Hi all,

I'm new to the forum. Other than a 91 Ford Explorer, I haven't worked on this type or vintage of truck before. I've found a few different posts about my issue, but not one that followed up on everything and got to a final solve. I'm going to stay persistent with replies so we can eventually get to a final fix for this issue. Here's the situation for those who'd like to help:

This is a 1990 Ford F-150 Lariat, single cab short bed.
- 4.9L 300 I6, which I've been told is extremely reliable.
- M50D-R2 transmission

I bought this truck primarily as a project, so there's plenty to work on here. The main issue I'm looking to solve currently is my speedometer. It's constantly at 0, and therefore my odometer also will not budge.

I've seen some posts about this referencing the fact that this year (and up to the '91 I believe) have mechanical cable and gear-operated speedometers.

Where should I start on attempting to tackle this issue? I haven't been able to find this cable on the back of my transfer case, but maybe I'm looking in the wrong spot?

I'd greatly appreciate any and all advice, and I look forward to hearing from and replying back to you all.

Thanks again,

Skyler

 

Cable should attach to the back of transfer case just above the yoke for the rear driveshaft. Check the large nut on the yoke because, if it loosens it can cause speedometer issues.

 

Hi all,

I found what I was looking for!

Spinning this did nothing for the speedometer, and I felt resistance while spinning it, almost like there was a thick fluid around the gear, if that makes sense. Definitely not free-spinning, if that's what it's supposed to be like.


Transfer case shot facing towards the front of the truck.

A bit off topic, but I'm not sure what this female connector is or goes to... any thoughts?

Wide shot, looking a little leaky or weepy, any thoughts on good seals for this?

Close up shot, gear seems to be okay physically, but spinning it, there's a bit of resistance, like I'm spinning it through dirt or something. No movement of the speedometer whatsoever. Additionally, it wouldn't matter that my battery is disconnected for this, right?

 

Not sure if you got a notification for this, but I think I found what you're talking about. Thanks again for the reply!

 

It sounds like you've already determined that there's resistance when you try to spin it.
Did you spin it by hand?
What I did with my '88 was, I removed the plastic yellow gear and tried spinning the cable itself, while it was chucked in a cordless drill, very slowly, definitely not full speed.
If you've already determined there is resistance, I've read on these forums where people have removed the entire cable and soaked it in kerosene or some type of penetrating fluid, by coiling it in the bottom of a container. Just don't bend it too tightly.
If I remember right, spinning counter clockwise makes the needle move up, but I'll double check that and edit my comment.

 

Battery connection shouldn't affect reaction from the speedo. Spinning the gear by hand may not be fast enough to register on the needle. If the cable was connected and no reaction from speedo. when driving, then the cable may be broken inside the sheath. Look inside the hole for the cable with a flashlight and check the condition of the internal gear. If it looks undamaged then a broken cable is probably the problem.
Female plug is probably for the 4x4 indicator light.

 

To lube the cable
The cable has to come up and out from the top (behind the cluster)
Remove the inner cable completely, clean it off and spray white lithium grease into the housing while you reinstall the cable
When they get hard to turn like that, they like to chew up the plastic drive and driven gears
The empty connector is for a VSS for cruise control your truck must not have
Lube the cable and retest
If the outside housing gets worn, no amount of lube will fix it

 

Yes, I spun it y hand, both counter-clockwise and clockwise. I figured that even just spinning it by hand would at least budge the damn thing, but maybe I'll put it into a drill and give that a shot. Thanks!

 

That makes sense... I'll toss it into a drill chuck and see if higher rpms will move the needle. I tried looking in the hole for the internal gear but the angle was too steep, maybe I'll try taking a picture with my phone since my fat head can't get close enough without hitting the underside of the bed, lol. Thanks!

 

I'll work on it a bit more today, but I'm not looking forward to pulling the dash out, all that 34 year-old plastic is pretty brittle. Any resources you know of on how to remove it, or should I just be super careful and take my time?

As far as cruise control goes, interestingly enough, my steering wheel has buttons for it... though I can't confirm that the steering wheel is original, since it's pretty shoddily installed and moves around quite a bit. Thanks!

 

The empty hanging plug is for cruise control, when you buy a VSS there is an option for cruise control or no cruise control.
Your plastic yellow gear looks okay, a little bit of wear but all good there.
Yea, sadly you got to pull the dash... but it really isn't that hard, just take your time and be gentle.
Once the instrument cluster is free, you might be scratching your head as to how you can pull the dang thing out enough to get your hands back there.
Get underneath the truck and free up that speedo cable, might help to have an assistant feed the speedo cable back into the cab while you pull the Instrument cluster further out. Don't forget to pull the two big electrical connectors out of the back of the cluster.
As far as removing the speedo cable from the cluster, I don't remember... I think you squeeze the plastic connector and then pull?
Best get a second opinion on that last part.
Best of Luck

PS: Now would be a great time to remove/repair any broken or burnt-out bulbs from the instrument cluster. Some times all they need is a little cleaning and bend a tab here or there on the bulb to get them working again.

 

You do not need to pull the dash out or even remove the cluster to get the spedo cable off the back of the cluster and lube the cable
You just have to fight and swear some as you get the Bandaids out
You push the little square tab on the round cable to get it off the back of the speedo
If your big hand will not fit up in there
Pull on the cable while pushing the tab with a long screwdriver or pick tool
I believe your housing is worn and your speedo will jump if you do get it working
You should be able to see speedo needle movement just twisting the cable with your fingers
If you cannot and think you need a drill, your cable is gummed up bad
Disconnect both ends in that case and run some Brakleen down the housing with the cable removed and then lube it back up

 

If I don't remove the dash, how will I get to the cluster-end of the speedometer? I'd rather take some cuts and scrapes and swearing than pull the whole dash out lol. Also, yeah it must be gummed up pretty bad because it absolutely doesn't budge from spinning it at the transfer case side.

 

Quick update: I found where the cable goes up into the dash. I gave it a few small tugs while trying to find where it went into the front side of the truck (from under), and it seems like it came loose? Not totally out, but it definitely has more slack than it did previously... maybe I pulled it loose? Could it be that it was just poorly connected?



Pic of where it goes into the front end side of the truck. Pulled on it a bit and it might have come loose?

Also a bit unrelated, but while I was down there, I found perhaps a much bigger issue... my transmission case seems to have been improperly re-installed... the guy said he replaced the clutch. How much of an issue would this cause? Major concern? Thanks!

Large gap seen here

Not all bolts are installed, looks like this plate isn't even original because the holes don't seem to line up properly.

 

Did the cable still bind up when you removed it from the speed sensor?