More Cruise Control Woes

[Madurski]

92 W250, Automatic, cruise hasn't worked for quite awhile and over time I have done the following.



Things checked/replaced so far:



Switches (brand new)

Servo motor (used)

Clock Spring (Used but tested)

Vacuum (plenty)

PCM (Cleaned pins, no loose wires)

Brake switch works fine

Speedo works fine



What am I missing or what else can I test? Any decent wiring diagrams that show the cruise circuit(s)?



Please help, my right foot is tired

 

[Steve Graham]

The best detailed wiring diagram is the FSM, (factory service manual).

As far as getting the cruise control working, mines been a problem from day one. After several trips to the dealer I gave up. sorry.

Steve

 

[Simplysmn]

does your speedo work ? correct me if I am wrong but aren't they both in a round about way hooked to eachother ?

 

[KOG]

I'e got a Rostra aftermarket on mine which came without. Works well, as electric servo units usually do. It might be less trouble to just install aftermarket. Factory cruise has worked well on our gas engined Chrysler stuff, but I'm not too sure about the diesels.

 

[dpuckett]

If your right foot is tired, it's time for more fuel. :-laf



All kidding aside, are you SURE the servo is good? What about the clip holding the servo cable onto the bracket where it adjusts? (near the TV cable, near where the throttle rod connects) Clip MIA on Mom's the year I owned it. For that matter, what about the adjustment altogether? You didnt mention that. You can make a clip out of a piece of baling wire or coat hanger. Bend it around to fit. Has stayted well in mine so far. Just have to get vacuum back to it now.



Daniel

 

[JTCHess]

My cruise control has worked sporadically since I've owned my truck (10 years) and since installation a trailer brake controler last year has ceased to work altogether. I've given up on it.



John

 

[boatpuller]

My cruise control worked perfectly for the first 7 years I owned the truck but now it comes on fine and as long as it's flat it's ok, when it gets to a hill it gives more throttle but when the hill levels out it doesn't back off on the throttle but starts giving more. Can't find anything in the manual about that. Did find a Tecnical Service Bulletin 08-07-93 about speed control surge, but I'm not sure if what mine is doing is considered surge, also if you hit resume it puts the hammer down enough to through you back in the seat, black smoke and all but just keeps going till about 10 MPH past where it was last set at.

The TSB says this



3. If no problems have been found to this point, the speedometer drive gear on the output shaft of the NP 205 transfer case may be at fault. Remove the speed sensor, adapter and the speedometer drive gear. Carefully inspect the speedometer drive gear while rotating the output shaft. Any cuts or irregularities on the gear can cause a speed sensor signal variation. If any irregularities are present, proceed to the repair procedure.



then it says to replace the drive gear in the transfer case, it only gives . 6 hours to do the job so I wouldn't think it's real hard but after looking at the manual it looks like yo have to pull the back off the transfer case. has anyone done this, is it a major project?

Here's a link to the TSB



http://dodgeram.info/tsb/1993/08-07-93.htm



Thanks,

Caleb