Wednesday, July 17, 2013

Cruise Control Stop Working?

2001 Durango Cruise Control Light Stop Working


2001 Durango with the 4.7 V8 2wheel drive. What would cause the cruise control to stop working all of the sudden?

Previous Issues:
Had A/C issues with not blowing cold, pumped out the system and recharged also find the vacuum leak that has been keeping the check engine light on and fixing. The cruise light comes on when turned on but will not set.

Already Checked:
Have checked all the fuses  all are good. Any ideas?

More Suggestions Required:
Also would like opinion about A/C. Was blowing warm up front, but cooler in back( rear A/C), was recommended to vacuum system and recharge (in case had any air in it), did just that. It blows cold on both ends now while going down the road but still seems to struggle while idling or stuck in slow traffic. What else can I do check?


POSSIBLE TROUBLESHOOTING SOLUTIONS:


  • There are quite a few things that will stop cruise from working. The cruise switches, brake switch, cruise servo, wiring, throttle position sensor, MAP sensor, trans related or some ABS related issues will prevent cruise from working. 
  • If the cruise stopped working after some work was done under the hood then the first thing to check and confirm is the servo has vacuum, a line may be off or pinched. With the engine running remove the vacuum line from the servo and make sure it does have vacuum.
  • The next thing to do from there would be checking for fault codes. Many of the possible causes will set a fault code, including some causes that may seem unrelated. If vacuum is ok and no codes are set then monitoring some data on a scan tool may be necessary to see why it isn't working.
Cruise control,vacuum lines and servo

There are several possible problems with the cruise control system. 1- loss of vacuum to the servo. The servo pulls the cable that opens the throttle . It is located under the battery tray. The servo can get battery acid on it. The acid can eat a hole in the servo or- most likely the vacuum line that feeds the servo.

There should be a strong vacuum with the engine running at the vacuum line to the servo. If no vacuum if felt- back trace the line to the reservoir located under the cowl on the passengers side.

There is a vacuum line that connects the tank with the vacuum supply from the engine,. The other problem we see often is the clock spring assembly in the steering wheel has a bad internal circuit,This part connects the switches wiring through the column to the under dash wiring harness. And the switches can become dirty and not make connections,. A scan tool is used to monitor the switch output from the steering wheel controls, Some times pushing the switches will clean them up enough to work for awhile.



The A/C Problem 
The original a/c problem sounds like a bad front expansion valve, but I wouldn't replace it unless you start having a temperature difference between front and rear again. If it cools ok when driving but warms up at stops that is a sign there is little or no airflow over the condenser because of a fan issue. Depending on build you may have just an engine driven fan, just an electric fan or both. Whichever system you have, it sounds like the fan isn't turning on or engaging while you are stopped.

Getting all this Possibilities Checked And Confirmed will Help.
Thanks.

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