2nd Gen Non-Engine/Transmission Cruise control wows.

[Texis]

I, like many have experienced the creeping acceleration when the truck was on cruise. It just keeps climbing. BUT it only does this in the winter?? If the temp is above 75 degrees it worked fine. I searched the forum and found this;



http://www.youtube.com/watch?v=ppcUyQZ14AE



So, I took the solenoid out per the video, sure enough one of the pistons was rusted and stuck. So I used a 600 grit paper and polished the pistons. Everything went very smoothly and went back together correctly. The pistons were moving freely, so I reinstalled the assembly.



First run, cruise "acted" like it was trying to work, but couldn't keep the truck at the speed setting. . so, I took it back apart and went through the process again to double check my work.



Back together, second run. NADA, nothing... cruise doesn't work at all??? And the cruise light (green on the wheel) will now not even stay on now?



What next? Why did it work "somewhat" before with stuck piston and nothing at all now? Any suggestions would be great as I have a 1200 miles trip coming in 3 weeks.



Thanks

 

[GAmes]

Are you sure you reassembled it correctly? Once you have figured out the power issue you might have to retrain the PCM. The procedure is in the FSM. Neat video, I bookmarked it.

 

[Texis]

Yes, it is assembled correctly, opened it up twice. Retrain the PCM? OK, so I have looked all over the site. . what is the FSM?

On further investigating. . when the green cruise light goes off, If I restart the engine it comes back on, but no cruise control at all? Stays on about 2 minutes then goes out again.

I did have to disconnect the battery to remove it and the tray, for access to the cruise control assembly.

 

[Texis]

Reset the PCM (disconnect negative battery terminals and turned key to "start") . . had no effect. Green light stays on for 1-2 minutes then goes off. No cruise at all?? Truly baffled at this point!

 

[Sticks]

Did you clean the bore of the rusted one? may still be hanging in the bore.

The video the guy did not go through that, and used penetrating oil (I roll my eyes at that every time I hear it - Penetrating oil is not a lube), should have used a very light grease, 10wt oil, or left it dry.

Electrical - did you damage the circuit board, or wires to the plug?

Check fuses.

Might also be that you broke a vacuum line. Very brittle on trucks this old.

 

[Texis]

Yes, I did clean the bores. I used a 25 cal. rifle brush, just the right size. Don't believe I damaged anything on the circuit board, as I never put any of the assembly into a bind. I did add some oil on the first round, but when it didn't work I pulled it apart and cleaned any oil out of it... won't work either way.

I changed out the vacuum lines near the unit this morning, it broke as I examined it (brittle) so that is now fixed. But still getting the same result, green light will stay on for about 2 minutes. Have to restart the truck to make it come back on, and ZERO cruise control. It doesn't even try! Acts like there is no signal to the unit?

Where is the fuse? neither in-cab fuse panel nor under the hood have any fuses indicating "cruise control" or "speed control". Having no other issues with the trucks electrical system. Still messing with my head how putting the clean up on the coil pistons could stop the entire system from functioning!!

I am beginning to think that disturbing the plug connector broke it internally. I didn't get rough with it but this stuff is getting old and brittle. Dunno???

 

[GAmes]

FSM is factory service manual, a tool that will pay for itself in no time. I prefer the paper book version http://www.genosgarage.com/1997-DODGE-RAM-FACTORY-SERVICE-MANUAL/productinfo/DFSM97_PRINT/ but dome prefer the CD http://www.genosgarage.com/1997-DODGE-RAM-FACTORY-SERVICE-CD/productinfo/DFSM97_CD/ They also contain full wire diagrams, makes it easier to figure out which fuse goes to what. I can't get to mine right now, so I'll look tomorrow for which one it is. I believe the FSM also has troubleshooting procedures for voltage at the CC plug.



The computer has a memory that you need to reset. The procedure is in the factory service manual. IIRC you need to set the cruise, then shut it off about 20 times. Once you get it working the key to prevent re-ocurance is to keep your foot on the pedal and hold the chosen speed for a few seconds. When you set the speed and immediately release the pedal the computer searches for the correct setting. Eventually it starts acting like yours is doing.



I replaced my servo once a long time ago, then it was only about $40.

 

[Sticks]

Looks like the cruise function gets everything from the PCM (power to the switch, etc).

You sure there are no codes? Key on/off procedure and watch for the DTC light to start flashing (if equipped)? Codes 12, 15, 34, 55, and 77 will all be cruise related.

Power to your cruise switch is a yellow/red wire. Black connector under the dash, 84 pin, the cruise power should be pin 79.

