Hey guys. Newb Ford guy here working on some instrument cluster issues. Truck is a 93 F350 460/manual 4x4.

Issues...
#1, Speedo not working... Have been reading some other threads and think I have it narrowed down to the VSS. According to this thread.. (https://www.ford-trucks.com/forums/1...ferential.html) When I turn the key on the speedo should dip below zero and then zero out and settle if the PSOM is still working. My scenario, when I got the truck the speedo worked, driving down the highway the needle started bouncing and then it just went to zero. ODO still displays mileage, but doesn't change when I drive. When I turn the key to run the speedo needle will dip a little and settle back at zero. I can also hold the reset button down and turn key to run, this displays some codes or some such on the ODO screen.

I'm also assuming that since this sensor is tied into the RABS system is why my ABS light stays on all the time?

#2, Tach... the tach seems to sort of work, but I know it can't be right. It moves, but at idle it's showing about 200 rpm and wound up is only showing about 3k rpm. Been doing some reading, but I'm not seeing any common issues that are pointing me in any specific direction other than to just replace it. Anyone have any thoughts?

#3, Fuel gauge, Normally it sits on "E", but has started working recently... read somewhere that there were possible ground issues. Are there any known locations that I should be looking at to clean up? The previous owner messed with the selector switch (glued it in the dash panel!) so I'll be replacing that... not sure if the gauge signal run through it or not.

#4, Water temp seems to be working, but does seem to be on the low side. Where should the needle be sitting at temp? I've never put a t-stat in it so I don't know what's in it now so it may have a "cool" stat in it. It gets the heater plenty warm so I'm not complaining.

Going to run the engine codes on it tomorrow and see what's what... on that note, where do I find out what do the ODO codes mean? I've Googled it, and have found several different code sets, but they all seem to be for different models. Anyone got a point in the right direction for the codes for a 92-96 F-Series?

I guess that'll do for a first round. Thanks in advance guys!

Chad

 

With the speedometer bouncing and now not working I would guess the problem to be inside the rear end.

Yes the fuel gauge wiring does pass through the selector switch.

Just post the codes back on this thread and we will tell you what they mean. Just tell us if the codes are KOEO, CM or KOER codes. No I do not know of any place on the internet for the codes. What I have seen they lump all three types of codes as one when they mean different problems depending what type of codes they are.

 

Thank you for the quick response subford.

May I assume that if it is an issue in the rear end, it'll turn into pulling the carrier out to replace the tone ring?

Thanks for the info on the fuel switch... I'll get one ordered and see if it rectifies my gauge issues.

Will do on the codes!

Much appreciated!

C

 

normally the problem is in the VSS and not the tone ring.

 

Ok, I'm back to our regularly scheduled programming... Ran the ODO test and came up with a "E 08 6", I'm assuming that's the mfg date or something. Does it mean anything? Speedo did swing all the way to the right side and back to zero. guessing it's supposed to do that...

Picked up a VSS at the Ford dealer yesterday... going to try and get it in this weekend, been too stink'n cold out to mess with it after work. Hopefully that'll fi my speedo issues and keep the check engine light off.

Also ordered a new fuel tank selector switch from Amazon. Hopefully I can get the other one out without totally trashing the dash panel. (as mentioned previously, the prev owner glued it in the hole) Might fix the fuel gauge issues. I did get one tank to read if I wiggled it just right.

Anywho, thanks again guys!

Chad

 

The "E" says the module is programmed for English display mode and should have English graphics (mph). The number appearing after the "E" is the microprocessor revision level.

 

Good deal. Sounds like all is well with the PSOM, and all I need to do is install the VSS and see if we have speedo! (hoping it's that simple!)

C

 

When you take the VSS out if it has junk stuck to it you can wipe it off and stick it back in and see what happens. The VSS itself very seldom goes bad but get stuff stuck to it that came off the gears or bearings.

Most of the time the old will work better than the new one. I have also heard that Ford sells more than one VSS (not verified). I think one has more output then the other depending on the load it has to power (not verified).

Something I put together:


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Subford, Thank you! I'll pull the old one, wipe it down and see if that fixes it. Awesome info! Much appreciated!
C

 

Take care in removing the old one as they do brake sometimes when they are removed.
If they brake they may leave part of the VSS down in the hole that will have to be removed.

If you see no problem with the VSS you might try unplugging the RABS module and see if the speedometer starts working right again.

 

Duly noted. I'll take extra care removing it.

Ok, the RABS module, I've heard of it and understand it's purpose, but not sure where it's located?

THX
C

 

I have had troubles with non-Ford VSS sensors, try to use Ford if you can.

The RABS module should be on your frame rail, inside, behind the driver's front tire. You can also find it by following your brake lines from your master cylinder, it's the only thing that has brake lines and wires going into it.

 

Thanks for the tips RIKIL! ...and I did buy my VSS at the stealership. Read several other places about using OEM vs. aftermarket, figured it was worth the few extra bucks.

I'll look for it when I get under the truck this weekend. Thanks for the point in the right direction!


C

 

The RABS module I spoke of should be behind the dash on the passenger side.

Rear Anti-lock Brake (RABS) Module 2C018 located at Behind RH side of I/P, behind glove compartment (E1 in diagram below):


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Okay, I guess I'll look both places... I assume the one I need to unplug is in the dash (if the speedo continues to be problematic after I clean/change the VSS)?

Subford, might I ask where you're getting the great pics? Ford shop manual?

THX
C