No Cruise Control?

[Utah Dually]

Funny you say that because I was talking to a friend that use to be a Dodge mechanic and he said the same thing. He also said that the brake switch could be a two sided switch, one for the brake and one for the cruise, so either way I am going to check that out this weekend before I try the clock spring. I hope that is it. I am not sure I want to tackle the clock spring thing...

[dripley]

The clock spring is not big deal really to get to. I definitely would start with the simple things first. Brake light switch is pretty simple. I do remember some threads here that the switch did turn out to be the culprit. I get cold chills every time I think about a bad ECM. That was the least fun experience I have had with this truck.

[JOHNFAK]

Though cruise was just a cable that ran near the bell/apps sensor right along side the throttle cable. And maybe a vacuum that runs down by the horn drivers side battery. Unless Im mixing cruise and OD ...... but I know the cruise on the 12v is the cable by the TPS/APPS.

[Mopar1973Man]

Though cruise was just a cable that ran near the bell/apps sensor right along side the throttle cable. And maybe a vacuum that runs down by the horn drivers side battery. Unless Im mixing cruise and OD ...... but I know the cruise on the 12v is the cable by the TPS/APPS.

 

Auto's yes... Manual Trans maybe. Early was vacuum later was fly by wire. Like my truck is fly by wire and no vacuum.

[dripley]

I noticed when i first got mine that when you set the cruise the pedal did not stay down. Every cruise control me and the wife ever had the pedal stayed down when set and came back up when canceled. Never gave it much thought until I found out it was all electronic and not mechanical.

[Mopar1973Man]

Like on my 1996 Dodge Ram (Auto) is a vacuum motored cruise. Which is required to have vacuum motor other than that the transmission wouldn't know when to kick down with throttled deeply pulling a grade. Where with a manual you really can't change gears with cruise set so there is no reason for vacuum motor cruise. There is no throttle plate to open or close on a diesel engine. Just need to feed a throttle signal to the ECM. So it fly by wire.

[Vais01]

Now being that he said the dash indicator came on for the cruise, would that eliminate the clock spring? Just a funny thought here, I have had a mis adjusted brake light switch cause issues like this. The pedal was bouncing just a little down the road and it kept turning the brake lights on for just a split second. Made the cruise not work.

This is an interesting and very good point. Putting that one in the diagnostic tool box.

Another thing is the TPS/APPS throttle validation side could potentially be acting up. If the ECM thinks your accelerating it dumps the cruise function momentarily. If I remember correctly the last time I spoke with Tim (Timbo APPS) he mentioned 2 idle validation circuits are within the APPS. It is a long shot but a possibility.

[dripley]

This is an interesting and very good point. Putting that one in the diagnostic tool box.

Another thing is the TPS/APPS throttle validation side could potentially be acting up. If the ECM thinks your accelerating it dumps the cruise function momentarily. If I remember correctly the last time I spoke with Tim (Timbo APPS) he mentioned 2 idle validation circuits are within the APPS. It is a long shot but a possibility.

I can accelerate in mine and not loose the cruise. Accelerate, lift and it returns to the speed I have it set on. It has been like that since new. 

[Vais01]

I can accelerate in mine and not loose the cruise. Accelerate, lift and it returns to the speed I have it set on. It has been like that since new.

Correct. Once you lift it resumes the cruise. What I am getting at is if the APPS signal is acting up and is sending a mixed message to the ECM. So ECM says good but the ABS system which measures speed says no good and do not resume cruising.

I'm probably over thinking it it's been one of those days.

Edited September 15, 2015 by Vais01

[Utah Dually]

Since I put my truck up for the winter so I don’t get salt on it I just got around to digging it out and looking into the cruise problem. It seems like it is the Servo under the battery tray. It is all dirty and corroded. Didn’t even know it was under there….

[Mopar1973Man]

Most likely got a hole in the body of the cruise control motor or the vacuum line rotted off.

[Utah Dually]

You are right, there was a hole in the body of the motor and the vacuum line was heat checked. It is good to be driving the truck after a long hard winter.... You forget just how much fun these trucks are to drive.... I just have fun driving it.