Speedometer Cable 1987 Ranger Auto/2wd

[freedom5]

What is the difference in the 2 wheel drive and 4 wheel drive speedometer cable? I have a 4LD tranny. Some parts stores only list the 4wheel dr. I also noted some cables 70" and other s 80". My speedometer seems to be accurate on MPH but the needle started fluxuating and I can detect a slight noise when it does.

 

[RonD]

The 70" cable runs from trans output to cruise control in engine compartment

80" runs from trans output and into the back of the dash, so no cruise control.

It is probably a frayed speedometer cable, BUT........it could be the speedometer itself.
You can pull out the dash and use a drill on the speedometer to test if it is working without jumping around, if so then replace the cable.

 

[freedom5]

Thanks Ron. I have cruise control so is there a cable that also runs from the transmission to the cruise control in the engine compartment? My cruise control works perfectly. Where is the cruise control in the engine compartment located?

 

[Spott]

Not so sure about that... at least in the '88, there was no mechanical cable from the trans to the CC. The CC uses the electronic VSS signal (via wires), and the speedo uses the mechanical cable.

A few years ago, my speedo started jumping a lot, and after a while, would only respond under acceleration. Turns out the driving gear inside the Tcase (or trans) was worn until it had no teeth left. I'd take the speedo cable out of the tranny, and poke your eyeball up there: a good gear should have a flat profile, a bad gear will have a "saddle" worn in the center. It's not too hard to replace.

My speedo also jumps around quite a bit a high speeds, and it's worse in the winter. I'm pretty sure there's dust or crud in the bowl-piece, or a shaft is bent.

 

[RonD]

Thanks Ron. I have cruise control so is there a cable that also runs from the transmission to the cruise control in the engine compartment? My cruise control works perfectly. Where is the cruise control in the engine compartment located?

Look at the throttle on the intake, you will see two cables, one goes to the gas pedal inside, the other goes to the Cruise control in the engine compartment.

Yes they did add a VSS that ran off the same gear as the speedometer cable, and it was used by cruise, PCM and anti-lock, I believe.
Not sure what year that was added.
My '94 was the last year of the cable, speedometer/odometer was electronic in '95

 

[Spott]

Look at the throttle on the intake, you will see two cables, one goes to the gas pedal inside, the other goes to the Cruise control in the engine compartment.

Yes they did add a VSS that ran off the same gear as the speedometer cable, and it was used by cruise, PCM and anti-lock, I believe.
Not sure what year that was added.
My '94 was the last year of the cable, speedometer/odometer was electronic in '95

I'm pretty sure he's asking about the speedometer cable (the fat square one that spins) and not a throttle cable (the skinny round wires that pull). There is a throttle cable on the CC vacuum servo, but there's no speedometer cable.

I'm guessing the longer speedo cable is for the 4wd, to accommodate the additional length of the transfer case. You could probably make it work on a 2wd if you had to, but you'ld have to secure the extra length somewhere.

 

[RonD]

He was looking for the cruise control module, which is at the end of the cruise control throttle cable

 

[Spott]

Still not believing, even slightly, that the mechanical speedo cable goes to the CC. I took my CC off a junkyard '87 B2, and all it takes is electronics and vacuum.

Also, the CC module is above the driver's left foot. The part in the engine compartment is the vacuum servo, which doesn't process or calculate anything.

 

[adsm08]

Still not believing, even slightly, that the mechanical speedo cable goes to the CC. I took my CC off a junkyard '87 B2, and all it takes is electronics and vacuum.

It does. Kinda.

The CC module needs a VSS input or it can't maintain speed, it can only hold throttle. The mechanical speedo cable plugs into the VSS sensor, which in turn is driven by the gear in the trans or the T-case.

Since they are all mechanically linked anything that can affect the speedo can effect the cruise control.

Last summer my speedo cable casing melted on my headers, flowed down in the cable, and locked it up. The result was a stripped drive gear on the VSS sensor, since the gear is only made of plastic. If my truck has cruise it would have been taken out at the same time the speedo died.

 

[freedom5]

Update

What is the difference in the 2 wheel drive and 4 wheel drive speedometer cable? I have a 4LD tranny. Some parts stores only list the 4wheel dr. I also noted some cables 70" and other s 80". My speedometer seems to be accurate on MPH but the needle started fluxuating and I can detect a slight noise when it does.

Thanks to everyone who responded. I got it done! The shorter speedo cable is the one that fits my '87 XLT. There is an electrical sensor at the Transmission that sends the rpm to the vacuum canister controlling the cruise . The most difficult part was removing the instrument cluster to disconnect and connect the speedo cable to the speedometer. I needed to replace the bulb illuminating the clock and radio so did that while I had access.

One tip is if you ever have to replace the cable you must pull it through and insert it from the firewall on the inside as the speedometer connection is too large to go through the opening.

My speedometer cable had two crushed places which caused it to bind. It had been routed below the frame and something had hit it or snagged on it. I made sure the new one was routed inside the frame channel and tied off with plastic zip ties.

Again - thanks to all. Hope this will help others.