my cruise usually works, but every now and then it just stops (truck starts coasting) or doesn't allow me to set it in the first place. i haven't figure out a catalyst (all weather conditions, all speeds, etc). sometimes i can just hit resume and it'll start working at the previously set speed, other times it just doesn't work again for awhile. i'm not too familiar with cruise systems, i've never had one stop working in the past, so i'm not sure where to even begin.

any ideas?

 

Intermittent problems can be difficult to track down but it's probably in the switches.

Does the light go on when you turn the system on?

Is the horn working? Is the airbag light on? Just to rule out the clockspring.

The cruise system can be checked by the dealer, with a DRB. But if you don't want to go that route start with the switches. They are easy enough to replace one you get the airbag off - disconnect battery, wait 2 minutes, then pull a couple of bolts.

 

i've never noticed the horn not working...i'll have to try it next time it happens. the cruise light is on, whether the cruise works or not. i've checked it with a DRB, no faults.

 

If the cruise light comes on/off as you press it, the clockspring is OK.

All the switches use the same wiring, they're multiplexed. If it won't set, I'd start by replacing that switch.

 

what about a vacuum leak? isn't there a one way valve somewhere in the cruise system?

 

The vacuum system is the same as that of the HVAC system.

If it leaked you'd have air blowing out in defrost mode only - that's the no vacuum default. If air comes out the vents or the floor and stays there as you accelerate the check valve, near the brake booster, is OK.

 

that's not it then, my HVAC mode stays put and changes where i tell it to, even when the cruise isn't working. (the AC doesn't always work...but that's a DIFFERENT thread)

 

More than likely you have a bad switch. They do wear out.

 

You can test the switches with a multimeter to see if each component is working. There are different resistances for on/off, set, accel, resume, etc. Look up the FSM in the forum and it has all that great info. Help save you money buying unnecessary parts.

I am having similar issues with my cruise. I replaced the switches, before I would have to press on/off repeatedly before cruise would illuminate on the dash. Now it turns on/off every time, but won't set at all. It was intermittent before and would operate but slowly got worse (would randomly lose cruise while it was on). I have had the P1595 speed control circuits code, and I think it may be a bad ground. I tested the wires between the switches and PCM for the vacuum and vent controls and had good continuity but had an open on the ground sensor circuit to the PCM. Still working on that one. Also replacing my CTM later this week as I am having all of my interior lights and headlights go off completely at random times, pretty hazardous at night when the entire truck goes dark!

Luckily I have a base model so I don't have to worry about programming keyfobs or alarm controls or any other power systems. It is direct plug and play on my truck. Hoping this may also alleviate some of the cruise issues. In my truck the CTM is located to the side of the glove box in the dash toward the passenger door. I can't figure out how to remove it without rolling the dash down, so likely that will be a bit of a headache. Done it before so it should go quickly.

Also had an issue with not being able to complete an emission test as their system said it couldn't communicate with my truck via the OBD II port. I can pull codes and get info with my scanner but it is battery powered. Checked the battery voltage and ground and was good on those pins. Pushed all the pins forward in the connector and going to get retested after the CTM replacement. If I can troubleshoot my cruise issue more I can post my findings here as well to assist you!

 

GNelson, on your '98, the headlights and dash lights are not run via the CTM. That's an '01 and up thing. Remove the glove box and there should be three screws to remove the CTM.

The cruise is not a part of the CTM, it's part of the PCM.

The interior lights, dome, are controlled by the CTM.

So as not to hijack the thread, GNelsons thread continues here: https://dodgeforum.com/forum/2nd-gen...-lighting.html