There appears to be a second one, probably closer to the steering wheel that is I think a flat 5 pin with only 4 wires, still yellow/red is your power. Pin 1.

 

[Texis]

Thanks for the info, very helpful.

Is there ANY logic to cruise functioning (but only above 70 degrees and periodically accelerating) to NOTHING at all AFTER I pulled it apart and cleaned it up?

This is what drives me crazy, why would "all of a sudden" the truck come down with an electrical problem in the steering column, PCM, etc by cleaning the pistons in the servo unit coils? I must be missing something simple!!

I may just buy another servo and stick it in there to see what happens!

 

[fest3er]

First, verify you are getting vacuum to the servo.

Second, manually test the servo. You'll need a set of simple small gauge alligator clip leads; this is a low current test. Unplug the connector on the servo; don't work with the cable connector; only the servo. There are 4 pins on the servo's connector.

1. Vacuum control (increase speed)
2. Vent control (decrease speed)
3. Power (+12VDC)
4. Ground

Get a set of simple small gauge alligator clip leads; this is a low current test. Start engine. Jumper B- (ground) to pin 4. Then jumper B+ (power) to pin 3.

If you err in the next step and the engine speeds up too much, remove power from pin 3; this will return the engine to idle.

Now *very* momentarily apply 12VDC to pin 1; just brush the connectors together for as short a time as you can, as though you're striking flint. Do it a few times if necessary. The engine should speed up. Then momentarily apply 12VDC to pin 2; the engine speed should decrease. If nothing at all happens, try grounding pins 1 and 2; it's been a few years since I ran this test and I don't remember what activates the vacuum and vent solenoids.

If nothing at all happens and you know good vacuum is reaching the servo, you'll know the problem is within the servo. If the servo controls engine speed, you'll know the fault is elsewhere.

If you have a bench supply of vacuum and a 12VDC supply, you can bench test it.

 

[fest3er]

First, verify you are getting vacuum to the servo.

Second, manually test the servo. You'll need a set of simple small gauge alligator clip leads; this is a low current test. Unplug the connector on the servo; don't work with the cable connector; only the servo. There are 4 pins on the servo's connector.

1. Vacuum control (increase speed)
2. Vent control (decrease speed)
3. Power (+12VDC)
4. Ground

Get a set of simple small gauge alligator clip leads; this is a low current test. Start engine. Jumper B- (ground) to pin 4. Then jumper B+ (power) to pin 3.

If you err in the next step and the engine speeds up too much, remove power from pin 3; this will return the engine to idle.

Now *very* momentarily apply 12VDC to pin 1; just brush the connectors together for as short a time as you can, as though you're striking flint. Do it a few times if necessary. The engine should speed up. Then momentarily apply 12VDC to pin 2; the engine speed should decrease. If nothing at all happens, try grounding pins 1 and 2; it's been a few years since I ran this test and I don't remember what activates the vacuum and vent solenoids.

If nothing at all happens and you know good vacuum is reaching the servo, you'll know the problem is within the servo. If the servo controls engine speed, you'll know the fault is elsewhere.

If you have a bench supply of vacuum and a 12VDC supply, you can bench test it.

 

[Sticks]

Thanks for the info, very helpful.

Is there ANY logic to cruise functioning (but only above 70 degrees and periodically accelerating) to NOTHING at all AFTER I pulled it apart and cleaned it up?

This is what drives me crazy, why would "all of a sudden" the truck come down with an electrical problem in the steering column, PCM, etc by cleaning the pistons in the servo unit coils? I must be missing something simple!!

I may just buy another servo and stick it in there to see what happens!

Sometimes a non-serviceable unit just does not like to be serviced. I've had it more than once on a variety of different things. Sometimes you get lucky, others you just finish it off. If you were too aggressive in rust removal, you may have made it worse and the pistons are now binding, maybe nicked an 0-ring or got some dirt/contamination inside the servo housing.

Like an auto trans that is on it's last leg and the fluid is uber nasty. DO NOT CHANGE THE FLUID.

 

[MLee]

"IF" you still have the surging after your rebuild-----you might do what I did. Read on here for this problem of surging/acceleration, put one of those little red spray can nozzle tube down the vacuum line, some how this works I did it and no more problems.

 

[Texis]

Thanks for all the inputs. Would any of this explain why the cruise (at the wheel) will stay on 2 minutes, then turn itself off? Restart the engine, same thing.. couple of minutes and shut off.

I believe I will test voltage at plug, test vacuum and if both are good.. buy another servo! I've already invested 2-3 hours in this and I'm loosing the desire to trouble shoot, time to start replacing stuff until I hit pay dirt!