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Exactly. Except I'm not convinced that the booster pulls the rod forward, I'd have to look at it closely to find out. I took my switch completely apart so I could see the contacts. They were fine. There is a plastic pin that pushes the contact arm that appears to be worn and this would require more travel for the switch to close. I could shim it but I can't think of a way to make sure the shim doesn't move.
I have been assuming that it is the pedal switch doing the work and not the secondary switch. I can attach a test light to see when it closes.
If you do take remove your switch make sure that you note the positioning of the plastic bushings and washers so that you don't waste time like I did.
Pushing the brake pedal harder is not a solution, it is the problem. This is my first Ford. All my previous vehicles with automatic transmissions have been GM except a few old Mercedes W123s. All of them have adjustments for the brake light switch. All of them I could tap the pedal to disengage the CC without an increase in engine speed. This also alerts drivers behind me that I am slowing down before the brakes actually engage. On this, and many other Fords, the brakes are engaged before the lights come on whether or not the CC is being used.
It's converter flash from the clutch disengaging. The cruise motor can not shut the throttle faster than the clutch unlocks so you get a flare in rpms. I have had this in most of my vehicles, excluding the manuals. But, even then if I stab the clutch I get a rise in revs.
Now, if you are able to depress the switch slightly without lighting the lights then it sounds like a dead spot in the switch. My clutch switch went out in the 95 and wouldn't allow it to start, however it would still turn off the cruise because there are two circuits actuated by the same rod. (I bypassed the clutch switch and tied into the horn relay go start because I was working too many hours and didn't have time to do the switch at that time lol) I'm not positive the brake switch is the same but it makes sense because I would think that running your flashers would shut off cruise and on my truck that is not the case.
If it is flash and the motor can't disengage fast enough that is still a design issue. In my book that is not acceptable. As stated in a previous post my GMs and Mercedes don't do this and they have adjustable switches to ensure that the switch closes before hydraulic pressure is built.
Are "most of my vehicles" Fords?
If you get a rise in RPMs when the clutch is pressed either the switch is out of adjustment or is the same design as the brake light switch.
The clutch pedal should actuate two switches. One to change states at the start of travel to signal the CC to disengage, and one at the end of travel to complete the starting circuit so that the starter motor will crank.
I'll test the flashers next time I drive the truck.
If ANY hydraulic pressure is required to light the brake lights, that means it's the PRESSURE switch on the master cylinder kicking in. That's a SECONDARY switch. Most likely that means that the PEDAL switch on the pedal arm in the cab has failed. You should be able to jam a snow brush or other such object between the seat and the pedal, and induce minimal pedal movement, to light the brake lights. If that's not happening, check that switch (with a meter).
No need for a snow brush around here. I do have a leg from a tripod to do this kind of testing. I tested the primary switch with a multimeter and it shows that it closes about the same place as my reflection test did.
If I really want to understand this I'll need two test lights, one for each switch.
I have a factory service manual for 1994 and it makes no mention of of the hydraulic pressure switch. The only mention of the pedal switch is in wiring diagrams or in drawings.
If you get a rise in RPMs when the clutch is pressed either the switch is out of adjustment or is the same design as the brake light switch.
No, 89 Caprice 700r4, 96 Blazer 4L60e, 97 Blazer 4L60e, 83 Cutlass Calais rwd 200-4r with lockup converter, 96 S-10 4L60e, my pops 02 HD with the 4L80e and uncles 01 7.3 powerstroke with the I'm guessing e4od. Both of my F Series have been manuals so cannot compare to an e4od.
That sounds a lot different from what you described in your first post:
What most people would call "tapping" the brake pedal won't slow down the truck. It should briefly flash the brake lights, unlock the torque converter and disengage the speed control, but it wouldn't be enough to give any hydraulic pressure to the brakes. So my questions and comments were based on the idea that you were seeing this when you just tapped the brake pedal.
If you are actually applying the brakes and the brake lights aren't coming on, that sounds like at least a gummed up brake light switch. I'd pull it off and try to clean it up, or just replace it with a new one.
I don't see that much difference. I didn't say that I felt the acceleration because I thought it was a minor detail and implied.
Tapping is what I was expecting to give me the desired results which is feeling the CC disengaging. I was pressing on the brake pedal expecting to feel the CC disengaging but the CC applied more throttle and I had to press further to get the switch to close thus disengaging the CC.
The switch was fine before I took it completely apart for inspection and lubrication which made no difference.
I think we are getting into an argument over semantics which is not productive or help solve my problem which is getting the pedal switch to close before hydraulic pressure is increased in the brake system.
Well, for 6 bucks for the cheap one, is put a new one in and see if there is a difference. If not, you are out 6 bucks and you know to look somewhere else. If it works rock it till it quits then go for the 23 dollar motorcraft switch.
If you had to press further and apply pressure to disengage the CC, it wasn't the pedal switch that closed. It was the pressure switch that eventually closed. The pedal switch still isn't working. The contacts may be closing, but unless there's power in the circuit, it still won't light the brake lights, or disengage the cruise. Test the brake pedal switch circuit end to end.
The brake on/off switch is a bit of a wacky design. My old 1992 F350 acted very similar when touching the brake pedal. Many times the truck would slow down when lightly pushing the brake pedal but the brake lamps never activated. I replaced the switch with a Ford/Motorcraft brand but it never helped. My truck had the older vacuum assisted speed control. Getting the dump valve adjusted to coincide with the brake activation was a bear.
I did get some better results after replacing the brake booster. It created a very soft/spongy pedal. After replacing a bunch of other brake system parts the booster made the most difference in feel and performance. There have been some recent posts stating the later model 1996/97 master cylinder has a larger bore to increase pedal feel.
Since the switch acts like a pressure differential device that may be an option, although expensive proposition.
The issue with the brake lights not staying on when the pedal is slightly pressed while the vehicle is running seems to have been the case on all 3 of the 92-96 trucks we have had.
I attached a test light to each of the switches and got interesting results. There had to be considerable brake pressure for either test light to change states (in this case to change from on to off) thus indicate powering the brake lights. For example the pressure to hold at a red light was not enough to have the brake lights on neither was slowing down on a 45 MPH road to turn onto my driveway until the last few feet.
The test lights changed states at different times. Sometimes the pressure switch would actuate first, sometimes the pedal switch did and sometimes they would both come on at the same time.
The pedal switch test light got dimer half way through my drive. I measured 8 volts at the switch and was expecting to see 12 volts.
When I parked the car at home with the engine still running I saw that only the pedal switch would change states. Upon further investigation both brake lights were not turning on. I got results that I do not understand when probing the bulb and socket with a multimeter.
I'd really like to see drawings for these circuits.
My next step is to find a way to shim the pedal switch. Or should I install a normal switch. Or is it to get the brake lights working. God I hate this truck, but the 460 is fun to drive.
If I were to design and build a bracket to convert to a normal, adjustable switch, would anybody be interested in buying one.
I added a spring to the brake pedal switch on my 92 F250 years ago. Just as described, brake lights either wouldn't activate under light brake application, or would go out as pedal pressure decreased. Spring attached to the switch solved this.
I put a superduty brake switch on mine, without moving the boosters push rod the brake lights turn on.
Also I had the same issue with the brake lights on another truck of mine and it was due to air in the lines and improperly adjusted rear brakes (and probably seized front calipers).
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I do have a leg from a tripod to do this kind of testing. I tested the primary switch with a multimeter and it shows that it closes about the same place as my reflection test did.
