Tail lights slow to come on
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Tail lights slow to come on
I have a 98 f150 that I don't drive often. I had it out tonight and realized the my brake lights wouldn't come on unless I pressed the peddle down hard. Does the switch work off of pressure? They used to come on as soon as I would touch the peddle. Any ideas would be helpful.
Lead Driver
Joined: Sep 2006
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Sounds like the brake light switch is sluggish.
Better tend to it becuse other funtions depend on this switch operation such as the Cruise Control kick off, converter lockup coming off in an Emg brake application etc.
The Cruise Control has a backup shut down using a pressure switch on the master cylinder.
Really you should only have to tap the pedal lightly to flash the brake lights and kick off the C.C. if the switch is good and adjusted correctly.
Good luck.
Better tend to it becuse other funtions depend on this switch operation such as the Cruise Control kick off, converter lockup coming off in an Emg brake application etc.
The Cruise Control has a backup shut down using a pressure switch on the master cylinder.
Really you should only have to tap the pedal lightly to flash the brake lights and kick off the C.C. if the switch is good and adjusted correctly.
Good luck.
Mountain Pass
Joined: Jun 2006
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From: Saskatoon, Sask
Quick search I did for the brake light switch on FTE
1999 Ford Expedition 4x4 - 99 expedition brake light switch
I would start with the switch. It sounds like it's getting worn out. The switch is a "Normally Closed" switch. Think of it like a button, but instead of turning on when you push it in, it turns off, and when you release it, it turns on. Backwards eh? That's how a brake light switch works. When the pedal is not being used it's pushing that switch, making sure it's off. Then when you push on the brake it released the switch to it's normal state, which effectively closes/completes the circuit. Then voila, brake lights come on. When you release the brake pedal it moves back against the stop, pushes the switch, and opens the circuit again, turing the lights back off.
Sounds like the switch is sluggish like Bluegrass 7 said. Could be jammed up with something, spring could be failing, or the contacts are screwing up. The harder you press the pedal shouldn't have any effect at all on the brakes lights. It's most likely just a delay you're experiencing. Check out the link. Thank P Madson for that.
1999 Ford Expedition 4x4 - 99 expedition brake light switch
I would start with the switch. It sounds like it's getting worn out. The switch is a "Normally Closed" switch. Think of it like a button, but instead of turning on when you push it in, it turns off, and when you release it, it turns on. Backwards eh? That's how a brake light switch works. When the pedal is not being used it's pushing that switch, making sure it's off. Then when you push on the brake it released the switch to it's normal state, which effectively closes/completes the circuit. Then voila, brake lights come on. When you release the brake pedal it moves back against the stop, pushes the switch, and opens the circuit again, turing the lights back off.
Sounds like the switch is sluggish like Bluegrass 7 said. Could be jammed up with something, spring could be failing, or the contacts are screwing up. The harder you press the pedal shouldn't have any effect at all on the brakes lights. It's most likely just a delay you're experiencing. Check out the link. Thank P Madson for that.
Hotshot
Joined: Jan 2004
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From: St Louis
The switch is a "Normally Closed" switch. Think of it like a button, but instead of turning on when you push it in, it turns off, and when you release it, it turns on. Backwards eh?
Don't take this the wrong way because we know you are trying to help, but if you don't know specifically how it works, it's better not to just throw stuff out that doesn't apply since you're just going to confuse the issue.
The problem is most like going to be a defective or mis-adjusted switch or a defective wire going to the switch. Please keep it focused.
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Posting Guru
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Yes & No. The brake light switch does not work off of hydraulic pressure, it is not a 'wet' switch like the Bad Old Days. However the switch does work by spring pressure.
The brake light switch is also not located under hood, on brake master cylinder, or brake fluid line. It is over brake pedal, under the dash, afixed to clevis at MC rod.
Have a '98 F150 & it has normally open brake light switch, that closes when brake pedal is moved less than 1/2" but it's spring loaded in such away that foot pressure shouldn't directly effect how much pressure is on the switch. The brake light switch works thru a relay that clicks somewhere under passenger side dash.
Have a '98 F150 & it has normally open brake light switch, that closes when brake pedal is moved less than 1/2" but it's spring loaded in such away that foot pressure shouldn't directly effect how much pressure is on the switch. The brake light switch works thru a relay that clicks somewhere under passenger side dash.
