No Brake Lights - Again!
Thread Starter
Le Mans Master
Joined: Jul 2000
Posts: 6,001
Likes: 112
From: Saginaw Michigan
No Brake Lights - Again!
Last year my brake lights didn't work. Every once in a while, they would work ONCE then nothing! After much searching I found a capacitor wired across the brake light switch. Bubba had wired it sometime before I bought my 1975 Vert 18 years ago. I figured that the capacitor went bad with time. I removed it and my brake lights seemed to work correctly.
Now I seem to have the same problem again. (But there is NO capacitor in the circuit.)
I have turn signals, hazard flashers, and running lights. Just very intermittant brake lights.
I checked the orange wires to the brake light switch - 12 volts. I checked continuity of the switch itself - seems to function correctly. So now I am led to the Saginaw steering column. BTW, a NOS T&T turn signal switch is a VERY difficult part to find.
Any ideas would be appreciated?
Now I seem to have the same problem again. (But there is NO capacitor in the circuit.)
I have turn signals, hazard flashers, and running lights. Just very intermittant brake lights.
I checked the orange wires to the brake light switch - 12 volts. I checked continuity of the switch itself - seems to function correctly. So now I am led to the Saginaw steering column. BTW, a NOS T&T turn signal switch is a VERY difficult part to find.
Any ideas would be appreciated?
Drifting
Joined: Aug 2002
Posts: 1,731
Likes: 22
From: Marietta Ga.
Jim, before going into the column, you might try disconecting the column fed and using a jumper to apply 12 volts to the hot side of the brake switch and then operate it by hand to see if you get the same results(bad switch or beyond not coulmn). Then try applying power to out lead (if lights work, bad switch, if not bad wire to rear). Since turn signals and hazards work fine and use the same blub filaments and grounds, that just leaves switch, and power wireing to be at fault. ( I think,could be way off base, but would try above).
Drifting
Joined: Sep 2000
Posts: 1,983
Likes: 78
From: SoCal.
Originally Posted by Jim Shea
... Bubba had wired it sometime before I bought my 1975 Vert 18 years ago. ...
George
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Jim Shea
I have turn signals, hazard flashers, and running lights. Just very intermittant brake lights.
I checked the orange wires to the brake light switch - 12 volts. I checked continuity of the switch itself - seems to function correctly. So now I am led to the Saginaw steering column. BTW, a NOS T&T turn signal switch is a VERY difficult part to find.
Any ideas would be appreciated?
I checked the orange wires to the brake light switch - 12 volts. I checked continuity of the switch itself - seems to function correctly. So now I am led to the Saginaw steering column. BTW, a NOS T&T turn signal switch is a VERY difficult part to find.
Any ideas would be appreciated?
Thread Starter
Le Mans Master
Joined: Jul 2000
Posts: 6,001
Likes: 112
From: Saginaw Michigan
Looking at the electrical schematic, I should be able to disconnect the body harness from the steering column turn signal switch. Then I should be able to jumper the White wire coming from the brake light switch directly to the Dark Green and the Yellow wires going to the rear lights. If they go on when I depress the brake pedal, the problem should be in the column itself.
BTW, what I called a capacitor that was mounted on the intake manifold was actually the tachometer filter.
The capacitor that was connected across the brake light switch (that I removed last year) was spiced into the wiring with those blue clamshell splicers that you can buy at Radio Shack etc. I have never seen wiring from the factory with those blue splicers. Maybe the dealership may have installed the capacitor, but I doubt that St. Louis did.
I can't trouble shoot any more today - big game between Purdue and mighty Michigan that I need to watch.
BTW, what I called a capacitor that was mounted on the intake manifold was actually the tachometer filter.
The capacitor that was connected across the brake light switch (that I removed last year) was spiced into the wiring with those blue clamshell splicers that you can buy at Radio Shack etc. I have never seen wiring from the factory with those blue splicers. Maybe the dealership may have installed the capacitor, but I doubt that St. Louis did.
