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Discussion Starter · #1 · (Edited)
Hi all,

So, I've been using my cruise control for the last several years and it's always worked great.
Then suddenly, poof, it died. I have no cruise. FWIW, the horn still works, as I know they're on a joined circuit.

On my Sniper, I can see the TPS, and as I drop speed, it sits at 0%. The CC is just doing nothing.

Things I've checked:

  • Gone through all the fuses and verified they're still good.
  • Pulled the steering wheel and cleaned all the contacts.
  • Checked the cable at the throttle and verified it's connected.
  • Disassembled the servo and verified that the cable is still attached to the servo.
  • Checked that the Brake On Off signal going into the speed control module switches between 0 and 12v when the brake pedal is pressed/released.
  • Checked the brake pedal vacuum switch and verified it adjusted properly.
  • Checked the brake pedal vacuum hose at the servo and verified it's holding vacuum.
  • Checked the vacuum line from the engine to the servo and verified it has vacuum.

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My cruise control is just dead.

I'm assuming at this point that either the horn pad isn't working, the servo died, or the actual speed module has died. Maybe something else I'm not thinking of but I'm not sure what yet.

Does anyone know how to test these? Other things I can check?

I have a wiring diagram, so I don't need that posted up.
But what I don't know is how to test these systems when the vehicle isn't moving.

Thanks all, this has me stumped.
 

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Discussion Starter · #2 ·
Just checked the horn pad and verified all the buttons are working

I grounded out the blue wire and then pressed each button:

Key off (no buttons pressed): 0v
Key on (no buttons pressed): 8v

Set: 4.6v
Coast: 1.5v
Resume: 6.4v
Cc on: 12v
The only one that didn't do anything was the off button, but that's never worked as long as I've owned it.
 

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Discussion Starter · #4 ·
I'm wondering if I might have to.

I spent the afternoon doing more tests. Unplugged the plug from the cruise control amplifier and went through it with a volt meter and did all the tests that were written out in my shop manual. Every test passed. The voltage from the fuse block, the brake on/off switch, the resistance between the signal wire and ground when all the buttons were pressed, power when ON was pressed, etc. etc. All tests passed.

Every single test has been successful and passed the tests. Except it still just doesn't do anything.

So yeah, I think the next step is unplugging the servo and hooking a voltmeter to it and seeing if it's getting signals while I'm driving and pressing buttons.
If it's receiving signals, but not working, the servo is bad.

If no signals are being sent, the cruise control amplifier is bad.

Unless someone has any other ideas.
 

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Just be careful, you might want to disconnect it if driving regularly, until you get it straightened out.
I had a cruise control quit working on an f250 I used to have, and it went crazy one day, while I was driving in afternoon traffic. It started randomly just throttling up the engine. Still not quite sure how I got it home without killing anybody. It did this at a red light, and I had both feet on the brake pedal, my ass off the seat, trying to keep the truck from pushing the car in front of me out into cross traffic.
 

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Discussion Starter · #6 ·
Wow, I've never heard of anything like that happening before. That sounds like a horrible situation, glad you were alright.
 

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The cruise control on the 94 - 96 has always been a bit hokey
In fact, the switch by the master cylinder leaked and caused many of them to catch fire
When you took your bronco to a dealer they hooked up this 'bypass' assembly that effectively disabled it
Then a yr or 2 later I think ford made a reliable switch that would not leak brake fluid
....I think thats how the story goes

Mine works kinda shitty on my '94 so I dont use it much
On the hiway its constantly surging up and down.....uncomfortably so
It can never zero in on the setpoint

So, to Gunfixr's point, be careful of the thing.
 

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Unless its just me, I think alot of these 'newer' Broncos (80 thru 96) are starting to come up with odd-ball electrical problems never seen before
Alot more than I have in years past anyway. Perhaps as they get older this will be more common.....
 

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Discussion Starter · #10 ·
Thanks for the link. The images they have in there are to the same shop manual I have in my garage, so I was able to go through the steps they have. This is the only part that I didn't have (and it looks like they don't either).

Font Number Art Circle Brand


I'm curious what shop manual they're referring to.
 
