Another Brake Light Question

skeeter · #1 (**permalink**) 02-23-2002, 02:58 PM

Any Ideas?
My brake lights are not working. Signal and running lights work. I have power to the green wire going into the brake light switch at the master cylinder. Shorting both wires and pushing the brakes does nothing. How do you determine if it is the switch or a wiring problem?

Thanks,
David

Whaler · #2 (**permalink**) 02-23-2002, 05:30 PM

Jumper the switch. Connect a jumper between the two spades and that should give you continuity to the lights with your hot lead.
You will be effectively closing the switch as if you had applied brake pedal pressure to the hydraulics..If you have lights then, your wiring is fine, but the switch is toast.
No need to push on the brakes with this test.
Another check is to take the leads off the switch connect a meter to the spades using ohms set on resistance..pump the brake now and see if the switch is closing ( low to 0 ohms ) and reading Megaohms when no brake pumped

Tim

skeeter · #3 (**permalink**) 02-23-2002, 05:53 PM

Well, it is definetly the switch. Thanks for the help Whaler! Funny that both switches would be bad. Now to find that part...

David

John 550 · #4 (**permalink**) 02-23-2002, 08:10 PM

While one the topic , My break lights only come on if I push extreamly hard on the pedal , any ideas ?

Whaler · #5 (**permalink**) 02-24-2002, 10:29 AM

any Napa can get you the part you need its an echlin switch.
Echlin part # SL147

See the thread we had up just before yours for those details

brake switch thread

Tim

Whaler · #6 (**permalink**) 02-24-2002, 10:38 AM

John 550
The only idea I have is that there may be some resistance in the contacts or that the actual triggering setpoint is getting higher with age/use.

I took a fresh new switch in to work and tested it out..it closed at 70 psi
The napa catalogue said it had an actuation setpoint of 60-120 psi....
Mine was at the low end obviously....could this change and require more brake force to close?? who knows?
They are cheap to replace and easy to test... with the switch out of the car, rig up a 0-100 or 0-200 # gauge and a pressure source and the switch all on a 1/8" pipe tee, use a meter on it as well.

Pressurize it slowly until you see it close on the meter ( resistance) see where it closes on the gauge
...if it is real high, replace it..12 bucks US or so....

Also reset is another consideration..where it goes back to normally closed state. after being triggered onset...you want no real differential between these two pressure other wise you will have a light that stays on after brakes have been let off.

Is your switch new or has it been in service long? Mechanical switches are only good for so many cycles in life. usually the high thousands

See the thread that I referred Dave to for part# napa

Tim

skeeter · #7 (**permalink**) 02-24-2002, 11:13 AM

Whaler,
Apparently the 427 uses a different switch than the FIA. Mine is a 3 spade that is considerably larger than the one that matches the numbers you gave which is a 2 spade. BOB P. do you have numbers or cross reference for the FIA brake switch. Mine is an early FIA so it may be different than a later model.

David

Whaler · #8 (**permalink**) 02-24-2002, 11:25 AM

This info Bob supplied on the thread I referred you to

" The switches are VW Rabbit/Golf/Late Beetle. Part number 112 945 515G. You can probably find one at your local jobber (although I can send you a couple if you can wait). "

If yours is a three spade that simply means you have both the N.O and N.C. contacts as well as common....do you actually use all three spades?? Why not see what Napa has that is 3 spade configuration then..otherwise Bob has given you a number in the ERA applications

Tim

skeeter · #9 (**permalink**) 02-24-2002, 12:06 PM

Tim,
Unfortunatley the NAPA store is closed today, I was trying to deal with the other stores here, but they have to have the exact part number, or cross reference to find anything. I don't really need the 3 spade, but the 2 spade they did have would not fit my plug. I will just wait and hit the NAPA store tomorrow. Thanks for the help.

David

Bob Putnam · #10 (**permalink**) 02-24-2002, 04:02 PM

We use the same switch on the FIA - but only use two of the three terminals. The thread pitch is 1/8NPT so most equivalent two-bladed switches will be compatible.

427Aggie · #11 (**permalink**) 02-27-2002, 02:31 PM

I actually have the same problem as John 550...I can only get my brake lights to come on when I press really really hard.

Any idea's Bob?

matt

Bob Putnam · #12 (**permalink**) 02-27-2002, 04:16 PM

Matt,

Same problem - same solution.

Unfortunately, those switches tend to go bad after a while.

427Aggie · #13 (**permalink**) 02-27-2002, 05:39 PM

Thanks Bob and you should see the car with Webbers on it now

Actually I guess I can upload it hehe..

Matt