96 bmw 318iS no brake lights

stuck on before and after, very good evidence, rarely told.
ever see it work right before or buy car broken like this???????
history matters huge as do wiring hacks by others.(trailer hitch)
EVEN SIMPLE THINGS ARE CALIBRATED
THE SERVICE MANUAL COVERS THEM ALL
do not break the brakes.
lots of causes (any real shop can fix it !)
you posted to the blind folks. cant see under that dash.
causes;

1. wrong switch
2. installed wrong,
3. MC installed wrong or is wrong master cylinder, put there.
4. pedal springs missing or bad. or pedal parts missing or broken .

now lets read your manual for switch swaps
what does it say.


the big paste. steps out and back in both


Do not pull on the connector or on the harness with excessive force to disengage the switch wiring. Connector and/or wiring harness damage will result.

1. Detach the wiring harness connector from the BOO switch by using a small pick or prytool to lift the connector retaining tab up, then pulling the connector from the switch.

Since the side plate of the BOO switch nearest the brake pedal is slotted, it is not necessary to remove the brake master cylinder pushrod and one spacer from the brake pedal pin.

1. Disengage the hairpin retainer, then slide the BOO switch, pushrod, nylon washers and bushing away from the brake pedal. Detach the BOO switch from the bracket by sliding it up or down.

To install:
WARNING
Only use hairpin retainers specifically designed for the BOO switch.

1. Position the BOO switch so that the U-shaped side is nearest the brake pedal and directly over the pin. Slide the switch down until it has trapped the master cylinder pushrod and blade bushing between its side plates.
2. Press the BOO switch and pushrod firmly toward the brake pedal arm, then assemble the outside white nylon washer to the pin.
3. Install the hairpin retainer to securely hold the entire assembly.

The BOO switch wiring harness must have sufficient slack to allow brake pedal movement. After attaching the connector to the switch, ensure that there is enough play in the harness.

1. Insert the wiring harness connector into the BOO switch connector until the retaining tab is fully engaged.
2. Have an assistant sit in the vehicle and apply the brake pedal while you watch the brake lamps for proper function. The brake lights should illuminate even with the ignition switch in the OFF position. If they do not illuminate when the pedal is depressed, there is a problem within the switch or circuit.

as you can see it is not just snap on /off deal.

cars this old I have seen and repaired
bad pedal cracks, parts crack and fail and I weld them back with TIG.
things to see, there behind the firewall MC spot? (place)up top far.
the brake pedal top push rod pushes the MC rear piston!
and must have some play there, pedal UP. if not car is a super danger to drive like that. the MC must fully retract or MC fails.
why it fails can only be known eyes on hands on by a real tech.
the brake lamp failing can just be a side show, just warning gee
somethings is very wrong hear or the switch bad, or not installed correctly
see?
MC means brake master cylinder. rear. and most not leak either
best is let a real brake man (person) inspect it all. and be safe.
also some brands brake switch new in a box
open box has instructions, that many include, how to calibrate it.

Hello,

REMOVAL

1. Disconnect the wire harness at the connector from the stoplight switch.

NOTE: Locking tab on connector must be lifted before connector can be removed.

1. Remove the hairpin retainer and slide the stoplight switch, the push rod and the nylon washers and bushing away from the brake pedal. Remove the stoplight switch by sliding the stoplight switch up/down as required to remove.

NOTE: Since the stoplight switch side plate nearest the brake pedal is slotted, it is not necessary to remove the brake master cylinder push rod and one spacer washer from the brake pedal pin.

INSTALLATION

1. Position stoplight switch so that the U-shaped side is nearest the brake pedal and directly over or under the pin. Then slide stoplight switch down or up trapping the master cylinder push rod and black bushing between the stoplight switch side plates. Push stoplight switch and push rod assembly firmly toward brake pedal arm. Assemble outside white plastic washer to pin and install hairpin retainer to trap whole assembly.

CAUTION: Do not substitute other types of pin retainers. Replace only with a production hairpin retainer. Component damage may occur.

1. Assemble the wire harness connector to the stoplight switch.

NOTE: Stoplight switch wire harness must have sufficient length to travel with stoplight switch during full stroke of brake pedal. If wire length is insufficient, reroute harness or service as required.

1. Check stoplight switch for proper operation.

Hi,here's a link showing a pic of your brake light switch,it is attached to your brake pedal,easy to remove,just disconnect electrical connector and clip holding it on. Stoplight Switch at AutoZone com Best Stoplight Switch Parts for Cars...

• Push the driver's seat as far back as possible, allowing you to lay on the floor on the driver's side.
  
• 2 Shine a flashlight at the top of the brake pedal stalk and find the stoplight switch. It will be a plastic cube either connected to the brake stalk or directly opposite the brake stalk, depending on the vehicle.
  
• 3 Depress the brake pedal and feel where the brake light switch contacts the stopping plate, a metal plate in direct line with the stoplight switch.
  
• 4 Feel for an open hole where the stoplight's plunger-style button presses. If a hole is present, you simply need to replace the rubber stopper.
  
• 5 Press and release the plunger-style button on the brake light switch and ask an assistant if the brake lights are turning off and on. If not, the switch is bad and must be replaced.
  

Stoplight Switch Stopper Replacement

• 1 Clean out any remaining debris left behind by the old stopper from the hole that the stopper goes into.
  