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Hotshot
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From: St Louis
The brake light switch works thru a relay that clicks somewhere under passenger side dash.
You're hearing the snap-action of the switch itself.
Posting Guru
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Perhaps "You're hearing the snap-action of the (brake light) switch itself." on your "98 f150".
However, I can assure readers that on my '98 F150 the brake light "switch itself" is silent, AND each time my brake pedal gets pushed down slightly I hear the unmistakable click of a relay closing off to the passenger side behind the dash.
Note that the click is a faint sound heard w/motor not running/key in pocket, while looking up under dash, at top end of brake pedal & watching brake switch function.
If the brake light switch "directly operates the stop lamps" it would appear to be in addition to the obvious relay closing for "shift interlock, speed control, etc" w/key off.
However, I can assure readers that on my '98 F150 the brake light "switch itself" is silent, AND each time my brake pedal gets pushed down slightly I hear the unmistakable click of a relay closing off to the passenger side behind the dash.
Note that the click is a faint sound heard w/motor not running/key in pocket, while looking up under dash, at top end of brake pedal & watching brake switch function.
If the brake light switch "directly operates the stop lamps" it would appear to be in addition to the obvious relay closing for "shift interlock, speed control, etc" w/key off.
Lead Driver
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A look at a service disc shows pins 1,2, and 3 are the cruise control knock-off.
They remove a 'normal ground' and apply battery to the servo.
The pressure switch does the oppisite, cuts power to the servo as a backup shut down to C. C.
Pins 4,5 apply battery directly to the stop lamps and to the trailer relay for remote stop lights through the towing connector.
Trailer relay has it's own fused feed to pass power back to the trailer connector.
There are other places in the circuit that also get a feed are the shift interlock relay and some other functions for trasmission control through PCM action etc.
About the only relay you might hear is the trailer relay operating.
Basicly the brake switch supplies power directly to the stop lamps.
They remove a 'normal ground' and apply battery to the servo.
The pressure switch does the oppisite, cuts power to the servo as a backup shut down to C. C.
Pins 4,5 apply battery directly to the stop lamps and to the trailer relay for remote stop lights through the towing connector.
Trailer relay has it's own fused feed to pass power back to the trailer connector.
There are other places in the circuit that also get a feed are the shift interlock relay and some other functions for trasmission control through PCM action etc.
About the only relay you might hear is the trailer relay operating.
Basicly the brake switch supplies power directly to the stop lamps.
Hotshot
Joined: Jan 2004
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From: St Louis
You might be hearing a relay from one of the module that uses the brake pedal switch as its input, but your 98 F150 didn't come from the factory with a relay that operates the truck's brake lights when the pedal is pressed. There are relays under the hood for the trailer brake lights, if so equipped, that do energize off the brake lamp switch. If your 98 is equipped with RABS, that module is under the right side of the dash. Perhaps it has a relay than can be heard.
The 98 F150 uses a simple two-terminal, normally open SPST switch.
The 98 F150 uses a simple two-terminal, normally open SPST switch.
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My hearing is plainly acute enough to tell if the relay that clicks when brake pedal is depressed emanates from "under the hood" or "under the right side of the dash".
My "98 is equipped with RABS" however I'd assumed that antilock brake system wouldn't be energized w/the key off, whereas the brake light circuit is always energized.
So why are fordonly4me's "Tail lights slow to come on" & "brake lights wouldn't come on unless I pressed the peddle down hard"?
You might be hearing a relay from one of the module that uses the brake pedal switch as its input, but your 98 F150 didn't come from the factory with a relay that operates the truck's brake lights when the pedal is pressed. There are relays under the hood for the trailer brake lights, if so equipped, that do energize off the brake lamp switch. If your 98 is equipped with RABS, that module is under the right side of the dash. Perhaps it has a relay than can be heard.
So why are fordonly4me's "Tail lights slow to come on" & "brake lights wouldn't come on unless I pressed the peddle down hard"?
Hotshot
Joined: Jan 2004
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From: St Louis
Already explained it above.....
Go read this thread: https://www.ford-trucks.com/forums/1...he-brakes.html The 97 Expy and 98 F150 use the same circuitry.
Go read this thread: https://www.ford-trucks.com/forums/1...he-brakes.html The 97 Expy and 98 F150 use the same circuitry.
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