2G Please Help!!! Brake lights don't come on when I press pedal...

[99_GSX_66]

So I've been doing some searching the last few days on the forums for a solution to my problem. So the other day my brake lights decided to quit working...running lights, dash lights, hazards, turn signals all work. Wiring for the aftermarket tails are good and I tested the brake light switch and it's working correctly.

Here's were it gets weird...when I bought the car the lights worked and it didn't have a 15a fuse in the Stop Light port of the fuse box (under hood). When I put a fuse in it the brake lights come on and stay on, but when I depress the brake pedal the lights go off. WTFF??? I can't seem to find anyone else having this exact issue and I'm now steering more towards a short somewhere but the fuse missing doesn't explain why they would just stop all the sudden.

I'm stumped?? any ideas DSM guru's??

 

[luv2rallye]

The factory brake light circuit goes through the "turn signal and hazard flasher unit" so they can also be controlled by the hazard and turn signal switches. Just a guess but almost sounds like maybe someone re-wired your brake/tail lights bypassing that unit (since they worked w/o the fuse). So replacing the fuse is incompatible with their wiring. Are your taillights stock?

 

[miliman13]

Here is what i know

The brakes, works like this= You press the pedal and thus pull the pedal assembly away from the switch. This causes continuity / continuation in the circuit, which feeds power to the rear brake lights.

It's a dead man's switch, same thing used by enemy suicide bombers in iraq.

Clutch switch is opposite it only closes the circuit when the switch is depressed I.E the pedal is pressed down , closing the circuit; thus allowing starter to engage.

Sometimes the little plastic pushers/stoppers get worn out or fall out which conflicts the normal operation of the circuits.

Rally check my work incase i'm off.*


* On that gin currently

 

[luv2rallye]

Ok since you've asked me to check your work.....

Well you've got the brake switch correct although the power doesn't go directly to the brake lights (except on the high mounted stop light it does). Because the same brake lights are also used for turn signals and hazards, that switch feeds the Turn Signal And Hazard Flasher Unit which controls all 3 functions (with internal relays and circuitry) and the brake lights are fed from it.

The clutch circuit is a little bazarre and you may have to read this a few times. Pay attention because there will be a test question after .
On the M/T (A/T is opposite) the starter relay normally stays closed (has continuity to starter). So when key is turned to Start, the relay doesn't even activate since it is already closed. With the clutch pedal up, the clutch switch is closed which puts a ground on the starter relay coil which activates it (when other side of coil is connected to ignition start switch position to provide +12v). This opens the starter relay (disconnects the starter circuit) so the starter won't operate. So activating the starter relay actually opens the circuit to the starter. When the clutch is pressed down, the clutch switch opens up so the relay never gets it's ground so it can't activate (can't disable the starter). Get it?
So why did they make it so complicated? Because 1) you will almost never wear out the starter relay since it never activates to engage the starter, and 2) it makes it very easy to add a theft alarm starter relay that is just in parallel to the clutch switch.

And now the test question: When does the starter relay activate and for what purpose?

(BTW I end up explaining this about every other month to people who PM me when they can't get their starter to operate. Sometimes I tell them to just replace the starter relay with a jumper if you don't need the factory theft alarm to disable the starter. Especially when they have inherited a wiring nightmare.)

 

[99_GSX_66]

The factory brake light circuit goes through the "turn signal and hazard flasher unit" so they can also be controlled by the hazard and turn signal switches. Just a guess but almost sounds like maybe someone re-wired your brake/tail lights bypassing that unit (since they worked w/o the fuse). So replacing the fuse is incompatible with their wiring. Are your taillights stock?

No they are the altezza style tails lights, would the hazards and turn signals still work if that unit was bypassed??

And on a side note, there is a "dinging noise" that is supposed to come on when you leave the keys in the ignition or leave the lights on...right? My car doesn't do that!

 

[spyderdrifter]

Someone could have done the mod to eliminate the key reminder. Maybe they messed up the wiring and as a result, messed up the brake light circuit.

http://www.dsmtuners.com/search/9451368/?q=key+reminder&o=date&c[title_only]=1

 

[luv2rallye]

No they are the altezza style tails lights, would the hazards and turn signals still work if that unit was bypassed??

No, unless they somehow rewired in their own unit.

 

[99_GSX_66]

Not sure what I did but they are working again and I now have a fuse in the stop lamp slot and they don't stay on....pretty sure they will go out again because I didn't fix anything.

 

[EVLGSX]

I am having a similar problem with this GST I just slapped together- started getting excited when I found this thread

But this thread has the lamest ending ever!!! Seriously?

 

[EVLGSX]

I picked this 97 GST up as an auto car that was part way through a manual swap.

The brake lights will not shut off. Its for sure the brake light circuit providing power, as the lights do go off when I pull the 15amp brake light fuse in the engine bay fuse box. The switch at the pedal has been swapped for brand new, and the little blue plastic nub on the pedal is not the issue. I wish it was........

Any ideas?

-again- not the switch or the blue plastic that presses the switch. brake lights stay on (including the back window 3rd light) with the 4 pin pedal switch unplugged..

 

[FIBA M - EC17PSE]

I picked this 97 GST up as an auto car that was part way through a manual swap.

The brake lights will not shut off. Its for sure the brake light circuit providing power, as the lights do go off when I pull the 15amp brake light fuse in the engine bay fuse box. The switch at the pedal has been swapped for brand new, and the little blue plastic nub on the pedal is not the issue. I wish it was........

Any ideas?

-again- not the switch or the blue plastic that presses the switch. brake lights stay on (including the back window 3rd light) with the 4 pin pedal switch unplugged..

Some cars had 2 wires to the brake switch and some had 4! 2 go towards the cruise control unit so maybe its part of that and it things its activated? I can onky guess that the switches might be different and need to see to signals but then again im an auto with 4 wires and i disconnected my cruise control years ago and its just fine,

Maybe get a pic of your switch and when im back with my one i will see if its the same. If you got one of the manual i can check against that.

In the manual it shows it splits off so check the cruise system. I never thought it was part of the system myself either before looking