OK, here goes 1996 f150 xl 4.9 standard shift. started making metallic sounding scraping noise when accelerating or under load pulling. A couple of days later speedo quit. I thought it was gonna be a speedometer cable or trans mounted speed sensor, but research turns up it has a differential mounted speed sensor that only picks up pulses from reading gear teeth turning in near proximity. I know this system can't be making any noise. So I have to assume that the two things are just co-incidental. I'm gonna change the speed sensor and see if it corrects the speedo issue. The noise has a shenk shenk shenk type sound. Any Thought on what it could be? Remember it only happens under load, when not lugging/accelerating it makes no noise at all. Any help appreciated.

 

VSS is a magnetic sensor that reads the difference between the tone ring teeth and the spaces in between so any microscopic metal bits in the fluid are going to stick to it and make it misread. In that case you can just pull it out and wipe it off and you're good to go. Until it clogs up again. That would tell you it's time for a cleaning and fluid change back there.
When the speedo quit, did it just stop registering your speed or did the odometer go blank too ? A blank odometer could indicate a bad speedo (PSOM), or quite often that's just the fuse - which for some reason is the same fuse that powers your interior light.
As for the noise, you might want to inspect your driveshaft real close for any rub marks - I've seen that happen before.

 

Well the interior light is working, so not the fuse. The odometer is blank, (OH OH). Have to wait for the rainy weather to end before I crawl under it. I can see the -$ -$ showing I'm my eyes like a cartoon character, lol
Thanks for the reply, help is always welcome

 

If the odometer is blank, I wouldn't suspect the VSS. My guess would be the PSOM or the power feed to it. If I recall the interior light for sure, and I believe the power point and lighter is on that circuit - there's a whole bunch of little things on that same circuit that probably really shouldn't be on it, in my humble opinion. Sometimes you can lose power to part of the circuit, especially if someone over the years has been playing electrician under there. I believe the circuit uses a green wire.
Or the PSOM could just be burnt. The good news is that they're not year or model specific - any 92 to 96 f-series will work (although the later ones -94,5,6 - were redesigned and less susceptible to a weak VSS signal, so better) and you can swap it into your existing cluster fairly easily. The bad news is that the mileage is stored in the PSOM, so if you have a low mileage vehicle, your odometer is now going to read whatever the donor vehicle had on it.
You should be able to find one fairly easily for about $50. If you get stuck, get ahold of me and I'll see if I have any U.S. clusters here to rob one out of. PSOM is where I would logically start with that one.
I think your noise may be a separate issue.

 

checked the fuse cover and # 18 10 amp has speedometer on it, I pulled the fuse and it was blown. I replaced it and turned the key on and the odometer came on for about 4 seconds and blew the fuse again. I watched u tube post that had similar problem and was a heat fuse in the airbag control box. any suggestions as to how I should trouble shoot the fuse issue. The wiring is in good shape throughout the truck and very little add on stuff, there has been a different radio installed, and other than that the under dash wiring is stock and in good shape. The truck has spent it's life in central Louisiana and north Mississippi, so no salt/rust/corrosion issues.

 

Pretty sure the only things on that fuse will be the psom, the airbag module and shift control for 4x4, which doesn't apply does it ?
The a/b module is the blue box sorta behind the glove box. I would unplug it and see if the fuse still blows, then the same with the PSOM. If the fuse blows with both unplugged, I'd think a wiring short.
If you do have 4x4, you can also unplug the shift module behind the RH kick panel.

 

Pretty much what I was thinking, no 4x4, so I will proceed with troubleshooting after I get more fuses. I will post results in a day or two, or a week or two, retired so no need to hurry.

 

Poking around on this #18 fuse subject, I saw something about shift interlock referring to the electric solenoid (on the left of the column near the bottom) that unlocks the shifter when you step on the brake. Not sure which is correct, but another thing to check.
Also saw where using a light bulb at the fuse holder will tell you if there's still power getting through the circuit with everything unplugged.

 

There is no shift interlock on a manual transmission truck.

 

Good point. So that just leaves the ABS module, the PSOM or the wiring causing the fuse issue, theoretically.

 

Right, no shiftlock on manual. Bought extra 10 amp fuses and disconnected ADM and replaced fuse and did not blow fuse, re-connected ADM and fuse blew about 4 seconds after key on, BTW the odometer worked when the ADM was reconnected. Removed ADM and opened it up and the heat fuse seems to be the culprit (blackened wire on it). I have de-soldered it and ordered new fuse hoping for a few dollar fix instead of $150 to 200. BTW the thing behind the glove box is the ABS box. The ADM was just below and behind the right side of the trim panel below the steering wheel. I will post here after attempted repair at a later date

 

correction, the odometer did not work after ADM was re-connected. Brain fart.

 

Sorry, meant to say sorta behind the ashtray; may have been beer involved in that typo.

 

No problem here, I sometimes (daily) lubricate this Mississippi public school educated brain up with some Evan Williams and water. The results range from funny to pathetic to sad. But I enjoy it nonetheless.

 

another piece of info that is vital to me, I see reference to airbag control module, and airbag diagnostic module, are they the same, or are their two different things? Still trying to gather enough info to start troubleshooting circuits.