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Discussion Starter · #11 ·
The cruise control on the 94 - 96 has always been a bit hokey
In fact, the switch by the master cylinder leaked and caused many of them to catch fire
When you took your bronco to a dealer they hooked up this 'bypass' assembly that effectively disabled it
Then a yr or 2 later I think ford made a reliable switch that would not leak brake fluid
....I think thats how the story goes

Mine works kinda shitty on my '94 so I dont use it much
On the hiway its constantly surging up and down.....uncomfortably so
It can never zero in on the setpoint

So, to Gunfixr's point, be careful of the thing.
I've read of those issues on that era of Broncos. The catching fire thing was pretty bad for sure.

My cruise has always worked very well. The only issue I have ever had with it is that it won't pull the throttle more than about 45 - 50%, so I lose speed on hills unless I take over. But, I recently (as of yesterday) realized that might be because I have it hooked directly to manifold vacuum and not to the vacuum canister, so it probably didn't have the vacuum to pull any harder under acceleration since there was none coming from the engine.
Otherwise, it's been very good.

So this instant death with no direction is frustrating to say the least.
 

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Just be careful, you might want to disconnect it if driving regularly, until you get it straightened out.
I had a cruise control quit working on an f250 I used to have, and it went crazy one day, while I was driving in afternoon traffic. It started randomly just throttling up the engine. Still not quite sure how I got it home without killing anybody. It did this at a red light, and I had both feet on the brake pedal, my ass off the seat, trying to keep the truck from pushing the car in front of me out into cross traffic.
I had a '78 Bronco that did the same thing, but luckily on the freeway. I slipped it into neutral, hit the key and managed to get pulled over to the side without the power steering and somewhat limited power brakes. I disconnected the ball-chain for the CC and didn't use it after that.
 

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1982 Bronco XLT Lariat, 351W, C6; 1989 Bronco XLT, 302, AOD
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The cruise control on my '89 5.0 quit on a trip about two months ago. Turned out the cruise cable popped loose from the throttle cable. Reattached the cruise cable and everything is fine.

I also have problems with losing speed when going up a long hill with the cruise control engaged. I will try moving the vacuum line to the canister and see if that helps.

Good Luck with yours.

TB
 

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I had a '78 Bronco that did the same thing, but luckily on the freeway. I slipped it into neutral, hit the key and managed to get pulled over to the side without the power steering and somewhat limited power brakes. I disconnected the ball-chain for the CC and didn't use it after that.
I was going home from work, only had a couple miles to go. But when I got home, I removed the whole thing. I rarely took it on anything resembling long trips anyway.
 

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Thanks for the link. The images they have in there are to the same shop manual I have in my garage, so I was able to go through the steps they have. This is the only part that I didn't have (and it looks like they don't either).

View attachment 201904

I'm curious what shop manual they're referring to.
Ford video course 3701-007

Yo,
Have searched for that videoto no avail
Will try again later,
 

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I have found if the speed control system does not work at all but the input signals to the amplifier are good, i.e. power, switches,etc., the amplifier is bad. I have had erratic operation due to a rusted out speed control vacuum reservoir but when I replaced it the system worked just fine, even on longer uphill grades.
 
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Just be careful, you might want to disconnect it if driving regularly, until you get it straightened out.
I had a cruise control quit working on an f250 I used to have, and it went crazy one day, while I was driving in afternoon traffic. It started randomly just throttling up the engine. Still not quite sure how I got it home without killing anybody. It did this at a red light, and I had both feet on the brake pedal, my ass off the seat, trying to keep the truck from pushing the car in front of me out into cross traffic.
for this - all i can say is put that bitch in neutral. or kill the engine.


abandoned bronco - i read through this but didn' treally dive deep b/c i don't have real expertise to offer. however, i did run into a problem with my vss a while back. and, part of that issue manifested itself by preventing my cruise control from working.

now, it was a little different, because my issue was intermittent while yours was a sudden and complete break. but, what was happening is the vss signal was failing to get to the cruise control properly. the lack of vss signal to the cruise control kept the cruise control from working. and mine is a 96, so probably pretty different than you.

that's all i got. good luck!
 
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