Hi Folks,

I have a 1998 F-150 XLT 4.6 w/auto Off-Road package with 89750 miles and a speedometer that does not move at all. This truck has a mechanical odometer as well. I have read through all of the forums for the past couple of days and can report the following.

Replaced VSS.
Cruise control works fine.
The ABS light does not stay on.
Trip meter works fine.
Odometer works fine.
All other gauges in the cluster are working fine as are all of the cluster lights.
Fuse #2 is fine.
Fuse # 29 is fine.
All of the standard diagnostic lights come on and shut off normally when the vehicle starts.
I have pulled the cluster, wiped down the contacts, rubbed a pencil eraser on the contacts, and put the cluster back in and still no speedometer.
I have tried a little percussive maintenance, but not too hard, and that hasn't seemed to fixed the problem.

Did I miss any other diagnostics, tests or suggestions?

Thanks for any and all help in this matter.

 

Does your radio have the speed volume control ?

If so, set it to 6, and see if the volume goes up with the speed. This tests teh VSS circuit in the truck.

 

I have an aftermarket stereo in it now because the truck came with an AM/FM Cassette radio. I still have the original radio, so I can install it and see if it has the speed volume control.

If the radio does not have speed volume control, is there any other tests I should try?

 

I THINK (heavy on the think part, because I haven't looked at a spec.) the cruise control works off of the VSS, so it cruise works your VSS should be OK. The speedometer itself may be broken internally. Maybe you could find one in a junk yard? Good luck.

 

Can that, I was not thinking straight last night. The CC working is a good enough indication of the VSS working.

If you can do it ( you will need some wire, and checked that it is installed correctly )

1. With VSS installed
2. Unplug cluster
3. crimp length of wire long enough to reach back into the cab to the pink w/ orange stripe wire on the VSS connector ( again with VSS installed ). Verify this is less than 5 ohms of resistance on the wire added.
4. Test resistance from cluster connector pin #7 ( gray w/ pink wire ) to the wire that you attached to the VSS.

-> if the resistance is between 200 and 300 ohms, the cluster is the problem.

That is really the only test to run. If the resistance is infinity ( and you are sure you have the added wire spliced correctly with < 5 ohms ) then there is a problem with the VSS to the cluster wiring. This would be start with checking the connector pins, and the wiring to the VSS.

Hope that helps a bit more then my last post, with redundant testing.

 

That is a great suggestion, thank you very much. I will test with my ohm meter and see what the resistance is.

I will check this out tonight and report my findings back.

Thank you again for the help.

 

Okay, so here is the report & I wish I had better news.
I don't have a pink w/ orange stripe wire at my VSS but instead a red with black wire and a black and green wire. I tested resistance on the red with black wire, using a splice wire that had 0.5 ohms of resistance, and all I got was infinity readings after testing all of the pins on all 3 plugs. I then tried resistance on the black with green wire and got a myriad of readings on different pins but nothing greater than 47 ohms.
That being said, unless I screwed up royally, I should have gotten a reading at the cluster when patched into the red with black wire if there are not breaks it in between the VSS and the cluster. Correct?
So it sounds like it might be a broken wire but I think I would have preferred it be the cluster.
Is there a proper way to splice in new wiring or am I better off getting a new wiring harness?
If I need to get a wiring harness, are there more than 1?

 

The VSS only shows a 2 pin connector on it.

Are you sure you have the VSS ?

 

Boy, if I wasn't testing the VSS cable I will feel pretty dumb.
I was testing the wiring that has a 2 prong connector that goes into a sensor that is on top of the rear differential. The sensor faces towards the front of the truck and is secured with 1 bolt. The wires associated with the 2 prong connector are red with a black stripe and black with a green stripe. I wish I could post photos just to show what I was working on.
I apologize if I was unclear in previous posts.

SSCULLY, let me know what I can do to clear up the last post. Thank you for your patience and assistance.

 

OK, that is it, you posted 3 plugs, and I read 3 pins.... my mistake.

If you have the same color wire ( on the truck''s harness ) at the cluster, and it does not read between 200 and 300 ohms, go to the VSS and measure across the 2 pins on the connector to test the new VSS.

Bit confused on the colors ( 1997 EVTM 62-2 )


If you test the VSS good. ( which it should considering the CC works )


Time to check the connector to the cluster again.

You are looking for C237 this should be a back ( not 100% sure on that one ) connector, looks to be a single row of pins, locking tab off center.
When you pull it out of the back of the cluster, looking at it, the locking tab should be to the right of center, and pin 7 the 7th pin from the RIGHT ( looking at the mating side, that is why it is not L to R ).

 

I see what you mean about being confused about the wire colors. The schematic you posted is pretty clear about the colors on a 1997 and I am surprised that mine are different. I wish I could post the pictures that I took to show that mine are different.

Is there a way to tell which side of the connector the pink with orange wire is on? I am not familiar enough with reading these schematics to know.

I will test across the VSS and see what the resistance is.

Since the CC works, would it be safe to assume that any wiring issues would be localized to the dash board harness?

 

Actually I might have assumed too much. The colors in the diagram are for the Truck's harness side.
I never confirmed that this what you are talking about ( thought the connector was on the VSS itself ??? )

Does the VSS have a pigtail to a connector on it ( like a Power window motor ), or a connector ?

You would just need to peel back the cover on the trucks harness to verify the harness color.

I would think that it is safe to say that, but we really should confirm it, before moving on. By the CC and Instrument cluster diagrams above, there has to be a splice in it, to go to both the cluster and to the speed control servo.

 

I would assume that it is what you called a pig tail. It has two clips, on each side, that slide over the top of two tabs. I pulled back the ribbed cover that is slid over the harness and can see the 2 wires that go into the pig tail connector.

Can I send you an email with a photo of what I am looking at?

 

SUCCESS!!! The speedo is fixed.

I wasn't ever able to get my analog or digital multimeter to read 200-300 ohms on speedometer plugs, but I found another speeometer cluster in a junkyard today for $50, got it home and installed it, and voila the speedometer, odometer, tripometer and all of the gauges work!

Thank you SSCULLY & 06 So Comfort for you input and assistance.