Have a 94 f350 e40d having hard shifting, OD light flashing, speedo and odometer not reading/increasing, abs light. I was getting code 23 and 29 and decided to replace both the tps (fipl) and vss. Disconnected the batteries to reset code and went for a drive. Adjusted the tps, Nothing changed still throwing both codes and shifting is the same.
I have since checked the wiring coming from both sensors all the way to the cluster and could not find a wire problem. Checked grounds, cleaned connections still, nothing.
Wondering if I am missing something any help would be appreciated. Trying to avoid taking it to the shop. Thanks

 

Any other electrical problems such as dome lights not working? The dome light circuit powers the speedo.

 

Is your tach working correctly ?

 

the PSOM is powered by fuse 8 and 18 on the 94 not from the Dome light.


To Be Sure Fuse #8 sure does feed a bunch of other things

 

Please describe how you checked the wires.

 

All fuses are good. Tachometer is working. As for the wiring I took the wires out of the loom running down the frame rail and inspected all the way down. Took cluster out to see if it could have been chewed wire behind dash. Voltage of the tps is 1.1v - 4.10v wide open. The vss is brand new (motorcraft) and is the 2nd one I have put in. I have also inspected the exciter ring inside diff and it looks to be in good condition.

 

So you inspected the insulation. How about the copper part of the wire? What does that look like? Is it intact? Does it have any breaks inside the insulation? Either strip ALL of the insulation off or get a meter and check the wires for continuity. Just taking the wires out and looking at them is fun, but it won't find a bad wire. It's just a waste of time.

 

The symptoms point to the VSS (vehicle speed sensor), Speedo, ABS, PCM, Speed Control all share vehicle speed data. My memory is a little rusty and I do not have access to a manual or wiring diagram. Off work today because of Covid-19 and have time to search online. The next step is to test the VSS signal. Need to check ohms and AC voltage (VAC) output. Do you have a multimeter? How did the connector and terminals look on the VSS? Any corrosion?

 

There are similar Speedo, RABS, harsh shifting threads here on ford-trucks.com for other F-series models, F-150, gasoline engines etc. The Speedo circuit is more or less the same for 1994 and similar year models with gas and diesel engines. If your odometer doesn't work then it is likely the PSOM/speedo/instrument cluster. The link below provides some of the diagnostic steps, but a portion of the text cannot be read.

https://www.justanswer.com/ford/153w...ter-quick.html

 

BTW you code 23 may be from not holding WOT while pulling Code.

since the Spedo is not reading and the ABS light is on then you have to verify the Wiring from the VSS to the PSOM and ABS Junction

Firewall connector maybe ?
Pin 76 G100 PSOM to Splice 107 ?
Pin 21 PSOM to Cruise Servo VSS ?

just a couple that come to mind.

 

anyway there is nothing here that tells me the VSS has failed.... what is the resistance measurement of the Coil ?

 

the vss is brand new. I have not measured the resistance. Where do i start with that?

 

since it's new it's probably a Moot point... but you start my setting your Multimeter to the Ohms scale that will read resistance in the 6K ohms range then measure across the 2 pins on the sensor with the wiring connector disconnected.

Always disconnect Batteries when making Ohms readings else you can destroy your Meter

The same principal goes for measuring the wires for Continuity and checking for shorts to Ground.

https://www.fluke.com/en-us/learn/be...ure-resistance

Depending on what meter you own I could be more specific on the settings.