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]

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.

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]

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

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]

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.

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]

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.

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]

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

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]

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.

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]

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.

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]

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.

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