Cruise control does not work when outside temperatures reach seventy degrees and above

Tiny
BRIAN K CONNER
  • MEMBER
  • 1996 FORD F-150
  • 4.9L
  • 6 CYL
  • 2WD
  • MANUAL
  • 184,000 MILES
Cruise control works fine in mornings or in cooler weather but when it’s in the high 70s or 80s in the afternoon it doesn’t want to work. Help. Clutch safety switch has been replaced as well as the switch on the master cylinder.
Tuesday, May 25th, 2021 AT 5:59 PM

4 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
When the cruise control is not working, does the light in the dash come on but it just does not engage?

I suspect this is the case and if it is then this is most likely a servo issue which is what actually holds the throttle cable in place.

We can do two things. First we need to check and make sure it is getting proper voltage.

https://www.2carpros.com/articles/how-to-check-wiring

The wiring diagram is below. Next we can replace it and/or try and adjust it first. I attached this process below.

Let's run through this material and we can go from there. Thanks
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Wednesday, May 26th, 2021 AT 6:28 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Since it works when it's cooler, something has to be expanding and causing a loss of connection. When it doesn't work, does the horn work?

I attached the entire wiring schematic for the cruise control. I had to cut it into two parts to make it readable, but I did overlap so you can follow from one to the next.

The one thing that I'm questioning is the clock spring in the steering column. When it doesn't work, is there any indication that it is powered up but failing to operate?

Let me know.

Joe

See pics below.
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Wednesday, May 26th, 2021 AT 6:33 PM
Tiny
BRIAN K CONNER
  • MEMBER
  • 35 POSTS
I will check to see if the horn works when it doesn’t work and get back with you. I tried something yesterday morning and that was unplug the unit under the hood and plug it back in just to make sure it was getting a really good connection and it worked fine yesterday on the way home, but I will know more later on today.
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Thursday, May 27th, 2021 AT 1:40 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Very easily it could have been a connection issue. It's interesting that it is working since it was done. Let me know what happens. I'm interested in knowing.

Joe
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Thursday, May 27th, 2021 AT 7:20 PM

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