I can't trouble shoot any more today - big game between Purdue and mighty Michigan that I need to watch.
Race Director
Joined: Feb 1999
Posts: 19,659
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From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
One thing you might try, disconnect the brake light switch and put a jumper across at this point. If this makes the brake lights come on, you know the switch is intermittent and needs to be replaced. Make sense?
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Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
Jim,
I recently broke one of the little legs on one side of my turn signal switch cancelling cam. You may recall the post over in C2. I very quickly learned how rare that part is. It is unique to 1967 and 1968, coinciding with/sandwiched between the introduction of four-way flashers in 1967 and moving the ignition to the steering column in 1969. Most catalogues don't even show a listing and if they do the word "discontinued" is alongside.
With the help of the NCRS people I was able to locate one at the company shown below. I recognize that this is not going NOS but I can assure you the quality is top-notch and fitment was perfect. Just a tip in case you need that switch.
http://shee-mar.com/
I recently broke one of the little legs on one side of my turn signal switch cancelling cam. You may recall the post over in C2. I very quickly learned how rare that part is. It is unique to 1967 and 1968, coinciding with/sandwiched between the introduction of four-way flashers in 1967 and moving the ignition to the steering column in 1969. Most catalogues don't even show a listing and if they do the word "discontinued" is alongside.
With the help of the NCRS people I was able to locate one at the company shown below. I recognize that this is not going NOS but I can assure you the quality is top-notch and fitment was perfect. Just a tip in case you need that switch.
http://shee-mar.com/
Last edited by Paul L; Oct 23, 2004 at 01:57 PM.
Thread Starter
Le Mans Master
Joined: Jul 2000
Posts: 6,001
Likes: 112
From: Saginaw Michigan
My problem continued. Every once in a while the brake lights would go on when I depressed the brake pedal. They might even work a few times and then they stopped going on. Turn and hazards continued to work all of the time when actuated.
I connected a new turn signal switch to the column and the problem remained.
I removed brake light switch and checked for continuity with my multimeter. It showed continuity every time I released the plunger. I depressed the plunger slowly; I depressed it partially and back; I depressed it quickly; I released it slowly; I could not trick it into not working.
75rag4sp suggested to just replace the brake light switch anyway. I purchased a new switch and hooked it onto the underdash harness. The new brake light switch fixed the problem.
Any thoughts as to why the original white switch can be intermittant when hooked in the vehicle circuit, yet check good 100% of the time when checked for continuity?
I connected a new turn signal switch to the column and the problem remained.
I removed brake light switch and checked for continuity with my multimeter. It showed continuity every time I released the plunger. I depressed the plunger slowly; I depressed it partially and back; I depressed it quickly; I released it slowly; I could not trick it into not working.
75rag4sp suggested to just replace the brake light switch anyway. I purchased a new switch and hooked it onto the underdash harness. The new brake light switch fixed the problem.
Any thoughts as to why the original white switch can be intermittant when hooked in the vehicle circuit, yet check good 100% of the time when checked for continuity?
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Jim, if it makes you feel any better, I fought my brake light switch to the exact same conclusion about 2 months ago....
I took the old one apart, the contacts are a mess....
I tried to fix it...same thing.....
think I used an instock NAPA switch for 8 bux.....
sorry I didn't spot post earlier....
GENE
I took the old one apart, the contacts are a mess....
I tried to fix it...same thing.....
think I used an instock NAPA switch for 8 bux.....
sorry I didn't spot post earlier....
GENE
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Surprised Gene didn't answer the last question.
With corroded contacts, a meter will show continuity - since
it uses very little current to check.
However, the brake bulbs are a very low resistance, so lots of current
will flow when connected to them. If the corrosion contributes just a
few Ohms (or tens), it can be enough to limit the current and
effectively shut off the bulbs. If you pulled the lenses, you might have seen a dim glow.
