cruise control problems?

[93MTXSHO_STUD]

A while back I would set my cruise control and the car would pulse accelerate. It would be set to the speed i want, then it would slow down 5 mph or so, then speed back up to the speed. Then recently the cruise control doesnt even work at all. What could this be? I am totally cluseless when it comes to this.

 

[Frankiek3]

Make sure that the cable did not come lose; it is near your TB

If it is still there I have heard cruise control will be lost from either a vacuum leak or the VSS vehicle speed sensor. I am not sure on the VSS though.

 

[rangerj]

The cruise control can also be lost if its wire in the clockspring is "open". Does your horn work? How about the air bag? These are the three things connected through the clockspring. This is just another possibility to go along with the others mentioned above. rangerj

 

[93MTXSHO_STUD]

the horn works fine, the air bag light doesnt come on so i dont think thats the problem. How do you test to see if the canister has pressure? Could the cruise control canister be bad?

 

[MeSHOYouHow]

my horn and air bag worked fine but the wire for the cruise was broke in the clock spring.

 

[Rockledge]

Testing for Cruise Control Diagnostic Trouble Codes (MTX)

I did not know this until recently, but the "Integral Vehicle Speed Control System" or IVSC on the Gen II MTX (it’s not the same thing on the ATX, nor am I sure whether Gen I setup is the same ) has monitoring abilities and can actually set DTCs which the PCM will store in memory and can be retrieved, just like regular engine management trouble codes. My Ford Manual indicates the following, which I am both quoting and paraphrasing, and also adding my own 2 cents:

Key On, Engine Off and Engine Running tests can check the IVSC system by testing its functional capability and verifying that various sensors and actuators are connected and operating properly. The KOEO and KOER IVSC tests are functional tests which only detect concerns present at the time of the Self Test.

To activate KOEO IVSC test, do the following:

1. Place transmission shift lever in PARK.

2. Hook up your multimeter in accordance with the regular EEC-IV code-pulling procedures (see http://www.dalidesign.com/hbook/eectest.htm)

3. Turn ignition switch to RUN position.

4. Within 10 seconds, press speed control ON switch.

5. Press speed control OFF, COAST, ACCEL, RESUME buttons; tap brake pedal once.

NOTE: Do not depress throttle during KOEO self-test.

6. Observe and record all Diagnostic Trouble Codes indicated.

DTC 452 = VEHICLE SPEED SENSOR (VSS) PROBLEM.
(Note: This code is actually stored by the regular EEC-IV monitor(s), not the IVSC system monitor. Hence, it’s probably a good idea to run the codes in the regular manner before doing the IVSC system test in order to see if this VSS code comes up).

DTC 453/454 = DOES NOT HOLD SPEED DURING DYNAMIC TEST
Possible Causes:
- Speed control servo.
- Vacuum hose connections.
- Speed control vacuum reservoir
- Speed control vacuum valve.

DTC 455 = SPEED DOES NOT INCREASE DURING DYNAMIC TEST
Possible Causes:
- Actuator cable.
- Vacuum hose connections.
- Speed control dump valve adjustment.
- Powertrain control module.
- Speed control vacuum reservoir.
- Speed control vacuum valve.

DTC 456 = SPEED DOES NOT DECREASE DURING DYNAMIC TEST
Possible Causes:
- Actuator cable.
- Throttle shaft and linkage.
- Throttle position sensor (TPS).
- Powertrain control module.

DTC 457/458/459 = SPEED CONTROL SWITCHES
Possible Causes:
- Speed control actuator switch assembly.
- Air bag sliding contact.
- Wiring harness.
- Powertrain control module.

DTC 567/568 = SERVO SOLENOIDS
Possible Causes:
- Servo vent solenoid.
- Servo vacuum solenoid.
- Circuits SOL+, SCVNT, and SCVAC.
- Powertrain control module.

Happy Holidays! :wave:

 

[Slo-Sho]

The MTX and ATX cruise control systems are two totally different animals. One being vacuum operated and the other electrically controlled.

 

[Rockledge]

FWIW, I just noticed that the daliddesign site also has similar instructions on how to pull cruise control codes:

http://www.dalidesign.com/hbook/cruise.html

As can be seen in the link, two-digit trouble codes can also be set and displayed from the same tests which seems to confirm that the tests are also applicable to the Gen I MTX cruise controls sytems.

 

[93MTXSHO_STUD]

1. Hook a tester up to the EEC IV connector, but leave the trigger unplugged (or test switch off on some testers). Try to position the tester or light so you can see it from the driver's seat.

This test I am clueless how to do? I think the EEC connector is that thing next to the ABS test thing right on the plastic part that goes over the engine. Is this the same connector that is used when testing for engine codes? I have a manual, and I heard the manuals are totally different from the autos well at least the electrical diagrams are different. Could someone elaberate on this issue. If there is a way to test the cruise control and get codes I would like to know. I really need it when I go from Austin to Lubbock. 360 miles of straight rodes needs cruise control.