BigBlue

For some reason, my cruise won't hold unless it's set at 75. It tries to, but it won't. It quit working after I hit this really big hole 4 wheeling. I also think my 4 wheel drive may be messed up (not sure about that). Any idea what's wrong? Thanks for the help.

AlpineRAM

BB I'd suggest looking into the vacuum stuff on your truck. Maybe you've got a lose hose that will let air in, just enough to render the vac pump helpless at lower rpm. This would also cause the central axle disconnect going out. (No Vac-no movement)

Just my 2c

AlpineRAM

BigBlue

Alright. Now here's another question. Where do I start looking for the vaccum stuff? I assumed it was a vaccum line, but I didn't know where to start looking.

quantrill88

if you hit a hole while wheeling, you might want to look at the lines goin to the front axle disconnect. the motors on the left side of the axle. maybe something got snagged off.


jeff

rjordan

so drive faster than 75 and all is well

jthorpe

Mine did this a while back and I found that the VSS was bad. I replaced it and all was good. Could be that, but who knows.

dakar

To find a vaccum leak on a gasser I would just take a can of starting fluid or carb cleaner and squirt down the hoses/fittings one at a time, as soon as the engine stumbled a bit or the idle dropped i know i found the spot. Don't know how well if at all this would work on the diesels....same i'd guess....

AlpineRAM

Dakar- it wouldn't work since the disel uses a vacuum pump and doesn't have intake vacuum. The vacuum pump has an exhaust into the crankcase.
For checking I usually use a small hand-operated vacuum pump with a manometer and disconnect circuit after circuit and see whether it holds the vacuum or not- therefore I can isolate the circuit. Then I follow the circuit and unplug the next connector and (having the first connection plugged) I test the line.

HTH

AlpineRAM

dakar

Ah cool.... now you went and did it... the day was almost over and I hadn't learned a dang thing...now you went and ruined it!! Now I have to wait till tommorrow and start over again!

Seriously, thanks for the clarification I had no idea.

BigBlue

Well, after taking it to 2 dealerships, they've found out that my crusie control sender or something like that is bad. May be other stuff wrong, but that's all they've found so far. First dealership said the truck was "surging" and they wouldn't fix it. Had no problems with the second one. Don't know if it was because they were more competent or because my dad took it in instead of me.

Palmetto_kid

Glad you got it fixed. Was it something that you could have changed out if you had known what it was the culprit?


PM the name of the second dealeship. Just wondering which one it was.


later.
phillip

BigBlue

Turns out it was the cruise control servo. Truck ran fine for the second dealership. No "surging" or leaking fuel.