NoSparkplugs

So now that I have some extra time on my hands and a shop thats clear enough to put the truck in, I want to get to the bottom of my cruise control issue. The last time it worked it was surging like mad and then quit for good. I've checked the following:
-fuse is good
- servo seems to be ok
-No blown fusible links that I can see
- VSS is good, pulled part of it off and cleaned it up. Speedo works like it should

So today after reinstalling my front driveshaft (new u-joints) I decided to look under the dash and see what I could possibly find. I ended up finding a 6-pronged box and I took it out and opened it up to find a whole swack of dainty wiring. After double checking the wire colours I'm pretty sure this little box has something to do with the CC. What is it and what does it do? I was tempted to run off to the dealer and buy another one but I have a feeling that this certain part is made either of unobtainium or dentthewalletide.

Any suggestions is greatly appreciated

Lucas

NoSparkplugs

Anybody have any insight?

angelfire7

I thought Wannadeisel said something about the TPS in a simmilar thread awhile back. My aftermarket CC needed a micro switch at the brake. Might check for good vacuum also. Just my .02

Boatnik

My crusie control was surging badly too. It wound up being the plastic check valve at the top of the brake booster. The small hose barb to the cruise solenoid was broke and hanging on by a thread. I replaced it with one from the "HELP" cards at Advance.

NoSparkplugs

Well I went out and checked it again, I do have vaccuum so I don't think thats the problem. I didn't see anything broken around the brake booster unless I missed something (pic Mr.Boatnik? ). I really do think its something electrical. I can't see it being the PCM, since everything else works except the RWAL.

I did notice some sort of box on the side of the fender towards the cab. It had a vaccuum line spliced into the cruise vaccuum line to it and a 2 wire connection. Some sort of sensor I guess?

Boatnik

I don,t think I have a pic of the little "Christmas Tree" on the front of the booster. It is a plastic series of hose barbs. One large directly from the vacuum pump and three small. The one leading to the cruise control was the culprit in my case. If it isn't electrical, you may have a hole in the diaphram on the cruise module. It doesn't take much of a hole to give problems. I assume that your speedometer is working OK.
The device on the fender is the pressure switch that turns on the "Brake" warning light when vacuum gets above 8 inches Hg.

wannadiesel

On the '92 and '93 trucks the PCM runs the cruise. Sounds to me like you found the wiper delay box.

92DuallyCTD

Yeah, I think he found the low vacuum sensor for the brake system warning light(Hi Dave!). My cruise doesn't surge, but in checking things over, I noticed the slide fitting(?) on the cable end where it rests next to the throttle cable was almost binding for some reason. I just disassembled it, polished up the sides a little with emery cloth and WD-40'd it. You might check if your cruise cable may be binding? Then of course all the vacuum hoses(check the full length too, not just the ends) for any splits/leaks. Hope you get it straightened out, I'd hardly be able to drive at all w/o cruise!(I'm so spoiled...or is it lazy? Hmmmmm) ;-)

NoSparkplugs

Trust me, I'm going to fall in love with my truck again once I get the cruise working. Ever driven 4.5 hours, half of that in the mountains, with no cruise control? Not fun by any means . Tomorrow I'm going to do a very indepth lookover of the whole system and look for any holes in the lines or servo.

Falcon1

Clock spring.

Greg

dpuckett

Switches on the wheel are also notorious for failing. I got my cruise servo cable clipped back up, and had cruise one time, but the next time I used it, I couldnt get anything. I wasnt getting any power to the servo either.

Daniel

bigragu

Maybe we ought to offer a prize to whoever finds the fault, 'cause I'm in the same boat. Here is what I have done:
1. Vac is good-very good
2. Having the benefit of owning 2- 1st gens of the same year, I am able to swap out parts to check out what is faulted from one truck to the other. Servo is good, along with switches on steering column.
3. It is not the speed sensor that is mounted on the tranny or the NP205 for 4x4. tried that last weekend.
4. Linkages are adjusted per FSM, and the cable to the servo is solid, so that is done.
4. Only thing left on my end is the clockspring, brake/stop lamp switch at the pedal, and electrical between servo and switches. If anyone beats me to it, please pass it on! How the heck does a clockspring go out, anyway??

