i find this site hard to search with all these sub-forums it has.

My question : can someone tell me where the speed sensor is and if you have the wiring diagram , what color wires go to the ecu from the sensor AND more importantly color of speed signal wire going to the GUAGE CLUSTER .

what do you think might happen if i drove the truck with no signal coming from the speed sensor i.e CEL ? systems malfunctioning ?

TRUCK : 98 F-150

any help would be appreciated


Z

 

There should be a gry/blk wire from the VSS that runs to the speed control servo and to the PCM but I'll be danged if I can find the speedometer on the wiring diagrams in my Hayne's manual. Wonder why the tach and other gages are shown but no speedometer?

A wht/pnk wire runs to the tach. Maybe the speedometer works thru the tach?

 

thanks for the reply
actually you're right about the speedometer running off the tach since in japanese cars i know for sure they're connected , if the vss stops working , the tach will stop reading.
my other question is , does this truck use the speed reading for other accessories ? so if i drove on it for a little with no speed reading , shall i expect any CEL or such things?

 

Welcome to the forum texanF150

The VSS is on the back of the transmission. The grey/blk wire that ddruman mentioned goes from the VSS to the instrument cluster, the GEM, the cruise control module and the PCM.
With no reading from the VSS you should eventually get a check engine light and a P0500 trouble code.

 

oh god what am i thinking , i must've read ddrumans post when i was half asleep. My truck DOESNT have a tach , i had thought you meant odometer not tach . yeah what i meant was in cars ive seen the odometer reads from the speedometer.
Ok so i guess i whould be looking for a grey/black wire in the back of the guage cluster.

So does can anyone tell me still how id reset the check engine light and trouble codes on this truck (assuming everything is fixed and they wont come back on again)

thanks for all the help everyone

 

After you've had it scanned to see what code turned on the check engine light you can just remove a battery terminal for 5 or 10 minutes to clear the code.

 

I have been watching the posts for my problem and this description is close. When I wash my truck the speedometer quits working. The odometer and trip odometer continue to work. When the truck dries out the speedometer works. I believe a terminal at one of the connectors on the frontwall gets wet and the increase in resistance is enough to cut the signal feed to the speedo.
Cruise control is disconnected via recall 05V388000 awaiting parts, so I am not able to try cruise when the speedo is not working. Speed sensor is on the transfer case and the terminals on that connector are clean and dry. No trouble codes are present.

I have a 1997 LD 250 4x4 with 5.4l engine and AOD transmission.

 

A lot of speed sensors are on the differential.

 

Welcome to the forum geobenz

If the odometer keeps working then that means that the speed signal is getting to the instrument cluster. The problem is in the speedometer.
If you do a search here you'll find info about a bad solder joint on the back of the instrument cluster. Quite a few people here have resoldered it and successfully repaired the problem.

 

Thanks for the reply. Must be coincidence with the washing. I will take a look at the cluster.

 

Okay, sorry if I am being dense tonight, but, the symptoms I had are the bucking, jerking shifting, no speedometer reading and o/d light flashing with the ABS light solid. The truck threw an error code 452 which my manual says insufficient input fro vehicle speed sensor. So far, so good. I picked the sensor up from the local parts store which has an two pin electrical connector and an input for the speedometer cable. The problem is I can find no such item on my transmission nor can I find a speedometer cable coming throught the firewall. After reading several posts, I'm thinking it must be in the differential. I pull that sensor but the local parts store cannot find any VSS but what they sold me. The sensor that I pulled from the differential is listed as an ABS wheel sensor.

After all that, now to my question, what is the difference between the two and where can the VSS be?!

Thanks,
Dave
1995 Ford F150
5.8 w/ E40D

 

I think the VSS is towards the back of the transmission on the driver side , i believe it reads speed from the output shaft of the transmission .
And yes the sensor on the differential is going to be your ABS sensor which will not give you such symptoms if it goes bad .
For the function of that ABS sensor and exact location of your VSS ill leave it up to Racerguy or someone more knowledgable in these truck to answer.

 

Thanks texan, I have looked all over the transmission and I cannot find anything like what the parts store sold me or that has a speedometer cable going to it. Anyone have any ideas?


Thanks

 

Your truck uses the rear ABS sensor as the VSS. It's the one mounted on the top of the rear end.

 

Thanks Racerguy, you are correct. In the interest of helping others, I want to share my experience. I had already picked up the ABS sensor for the differential in the hopes that replacing it would correct the issue (interestingly enough, advance auto parts did not carry it but NAPA did). I replaced the sensor with no difference (still no speedometer, ABS light on). I then began tracing the wiring and lo and behold I found that the wire was cut in two! It appears from the shape of the wire loom that it had been rubbing against the shock absorber for some time and finally cut the wire.

A quick solder splice, dielectric grease and taping and all is well with the world again.

Thanks again to the forum as it got my in the right area for the sensor and the problem.

Powells_F150
1995 Ford F150