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Matt
Matt, Engineer
Category: Nissan
Satisfied Customers: 20605
Experience:  BEng hons Mech engineering, worked in auto industry for 22 years on engine, transmission and suspension design
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2002 Xterra. My wife was driving alone, and when she pressed

Customer Question

2002 Xterra. My wife was driving alone, and when she pressed the brake pedal, the "set" light illuminated on the panel. Removing her foot from the brake made "set" extinguish. This repeated for the whole trip in-town for the*****(no cruise control was used). Once she parked and shut down the engine, the brake lights would not go off. I pulled the 20AMP fuse so as to not flatten the battery. I'm thinking it is the brake-lamp switch on the pedal-arm.... if that's where it is.... it was getting dark and it is difficult for me to get my head under the panel. We've owned the car since new and it has ~150,000 miles on it.
JA: Have you checked the fuse? What size is your engine?
Customer: The fuse is fine. Please read my paragraph. It has the V6 and is rear-wheel drive.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes, I will repair myself. This just happened, so I have tried nothing, as it was getting very dark outside.
JA: Anything else you think the mechanic should know?
Customer: I find it strange that the brake-light circuit makes the "set" lamp illuminate.... or are these two separate issues. Neither ever happened before and both happened simultaneously for the first time ever, tonight.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Nissan Mechanic about your situation and then connect you two.
Submitted: 5 months ago.
Category: Nissan
Expert:  Matt replied 5 months ago.

Hello

1st thing to check is the condition of the brake lights

as the resistance of the bulb circuit is used to help control the system

the bulb should be a 3157 dual filament bulb

if one has blown or has a corroded socket then this can create the issue you describe

and yes I'd also check the condition of the brake pedal switch thats located at the top of the pedal in the drivers footwell

the switch operation can be tested with a meter to ensure it has no high resistance and is definitely switching off

Customer: replied 5 months ago.
Problem is now identified: The arm of the brake pedal has two holes aligned with the two switches (Stop Light and Disengage Cruise Control). Into these holes are inserted some nylon buttons, I presume to lower the friction between the switch-plungers and their contact points on the arm. With no foot on the pedal, the Brake-Light button depresses the plunger holding the light circuit open (brake lights out). When the driver's foot depresses the pedal, the button is moved away from contacting the Normally Closed (NC) switch plunger and the Brake Lights are energized.
This button has disintegrated and fallen out.... so the plunger passes through the vacant hole where the button used to be, ergo the Brake-Lights are always on as there is NOTHING to depress the plunger. This is an incredibly stupid design, as the absence of a two-cent giblet of nylon renders the Brake Light circuit constantly on whether the engine is running or not. A smarter design would have a nylon cap on the end of the plunger as a part of the switch manufacture.... new switch / new friction contact surface.
As is, these silly giblets of nylon are in actuality made of un-obtain-ium.... as no one, anywhere has them in inventory. Wouldn't it have been smart to specify that the aftermarket box up the new switches with replacement buttons?
(Same vehicle) This rates right up there with the engineer-idiot who made the detachable disk brake rotors bolt-up to the inside face of the hub, such that the entire hub has to be dismounted from the spindle to change the rotor..... just like the days of old when the rotor and hub were a single, integral casting. So... why have two parts to the hub/rotor if you have to dismount the bearing hub anyway?! Have Nissan's engineers ever even held a damned wrench? I think not.

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