Jschlachta

Another thing concerning the surging is that the Cruise control is adaptive. If you set the cruise with foot off the gas it will think there is slack in the cable and cause surging. All data said to program you need to set cruise with at constant speed. need to do it like 20 times or something. I will post info from alldata.

Jschlachta

PCM - Surging With Cruise Control Engaged

9234chrysler01
NO.: 18-05-92

GROUP: Driveability

DATE: Jun. 15, 1992

SUBJECT:
Vehicle Surging When Vehicle Speed Control System Is Engaged

THIS BULLETIN APPLIES TO DIESEL ENGINE EQUIPPED VEHICLES.

MODELS:

1992 (AD) Ram Pickup/Ram Cab & Chassis

SYMPTOM/CONDITION:

The vehicle exhibits a surging when the speed control system is engaged at highway speeds. This condition may be caused by the calibration of the Powertrain Control Module (Single Board Engine Controller). Vehicles exhibiting this condition should have the following repair procedure performed.

PARTS REQUIRED:

1 Powertrain Control Module (Single Board Engine Controller)
Manual Transmission 56027081
Automatic Transmission 56027083

1 Authorized Modification Label 4275086

REPAIR PROCEDURE:

This bulletin involves replacing the Powertrain Control Module (SBEC) with a recalibrated module.
1. Replace the Powertrain Control Module (SBEC) as outlined in the 1992 Rear Wheel Drive Truck Service Manual, Publication Number 81-370-2108.


2. Type the required information on the Authorized Modification Label, as illustrated, and attach near the VECI.

POLICY:
Reimbursable within the provisions of the warranty.

TIME ALLOWANCE:
Labor Operation No. 08-19-91-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 Hrs.

FAILURE CODE:
AM - Authorized Modification

Copyright © 2007 ALLDATA LLC
Terms of Use

Jschlachta

Speed Control - Surge at highway Speeds
NO.:
08-07-93 Rev. A

GROUP:
Electrical

DATE:
Mar. 19, 1993

SUBJECT:
Speed Control Surge

NOTE:
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 08-07-93 WHICH SHOULD BE REMOVED FROM YOUR FILES. ALL REVISIONS ARE HIGHLIGHTED WITH **ASTERISKS**.

NOTE:
THIS BULLETIN APPLIES ONLY TO FOUR WHEEL DRIVE VEHICLES EQUIPPED WITH THE CUMMINS DIESEL ENGINE.

MODELS:

1992-93 (AD) Ram Pickup/Ram Cab Chassis

SYMPTOM/CONDITION:

Some vehicles may exhibit a speed variation at highway speeds while the speed control is engaged.

DIAGNOSIS:
1. Perform the speed control system test as outlined in Section 8H of the service manual. If no problems are found during the test, proceed to step 2.

2. On 1992 vehicles verify that the vehicle is equipped with the correct speed control servo and cable for the Powertrain Control Module (SBEC) that is installed, Refer to the chart below and make sure that the Powertrain Control Module, servo and cable match.

POWERTRAIN CONTROL MODULE REFERENCE CHART

SBEC Part No. Servo Part No. Cable Part No.

56027570 53007954 (Zemco) **4428787**
56027571 53007954 (Zemco) **4428787**
56027572 53007954 (Zemco) **4428787**
96027573 53007954 (Zemco) **4428787**

POWERTRAIN CONTROL MODULE REFERENCE CHART CONT'D

SBEC Part No. Servo Part No. Cable Part No.

56027081 53009315 (Eaton) **52078330**
56028082 53009315 (Eaton) **52078330**
56027083 53009315 (Eaton) **52078330**
56027084 53009315 (Eaton) **52078330**

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.

PARTS REQUIRED:

1 Speedometer Drive Gear 3732038

REPAIR PROCEDURE:

Replace the speedometer drive gear using the procedures outlined in Section 21 of the Rear Wheel Drive Dodge Truck Service Manual.
POLICY:
Reimbursable within the provisions of the warranty.

TIME ALLOWANCE:

Labor Operation No. 21-97-10-91................................0.6 Hrs.

FAILURE CODE:
58 - Internal Defect

Copyright © 2007 ALLDATA LLC
Terms of Use