ok, That maybe it. I'll get one from FORD.

 

They should have them on the shelf. 1L1Z-9F924-AA if memory is correct

 

Cc is working again. Thanks Guys

 

New part $30.
Advice $300.
Put check in mail.
Good luck.

 

Thank you,
Keep my tab open, this baby is running strong at 184980.

 

So it was the switch? And a Motorcraft one fixed it?

 

Correct. The (secondary) switch on the master cylinder. An advance auto switch worked for two weeks the failed to hold speed.

 

Well that didn't last very Long. That's what she said about this Cruise control fix. It stopped working again. So Motor craft switch is 30 days better than Advance ? What could it be ?

 

Maybe you just got a bad switch from Ford, mine has been in for several years now with no issues.

 

 

I will bet the master cylinder pressure switch is being opened due to rising pressure for some reason.
If you put a shunt connection across the switch plug and CC holds over an extended time period , it should prove the cause.
If that should be the case, the master cylinder may need to be replaced.
.
The master cylinder switch is a special design originally developed by Texas Instruments company, years ago.
It has to be sensitive to low pressure to open the contacts and and standup under very high pressures when brakes are applied normally, that ranges in the hundreds of pounds pressure.
As we find, not every company pays attention to the production quality and specs for the switch application they put out for vendor sale.
Good luck.

 

Snow on the grownd. Now CC is working again. Inop when the outside temp warms up to 60's. I'll try the shunt, BG.

 

Thanks Bluegrass for all of your help. (happy new year) It's working more than not. The Good news is Santa somehow stuffed a 2012 F-150 Raptor down the Chimney. So My 99 F-150 Lariat 4X4 is (Tear in Eye) going on a page of thrifty Nickel. Good Luck and again thanks.

 

I have this problem but it only disengages when it's cold outside (40 degrees or less). Seems to be interior heat related but I am not sure. I have not checked anything out yet. It cuts off and I cannot resume or set. Wait a while and then it will come on, sometimes for an instant, sometimes for a few minutes. Turning it off via the on/off switch seems to make it start working again sooner. It's usually out for 3-5 min. I've tried turning the heat off, which worked for a while, but does not work always now. Any thoughts appreciated.

 

See post #26.