05 B4000- Replaced brake light switch now cruise doesn't work

[Ragnar]

05 B4000 Automatic. I replaced my brake light switch and now the cruise control doesn't work. The cruise light in the dash does not come on or engage cruise. It was working fine before I replaced the switch that is mounted on the brake pedal. Anyone have an idea what the problem could be? The brake lights work fine.

 

[RonD]

Could be a bad switch or connection

Brake light switch is TWO switches inside
One is regular 12v in and out for brake lights, 2 wires

Other is 3 wire switch, fuse 32 5amp(cab) for 12v in wire and also has a ground in wire
When brake pedal is up the wire Out of switch is a ground, it goes to cruise
When brake pedal is down Out wire is 12v, which shuts off cruise
If this Out wire has 12v all the time then no cruise
Or if its not a Ground no cruise

 

[Colin]

Brake switch for the cruise is on the master cylinder

 

[RonD]

Yes, and also on the brake pedal switch
And in some years there is a vacuum valve on the booster end in the cab that releases vacuum in the cruise modulator so releases throttle plate
Usually a few "disable cruise" devices on any vehicle with cruise control, redundant safety thing



In new vehicles they have "radar" to shut off cruise, lol, but I WANT the flares as well, now that would be cool
I mean other drivers on the road are "kinda like" missiles, having some flares shooting off to distract them to avoid a collision should be a no brainer

 

[Colin]

My bad, should have realized there'd be redundant inputs

 

[Ragnar]

Could be a bad switch or connection

Brake light switch is TWO switches inside
One is regular 12v in and out for brake lights, 2 wires

Other is 3 wire switch, fuse 32 5amp(cab) for 12v in wire and also has a ground in wire
When brake pedal is up the wire Out of switch is a ground, it goes to cruise
When brake pedal is down Out wire is 12v, which shuts off cruise
If this Out wire has 12v all the time then no cruise
Or if its not a Ground no cruise

I replaced the brake light switch with a new one "again" hoping it was just a bad switch. Also checked and replaced the 5amp fuse in slot #32. brake switch (Logic) in the manual. Took it for a drive and still no cruise. I don't understand why the cruise worked with a bad switch and now it won't work with a new switch. Just to help you understand why I replaced the switch in the first place was because the truck would sometimes not shift out of park after starting. I posted that issue in here back in May 8th

B4000 shift lever stuck in Park

and was told in there to try replacing the shift solenoid on the steering column. That didn't work! Next I was told to try the brake light switch and check fuses. Now, here we are. The brake light switch seems to have rectified the shifting out of park issue (for now), but now the cruise doesn't work. So, as Colin has just posted, the brake switch for the cruise is on the master cylinder. Is this my next attempt at fixing the cruise issue?

 

[RonD]

I wouldn't replace the deactivator switch(on master) just use an OHM meter on its 2 contacts, should be Closed(0 ohms) when brake pedal is up, and Open(infinite ohms) when pedal is pressed

I should have looked at ABS diagram, it also uses the 3 wire part of brake pedal switch so would have had ABS light on if that part was bad

There is also a Fluid Level sensor on master, 3 wire, thats not the Deactivator switch(2 wire)

 

[Ragnar]

I wouldn't replace the deactivator switch(on master) just use an OHM meter on its 2 contacts, should be Closed(0 ohms) when brake pedal is up, and Open(infinite ohms) when pedal is pressed

I should have looked at ABS diagram, it also uses the 3 wire part of brake pedal switch so would have had ABS light on if that part was bad

There is also a Fluid Level sensor on master, 3 wire, thats not the Deactivator switch(2 wire)

Thanks for all the good info RonD. The only other thing I can think of would be to use a genuine Ford brake light switch, instead of an aftermarket switch, which is what I have used(Carquest). Although i am going to check the deactivator switch with an ohm meter first. I've never used an ohm meter before. How is the test done? Do I have to unplug the switch to get to the switch contacts?

 

[RonD]

Set Meter to lowest OHM setting, usually 200, unless it just has one OHM setting

Touch the 2 probe tips together, should see 0 ohms, a direct connection
Separate the probes and should see 1 or N/C(no connection)

i.e. if you put 1 probe on battery negative and the other probe on any metal part in engine bay you should see 0 ohms, or close to 0, depends on the "scale" selected

OHMs, in this type of test are just used to test if things have a good connection, like a fuse, if its good 0 ohms between contacts

The Deactivator switches 2 terminals should be connected together with brake pedal up, so 0 ohms
And N/C with brake pedal pressed down


OHMs are also used to test devices like solenoids or light bulbs, things that have a Factory Specification, like 20-60ohms, or 3 to 6 ohms, N/C here would mean bad part, or higher ohms than spec as well

 

[Colin]

Or some multimeters have a continuity tester. When the two leads touch it will beep, with the switch closed the meter should beep if the leads are on the switch contacts

 

[alwaysFlOoReD]

Don't use ohm setting on a live circuit (with power running thru the wires).

 

[Ragnar]

After determining that the cruise deactivation switch was faulty, I replaced it with a new one today. Still no cruise control. I did test the plug in, prior to installing the new switch and there was power going to it. So I'm still thinking that the issue is with the new brake light switch that i replaced last week. By replacing that switch, the not being able to shift out of park issue I was having was rectified. But now the cruise isn't working. I'm just not sure where to go from here.

 

[RobbieD]

Long shot, but I don't see it mentioned: are your tail light bulbs stock incandescent types, or are they aftermarket, such as LED?

 

[Ragnar]

Long shot, but I don't see it mentioned: are your tail light bulbs stock incandescent types, or are they aftermarket, such as LED?

Good question. When I bought this truck a year ago it had two LED lamps mounted on the bumper which are used as backup lamps only. The original lamps are incandesant brake, sinal and park lights. Attatched picture if of similar LEDs that are mounted on my bumper.

 

[RonD]

The brake pedal "sensor"(part of brake light switch) is 3 wire, 12v, ground, and out to devices
The out to "cruise" needs to be a ground or no cruise

ground---------sensor--(out)------------------------------cruise
12v-------------/

When brake pedal is pressed the sensor wire changes to 12v which disables cruise
But cruise can not be enabled until that wire is a ground again

So its not just a 12v on/off switch like brake light switch
It 12v or ground sensor