Trying to get the cruise control to work...1985 F150

[LastDeadLast]

So as some as you know, I'm working on getting my new F150 back up and going.  I've now got the items fixed that can kill me or leave me stranded, so now I'm focusing on other items.

I've noticed that the cruise control has never worked and I'm just now starting to look at the issue.  I really haven't done much yet but I did notice something:  In an effort to fix an issue with the brake and hazard lights, I replaced the turn signal switch last weekend.  The signal switch turned out NOT to be the issue, but the new unit is installed.

I noticed today that the new switch is different than the old.  The old switch has two brushes mounted close to the steering rod while the new switch only has one.  NOTE:  The cruise control didn't work with the old switch either.  See the pics below..

Is that second brush necessary for cruise control?  I verified and I ordered the correct part (with tilt wheel).  Any advice is appreciated.

Thanks
-Shannon

[Gary Lewis]

We hashed this out in another thread, starting here, and the consensus was that the pin circled in red is actually not a brush but is the pin that cancels the turn signals.  So the other one, the one you don't have, must be the ground.  And w/o it the speed control should not work.

But does the horn work?  If that ground brush isn't there then the horn shouldn't work.  So if the horn works then you may have another problem.  And toward solving that you'll find almost everything you need to know about the speed control on the page at Documentation/Electrical/Speed Control.


 

[LastDeadLast]

Hey Gary, thanks for the reply:

Yes the horn works just fine.

Thats really strange.  I've checked pictures pics of turn signal switches online and none of them with a tilt-wheel have the extra ground brush (at least that I can find), but it looks like I can swap that center ring to the new switch if I need to.  (BTW, I purchased this switch from LMC)

So I looked at the old switch and indeed the brass colored brush does ground against the backing plate.  The other silver "brush" does not (same on the new switches).

As for horn, this is the back of my steering wheel horn/cruise control switch panel:



The black ground wire that I circled was pushed into one of the holes in the steel frame of the steering wheel (see pic below circled red).  I have no idea if that's correct, but that's the way it was.  My assumption is that the horn is getting its ground with that?   OR is the actual steering rod insulated from ground?  Based on your other thread, I did not check if the horn worked with the key on so I suppose it's possible that the ignition switch is grounding the steering rod.



Is there a way to actually test the cruise control switches mounted on the steering wheel?  With one ground wire and two "control" wires and 6 functions.. (horn, cruise on, cruise off, cruise set, coast, resume), I'm struggling to understand how that works.

Hopefully this ranting post makes sense.

Thanks,
-Shannon

[Littlebeefy]

There is a test for the switches on the wheel in the EVTM. Go to the speed control troubleshooting section. You will be checking for changes in resistance when you press the buttons. They should change to prescribed increments.

Remember that the cruise system requires vacuum. Check your vacuum lines and also ensure that your vacuum dump on the brake is not engaged when the brake is released.

[Littlebeefy]

Also, before you bother dealing with any speed control electrical, just make sure your horn works. They share a ground so that is a good indicator.

[LastDeadLast]

Thanks LittleBeefy,

I'm doing a little research in the 85 shop manual and I think I've found what the deal is.. apparently that little pin is added to the regular signal switch.  See the pics below:



and



I wonder if that pin is moved to a new switch?  At any rate, I can't find a new pin anywhere online, so I think I'll put my old switch back in and start my cruise control debugging from there since I KNOW I need that little pin.  I'll start with testing the horn with the key on and off.

Thanks again,
-Shannon

[grumpin]

They also show that wire going into the hole in the steering wheel.

I was sure it did, but wanted to see if someone else spoke up about it.

[ratdude747]

Note for future readers:

They also share power too via the +12V standby voltage present on the non-ground side of the horn switch (via the horn relay coil). The "cruise on" is a +12V switch, and to save a wire/slip ring connection, they source it from there, the idea being that if you're not going to honk the horn and turn on cruise at the same time.

This also means that if you blow the horn/lighter fuse, you effectively lose cruise as well (since you can't give it the On input to activate the controller). This is also why cruise control trucks have a horn relay and use the horn switch as a ground switch, while non-cruise truck have no relay and +12V reference the horn switch, all while using the same two-contact slip ring (brush and rings). And why cruise adds a grounding brush.

[Littlebeefy]

Is the ground brush removable from the old unit and transferable to the new unit?

There is no wire there so I'm trying to figure out what this ground brush is doing that the bolt holding the steering wheel on isn't doing. Aren't they both just creating an uninterrupted connection between the steering wheel hub and the column for ground?

I'm very curious if that missing ground brush is actually causing a problem. I don't have one and my horn works fine. So is there somehow a separate ground that isn't reflected on the diagram? That doesn't seem possible without a wire somewhere.

[LastDeadLast]

So I testing the horn with the new switch WITHOUT the ground pin.  Horn works with key on and key off.

I'm going to start the cruise control debugging process outlined in the shop manual to see how far I get.  If the switch isn't working, see about either figuring out how to swap the pins or just install the old switch.

-Shannon

[Gsmblue]

I have 2 trucks that the speed control is not working on. So will be following your journey with great interest.

[Littlebeefy]

I am really, really curious about this. I had a broken turn signal switch so I pulled it apart and took some photos. Here is that little ring from the inside of the switch. The turn signal cancel and the ground in question:


Here is the underside of that ring. You can see the backside of the ground sticking out. It’s spring activated and stays in contact with the metal plate in the middle of the switch:


Here is the pin after I pulled it out completely:

[LastDeadLast]

Chad,

Do you think the pin could be pulled out without destroying the switch?  I'd like to preserve my old one if possible.

-Shannon

[Littlebeefy]

The one I took apart had the pin jammed in so I had to cut underneath it to get a grip on it to pull it out. If it were not jammed in and it looked like yours, I think it would have pulled out with just a jiggle. There isn't really much holding it in there.

[LastDeadLast]

Thanks Chad,

I was able to yank out the pin and install it in the new switch, it wasn't a very snug fit, but I think the steering wheel will hold it in there just fine.

One thing to consider.. you need the steering column bolted in to test anything.  It gets ground from the mounting plate from the dash.  Ask me how I know.    I about drove myself crazy when I couldn't get the horn working and finally just gave up for the day until I thought about the ground last night.

I THINK I might've fixed the cruise control:  I looked at the dump valve and it had been shoved back so that the plunger was always open.  I adjusted it up to the brake pedal so that it's completely closed with the brakes not being used. There still might be other issues to deal with but this one is fixed.

I haven't been able to test drive it yet.  I have the dash apart waiting for other parts to come in.  Hopefully, by the end of next week I'll know.  I'll update the thread appropriately.

-Shannon

[LastDeadLast]

Cruise control fixed!!!!  Sorry it's been a while since I posted, but life and all.  

So just to update and close this thread:  The brake pedal dump valve did not fix the cruise.

I was watching a video on how to use the old Rotunda Cruise diagnostic tool (YouTube link) and this guy happened to mention that the Ford Cruise control might not work if you have LED brake lights.  Well I do.  Just for kicks, I popped in a couple of Sylvania Silverstars and BOOM!!  I now have cruise control!

Hopefully this helps someone in the future.

I'm pretty sure I still have a vacuum leak somewhere.  But thats for another thread.

Take care all,
-Shannon

[kramttocs]

Thanks for reporting back.
Another similar oddity I've seen firsthand is where cruise works but then using your turn signal kills it. Also due to led bulbs.