Brake and directional light inop

356 Porsche-related discussions and questions.
Post Reply
Message
Author
User avatar
Paul Ahnell
356 Fan
Posts: 504
Joined: Mon Jul 08, 2013 3:18 pm
Tag: What?
Location: Lyme, CT

Brake and directional light inop

#1 Post by Paul Ahnell »

My right rear directional/brake light won't work and I need some guidance.

Background: '60 Normal w/ 6V system. A while back I Installed JF's bright headlights and SMD "bulbs" in place of filament bulbs for brake lights, directional, and parking lights. Have used them for about two years and they are wonderful.

Just bought and installed Zim's electronic flasher so the directionals would flash on the tachometer face. System worked well for a day but then the RR directional/brake light went south.

1. LF, RF, LR directionals work. LR brake light works. All parking lights work.

2. RR directional/brake light doesn't work even though it has a good ground. Tried that SMD in another socket and it works fine.

3. Rear socket voltages left to right are: 5.9; 5.9; 5.9; 2.1 (RR brake/directional). Disconnected wire from socket and got a reading of 2.5 on the wire so I have ~.4 voltage drop in that socket alone.

4. Took out Zim's flasher, reinstalled JF flasher and got the same results. No joy. Reinstalled the Zims.

5. Results shown in #1 above indicates Zim's flasher and the brake light switch function correctly.

6. Evidence points to connections for 54RR shown in Greg Bryan's guide are the problem .

I can't understand why this occurred so suddenly i.e. big voltage drop and light failure. Also, I thought SMDs used just a fraction of the voltage required for a normal filament bulb.

I think I'm going to have to pull the BAL switch and check/clean that to hopefully clear the problem of the big voltage drop (besides that in the socket) and the inop RR brake/directional. Not looking forward to that.

Does anyone have a better take on this and can offer another solution to my problem? I should have paid closer attention in my two required EE courses.
Attachments
Brake-Directionals.pdf
(1.33 MiB) Downloaded 38 times
Brake-Directionals.pdf
(1.33 MiB) Downloaded 33 times
Paul Ahnell
'60 Normal Coupe

User avatar
Jim Nelson
356 Fan
Posts: 2138
Joined: Wed Mar 26, 2008 2:18 pm
Location: SoCal

Re: Brake and directional light inop

#2 Post by Jim Nelson »

I would start with making sure the grounds are clean and well-established.

User avatar
Paul Ahnell
356 Fan
Posts: 504
Joined: Mon Jul 08, 2013 3:18 pm
Tag: What?
Location: Lyme, CT

Re: Brake and directional light inop

#3 Post by Paul Ahnell »

Jim: Thanks for that. The first thing I did was check the SMD "bulb" to confirm it was good then I removed and thoroughly cleaned both ends of the ground wire and mount on the RR housing. Still didn't work. Then I checked voltage to the SMD and found it quite low. Everything else controlled by the flasher, BAL, and brake light switch operates so I suspect it's a connection in the BAL for the RR directional/brake light.
Paul Ahnell
'60 Normal Coupe

Jeffrey Leeds
356 Fan
Posts: 1280
Joined: Sun Apr 20, 2008 4:57 pm
Location: Northeastern MA

Re: Brake and directional light inop

#4 Post by Jeffrey Leeds »

Does this electronic flasher have a separate, independent ground wire?

Jeff
< Jeff >

Registry Member Since 1978
1963 356B T-6 Super 90 Coupe
2009 997.2 Carrera S
2015 958 Cayenne diesel-1 & 2015 958 Cayenne diesel-2

Hugo Karasawa
356 Fan
Posts: 719
Joined: Fri Sep 09, 2016 10:40 pm
Location: Texas

Re: Brake and directional light inop

#5 Post by Hugo Karasawa »

Check the voltage at the connector just before the turn signal switch. Probably your problem lies in the turn signal switch.
Attachments
conn001.jpg
conn001.jpg (33.02 KiB) Viewed 641 times

User avatar
Paul Ahnell
356 Fan
Posts: 504
Joined: Mon Jul 08, 2013 3:18 pm
Tag: What?
Location: Lyme, CT

Re: Brake and directional light inop

#6 Post by Paul Ahnell »

Jeff: Yes, the electronic flasher (Zim's) has an independent ground wire screwed to the forward bulkhead.

Hugo: I agree. I think the major problem is in the BAL switch.

BREAKING NEWS. I was preparing to remove the BAL switch and hose it down with electronic cleaner spray and scrub contacts. Remembering that I had only 2.1v at the RR brake/directional socket I hosed it and the + wire feeding it, cycled the socket center post and voila, I had a bright brake and signal light (new SMD), and 5.7v off the socket. But, only for a minute or so then it started to flutter and dim, and then it came back bright again. Humbling.

So, then I hosed the guts of the BAL switch in situ as best I could with the can's wand and cycled the switch lever a lot. Waiting for it to dry. Not really interested in pulling the steering wheel if I can avoid it. Stay tuned.
Paul Ahnell
'60 Normal Coupe

User avatar
Wes Bender
356 Fan
Posts: 4832
Joined: Wed Aug 27, 2008 10:54 am
Location: Somewhere in the Gadsden Purchase, USA

Re: Brake and directional light inop

#7 Post by Wes Bender »

Paul, if this car was out of service (off the road) for a period of time at some point in its past, it might be a good idea to slowly and carefully go through all of the wiring and connections. Even when you drive these things regularly, the fuses can stand a spin once in a while and some sockets need cleaning a bit.
Some days it's just not worth chewing through the restraints.....

User avatar
Paul Ahnell
356 Fan
Posts: 504
Joined: Mon Jul 08, 2013 3:18 pm
Tag: What?
Location: Lyme, CT

Re: Brake and directional light inop

#8 Post by Paul Ahnell »

Good news. I hosed down the BAL switch in situ earlier with electronic control cleaner und jetz, alles in ordnung. The RR brake light and blinker seem to be working well. Earlier, it would go dim and then brighten. Now, I let it blink for five minutes and it held up well, bright and consistent as designed. I got lucky. That turn signal switch must have been really gummed up.

Wes, good advice which I try to follow, but not regularly enough in this case for the BAL switch. I'll take the time now to check all the sockets and spin fuses as you recommended. Big road trip with "The Boss" planned for next week. She'll be pleased that everything is up to snuff.

Thanks all for hearing me out and providing comments advice.
Paul Ahnell
'60 Normal Coupe

Post Reply