• 2 Press the new stopper into the hole on the metal plate until it snaps into place.
  
• 3 Shine the flashlight on the stopper and check that it sits flush against the metal plate.
  
• 4 Press and release the brake pedal and ask your assistant if the brake lights are turning off and on.
  
• 5 Replace the stoplight switch if the lights continue to stay on.
  

Stoplight Switch Replacement

• 1 Loosen and remove the bolts holding the stoplight switch in place. It could be between one and four bolts depending on the vehicle.
  
• 2 Pull the stoplight switch from its mount. Disconnect the wiring harness from the stoplight switch by pressing or pulling the locking tab and puling the harness away from the switch.
  
• 3 Plug the wiring harness into the new switch until the locking tab clicks into place.
  
• 4 Place the new switch on the mount the old switch was removed from and tighten the bolts with a ratchet and socket.
  
• 5 Press and release the brake pedal several times and have your assistant check for proper operation.
  

Your stop light switch has failed. This is the switch operated every time you operate the brake
pedal. This switch fails in one of two ways - always open (brakes lights don't work), or always
closed (brake lights won't turn off).

To replace a stoplight switch, first determine what type of switch you have.

If you have an electrical switch mounted to the brake pedal in the passenger compartment:

* Unplug the wire connector at the back of the switch.
* Unscrew the switch.
* Replace with a new switch. Adjust the adjustment nut as needed.
* Plug the wires back in.

If you have a hydraulic pressure switch that is mounted in the brake master cylinder:

* Mark and disconnect the wires.
* Unscrew the switch.
* Screw the replacement switch in.
* Reconnect the wires.


2002 Ford Expedition stoplight switches - photo from www.autozone.com

When a vehicle's brake lights all go out at the same time, the culprit is usually the
"stoplight Switch" which is operated by depressing the brake pedal.

To replace a stoplight switch, first determine what type of switch you have.
If you have an electrical switch mounted to the brake pedal in the passenger compartment:

• Unscrew the switch.
• Unplug the wires.
• Replace with a new switch. Adjust as needed.
• Plug the wires back in.

If you have a hydraulic pressure switch that is mounted in the brake master cylinder:

• Mark and disconnect the wires.
• Unscrew the switch.
• Screw the replacement switch in.
• Reconnect the wires

Here's a picture of the "Stoplight Switch", aka Brake Light Switch - 1995 GMC K1500 Sierra



Brake lights (stoplights) are activated by a mechanical switch on the brake pedal.
To test a suspected bad stoplight switch, bypass it with a jumper wire. The stoplights should light when the wires are connected. Use the test light to see if there is power at one of the lights.

• If the lights come on when the wires are connected but not when the brakes are applied, replace the switch.
• If the stoplights operate without the key on, remove the stoplight fuse before removing the switch.
• If the new switch is adjustable, adjust it so that it is open when the pedal is released.lights should come on about 1/4" after the pedal is applied.

1. Disconnect the negative battery cable.
2. Unplug the wire harness at the connector from the switch mounted at th brake pedal. The locking tab must be lifted before the connector can be removed.
3. Remove the hairpin retainer, slide the stoplight switch, the pushrod and the nylon washers and bushings away from the pedal and remove the switch. NOTE: Since the switch side-plate nearest the brake pedal is slotted, it is not necessary to remove the brake master cylinder pushrod and washer from the brake pedal pin. To install:
   
4. Position the switch so the U-shaped side is nearest the pedal and directly over/under the pin. Slide the switch down or up, trapping the master cylinder pushrod and black bushing between the switch side plates. Push the switch and pushrod assembly firmly toward the brake pedal arm.
5. Assemble the outside white plastic washer to the pin and install the hairpin retainer to trap the whole assembly.
6. Assemble the wire harness connector to the switch. Check the switch for proper operation. Connect the negative battery cable. NOTE: The stoplight switch wire harness must be long enough to travel with the switch during full-pedal stroke. If the wire length is insufficient, reroute the harness or service, as required.
   

Fig. 1: Brake pedal assembly

fuse #7 - 15 amp , Fuse #21 - 10 amp.

Maybe you blew solid state module. There is a manual bypass.

Shift Interlock System A shift interlock mechanism prevents shifting the transaxle out of the PARK position unless the brake pedal (2455) is applied. The shift lock actuator is energized when the ignition switch is turned to the RUN position.

• This locks the shifter in the PARK position.
• When the brake pedal is applied and the stoplight switch (13480) is activated, the shift lock actuator is deactivated and the shifter can be moved out of the PARK position.

-----------------------------------------------------

• Shift Interlock System Does Not Release or Lock Properly

• Fuse.
• Circuit.
• Shift lock actuator.
• Gearshift lever adjustment.
• Stoplight switch.

----------------------------------------------------------

If the brake lights are coming on,then the brake light switch on the brake pedal is the problem,just replace it,and that will solve the problem.

Hi there,

Well you can please follow the below steps -
A. Disconnect the negative battery cable.
B. Detach the connector from the stoplight switch.
C. Remove the hairpin retainer and the white nylon washer.
D. Slide the switch and pushrod away from the pedal.
E. Remove the stoplight switch by sliding it down.
F. The installation is the reverse of removal.
Please post comments for more help or information........

Good Luck!!

Thanks