Intermittent Cruise Control

[cnijsse]

I have a Chinook Concourse sitting on a 2004 E350 chassis. My cruise control only works when it wants too. Sometimes it works great for miles until I turn the engine off (pit stop). Then it won't work for miles until I cycle the engine off and on again. The last time, I drove 350 miles and didn't risk turning the engine off at gas stops because it was working great.

I've replaced the column switches, but they were not OEM replacements. I've read about clock springs, pressure switches, etc., but this is an intermittent failure. I hate just throwing in parts without knowing which part went bad.

Any thoughts?

[noluck]

when it doesn't work, see if the horn works. if it does not the clocksping is failing.

[cnijsse]

Thanks Noluck. I'll give it a try and let you know what happens

[noluck]

sounds good

[cnijsse]

As you suggested, I tried a few short trips and my cruise control failed. When it did, I tried the horn and it worked great (much to the irritation of neighboring drivers).

I recently did a 400 mile drive. For the first 50 miles, no cruise control. I would try periodically, then suddenly it kicked in and worked the rest of the trip, even after stopping and starting the engine. Now I'm thinking that the pressure switch is hanging up and when it gets hot enough, it frees up and starts working.

Any thoughts?

[Blewett]

Dang the clocksping would have been an easy to find problem.

It could be a whole host of things but it sounds like a computer tied issue since it comes and goes when you cycle the engine. It could also be an issue with something that trips or triggers the cruise control computer/servos to stop/shutdown until restarted. Have you checked for codes?

If you don't have an ODBII scanner (most people don't) you can take it to most part stores and they can plug a scanner into the vehicles computer and look for codes. Good scanners can check for active codes and inactive codes. Your cruise control issue may show up in either category. Bring a pencil and paper to copy the codes as they are a jumble of letters and numbers. Then google the codes and see what comes up and/or post them here.

Also does the cruise control ever come back immediately after restarting the engine? You can (but probably not recommended) put your rig in neutral while driving on a straight stretch of highway and completely shut off the vehicle and restart it. --Note do not go to the off position just accessory position, wait for engine to die then restart. I believe most computers power down during the engine start up. Then see if cruise control works again. OR you can just stop at a rest area or off ramp.

Do you have any signs of a vacuum leak? Rough idling, hard brake pedal, slow acceleration, check engine light? The OBDII scanner should register a vacuum leak.

[cnijsse]

I don't show a Check Engine Light or any other codes on the dash. However, I'll take it in to see if someone with a scanner can see something.

The engine runs smooth and shows no indication of a vacuum leak.

Thanks for the suggestions.

[caconcourse]

My Cruise control was intermittent after working well for the first few years after we bought it (2001 Concourse). I replaced the control switches with a set from EBay which had a more positive switching feel and green backlit labels. At the same time, I traced the control wires under the hood to a three-pin connector right below the brake master cylinder that had been partially damaged by rodents. I straightened out the wires and taped over some exposed copper, and that combination fixed the cruise control completely.

[noluck]

Dang the clocksping would have been an easy to find problem.

It could be a whole host of things but it sounds like a computer tied issue since it comes and goes when you cycle the engine. It could also be an issue with something that trips or triggers the cruise control computer/servos to stop/shutdown until restarted. Have you checked for codes?

If you don't have an ODBII scanner (most people don't) you can take it to most part stores and they can plug a scanner into the vehicles computer and look for codes. Good scanners can check for active codes and inactive codes. Your cruise control issue may show up in either category. Bring a pencil and paper to copy the codes as they are a jumble of letters and numbers. Then google the codes and see what comes up and/or post them here.

Also does the cruise control ever come back immediately after restarting the engine? You can (but probably not recommended) put your rig in neutral while driving on a straight stretch of highway and completely shut off the vehicle and restart it. --Note do not go to the off position just accessory position, wait for engine to die then restart. I believe most computers power down during the engine start up. Then see if cruise control works again. OR you can just stop at a rest area or off ramp.

Do you have any signs of a vacuum leak? Rough idling, hard brake pedal, slow acceleration, check engine light? The OBDII scanner should register a vacuum leak.

there is nothing in the cruise circuit that will cause a check engine light

[cnijsse]

I finally found a Ford dealer that was willing to put some time into diagnosing my cruise control issues. Apparently the servo is hung up. They can't find replacement parts because they're "obsolete."

Does anyone know where I can source a new servo? I'm looking at scrap yards, eBay, etc. I need part no. yc2f-9c734-ab