With corroded contacts, a meter will show continuity - since
it uses very little current to check.
However, the brake bulbs are a very low resistance, so lots of current
will flow when connected to them. If the corrosion contributes just a
few Ohms (or tens), it can be enough to limit the current and
effectively shut off the bulbs. If you pulled the lenses, you might have seen a dim glow.
Tech Contributor
Joined: Aug 1999
Posts: 14,373
Likes: 6,372
From: At my Bar drinking and wrenching in Lafayette Colorado
Hi Jim!
Just saw your post and thought I'd check in and say hello!
I had exactly the same issue on my '85 recently. I finally figured it out with the following high-tech troubleshooting process:
Removed the kick panel under the steering column. Whenever the brake lights failed, I give the column/switch area a swift kick. Brake lights would work again. Conclusion: bad switch. Replaced the switch, and all is well. I bench-tested the old switch and could not get it to fail under any conditions, so I re-inrtalled it just to see: no brake lights. New switch is now working great, and I don't have to kick my car before applying the brakes anymore.
Just saw your post and thought I'd check in and say hello!
I had exactly the same issue on my '85 recently. I finally figured it out with the following high-tech troubleshooting process:
Removed the kick panel under the steering column. Whenever the brake lights failed, I give the column/switch area a swift kick. Brake lights would work again. Conclusion: bad switch. Replaced the switch, and all is well. I bench-tested the old switch and could not get it to fail under any conditions, so I re-inrtalled it just to see: no brake lights. New switch is now working great, and I don't have to kick my car before applying the brakes anymore.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Originally Posted by Eddie 70
One thing you might try, disconnect the brake light switch and put a jumper across at this point. If this makes the brake lights come on, you know the switch is intermittent and needs to be replaced. Make sense?
this is the first thing I would do. Twice I found a faulty switch. These are $3.00 switches, nothing special and the local parts store has bins full of them.
Team Owner
Joined: Jun 2001
Posts: 23,367
Likes: 1,061
From: Virginia USA
Originally Posted by Jim Shea
75rag4sp suggested to just replace the brake light switch anyway. I purchased a new switch and hooked it onto the underdash harness. The new brake light switch fixed the problem.
Cool, I though Bubba put the capacitor on mine too a few months back. I removed it and it seemed to help a bit but I still have the same problem you had. My switch doesn’t make a popping noise in my radio but I hardly use the radio
. I also bench checked my switch several time without failure. I can "double press" my pedal when the lights fail to work and the second press will get them to work. I can tell when I am driving because of the fiber optics light monitoring system. 
I am going to get a new switch now. Gene - Do you have a NAPA part number???
Race Director
Joined: Nov 2000
Posts: 16,416
Likes: 1
From: NC,USA
Thankfully on these old cars they dont give you to many electrical possibilities! Its either the switch, the bulb, the wire... or no power/no ground!
A friend of mine works on BMW's... they have headlight modules, electrical computers that control the HID lights! 250 bucks for the panel, 250 bucks for the light that wouldnt come on... the cause non-repairable panel with a burned out diode!
The more I learn about electronics, the more I like the service bulletin that Ferrari sent out (Joke...) back when Jaguar was beating their sales in the 70's... "Replace wiring when smoke has been let out of wire."
A jab at lucas... and their wiring systems!
Some of those things are nuts! Who would think up a hot wired body... where all the wires going to the parts, are the ground! 
A friend of mine works on BMW's... they have headlight modules, electrical computers that control the HID lights! 250 bucks for the panel, 250 bucks for the light that wouldnt come on... the cause non-repairable panel with a burned out diode!
The more I learn about electronics, the more I like the service bulletin that Ferrari sent out (Joke...) back when Jaguar was beating their sales in the 70's... "Replace wiring when smoke has been let out of wire."
A jab at lucas... and their wiring systems!
Some of those things are nuts! Who would think up a hot wired body... where all the wires going to the parts, are the ground!
