cruise control

[slomoe]

93 manual. Cruise control on/off, set/coast, resume/accelerate all work. But when set, it keeps picking up speed. Any ideas? Thanks

 

[BigPapa]

My 2nd Gen 12V does this when it's cold. When it's 75 or above it doesn't do it, as bad. I was told it is the vacuum servo.

 

[slomoe]

My 2nd Gen 12V does this when it's cold. When it's 75 or above it doesn't do it, as bad. I was told it is the vacuum servo.

thanksBigPapa, makes sense. I will try that.

 

[BigPapa]

And, I forgot to mention, after it's been on a while, it quits doing it. Kind of like once the servo warms up it works perfectly.

 

[RWherley]

Dose your speedo bounce at all?

 

[BigPapa]

My speedo in my '92 doesn't work most of the time and when it does it reads 10-15 mph fast but the cruise works better on it than my 2nd Gen.

 

[RWherley]

I asked cause i had a messed up VSS on my truck that messed with the cruse, if the speedo works but is erratic it could mean a bad VSS which would mess with cruse since that one sensor runs both things

 

[BigPapa]

I figured my speedo didn't work because the VSS was bad on mine, but if it works the cruise, too, maybe my speedo is bad.

 

[slomoe]

got another servo and installed. Still picks up speed when set.

 

[BigPapa]

Dang it, Bobby......

 

[BigPapa]

Does it do it all the time or is it only doing it when you first set the cruise when it's cold and is steady after it "warms up?

When temps are below 70* mine will speed up for a few minutes when set. It will sometimes continue to climb 10-15 mph past the set speed. I can hit the coast button a few times and stop it and I may have to do this several times until it settles down. After it "warms up" and settles down it works perfectly. If temps are above 70* it MAY do it, but not near as bad as when it's below 70*.

Another issue I have, if I have it set at say, 60mph and speed up to say, 70mph by pushing the accelerator and then push the "Set" button again it will put the pedal on the floor! I have never let it go to see where it will stop when it does this. Since mine is a "conversion" I've always chalked this up as a glitch in my conversion.

 

[Philip]

My truck has done this a couple of times not very long after I ended up replacing the VSS. At the times of runaway CC. The speedo was solid on reading. Then a couple of weeks later the speedo started bouncing.

Also check the plug on the VSS. I have seen the plugs get loose from vibration and cause issues. Look at the terminals in the plug. I have found them out or round.

 

[slomoe]

this truck is new to me. In 93 new, it was an automatic. The 2nd owner installed a clutch pedal, a clutch, an NV4500 and a 3.07 final drive. Nice set up but the speedo and cruise didn't work. I am the 3rd owner. I found the netural safety switch was grounded so the truck never knew it was moving. Also the wires on the VSS were reversed. The speedo now works but reads slow because of the final drive change. The cruise buttons now all work but it keeps gaining speed no mater what I do.

 

[Philip]

Is the throttle position sensor still hooked up and in the circuit?

 

[Bluebird]

Are the switches working accurately on the steering wheel? There are micro size pads inside the switches. Remove three 1/4" screws to open 'er up. Switch(s) pop out...careful micro size pieces. Just my $.02. I've repaired accel/set pad on the back of that particular switch.

Patrick

 

[slomoe]

anybody know how many inches the vacuum pump should pull?

 

[Bluebird]

In the Chrysler/Dodge Ram shop manual it give specifics. I checked my before with a vacuum gauge. It's page/section 5-6. Run engine at idle, 1/2 throttle, 3/4 throttle. Range is 8.5 to 25 inches vacuum. I hope this helps.
Blessings, Patrick

 

[slomoe]

thx Bluebird. Vacuum numbers are what I needed. I get 5 inches no matter what RPM I run the engine. Now I will unhook everything and test just the pump.