Stop Light switch & torsion level

Discussions related to braking systems.
dad5355packard
Posts: 13
Joined: Fri Feb 24, 2012 7:30 pm

Stop Light switch & torsion level

Post by dad5355packard » Tue Jun 12, 2012 5:31 pm

I have a 1955 400. The torsion level works sometime, when I get the system to work, the first time I step on the brake the system stops working. The brake lights do operate. There is no power to the control switch under the dash. Is this a stop light switch problem, I am thinking it is but do not know enough about the system. Any help or suggestions appreciated. How do I test this?
Lou Manus

Dave Czirr
Moderator
Posts: 5075
Joined: Tue Jun 16, 2009 5:30 am
Location: New Jersey

Re: Stop Light switch & torsion level

Post by Dave Czirr » Tue Jun 12, 2012 6:29 pm

I'm not sure I understand the full extent of whatever problem you may have, but the TL system is deliberately inactivated when applying the brakes. This is so the system doesn't try to compensate for the "nose dive" that accompanies application of the brakes. This is the reason you have a unique brake light switch with 3 terminals; one circuit is closed (brake lights) when you apply the brakes, the other circuit is opened (TL system),

If there was more to the question, let us know. The TL system is covered quite well in the shop manual and I suggest you start with a good review of it.

dad5355packard
Posts: 13
Joined: Fri Feb 24, 2012 7:30 pm

Re: Stop Light switch & torsion level

Post by dad5355packard » Wed Jun 13, 2012 8:56 am

I wasn't very clear in my original post. I understand the deactivation when applying the brakes. What happens is that when the brakes are released the system continues to be deactivated. The system had been working properly and when I took a trip, it worked for about 1 day then started acting up, first letting the rear end go low, then overnight parked would regain its height. Then the next day it would not work but while I was driving it started working putting the car in to a tail high position that locked in. The third day it returned to normal position and locked in there. Since then it has intermittently worked but now it is locked level( which is OK) but does not operate. After the last time applying the brake it completely deactivated the system.

Dave Czirr
Moderator
Posts: 5075
Joined: Tue Jun 16, 2009 5:30 am
Location: New Jersey

Re: Stop Light switch & torsion level

Post by Dave Czirr » Wed Jun 13, 2012 10:42 am

Thanks for the more comprehensive explanation. My own T/L system has always worked flawlessly so I'm not the best at a diagnosis, I'll ask a friend Randy Berger to look at this post and see if he can help. I guess it can be a result of an intermittendly failing brake light switch, or even a problem with the "brain" and the delay circuit. Fortunately there are easy solutions to both, you can purchase a little kit to replace the brake light switch with a normal two-pole switch and relay, and there are solid-state conversions of the brain available from the same source (P.N.R.) if you have a decent core. If you're not familiar with the source, I can scan their ad for you, just let me know.

Dave
Attachments
55-56 PI brake light kit.jpg

Randy Berger
Posts: 206
Joined: Tue Jul 07, 2009 8:00 pm

Re: Stop Light switch & torsion level

Post by Randy Berger » Wed Jun 13, 2012 11:17 am

If your vehicle is going up and down and is out-of-level, then I can only assume you have a problem with the "brain" that controls the function.
If you don't have power at one of the terminals of the dash switch with the green wires, then it sounds like a bad brake-light switch.
The terminals of the green wire are brass and so are the switch terminals. Try removing the switch and clean those terminals and the connectors at the ends of the green wires - with the battery disconnected ;)
Cleaning the terminals at the three prong brake switch is also a good idea.
If this doesn't work, you can send your unit to P.N.R. for the solid-state version and also replace the brake-light switch.

Dave Czirr
Moderator
Posts: 5075
Joined: Tue Jun 16, 2009 5:30 am
Location: New Jersey

Re: Stop Light switch & torsion level

Post by Dave Czirr » Thu Jun 14, 2012 5:09 am

Information on P.N.R.
Attachments
P.N.R.jpg

dad5355packard
Posts: 13
Joined: Fri Feb 24, 2012 7:30 pm

Re: Stop Light switch & torsion level

Post by dad5355packard » Fri Jun 15, 2012 7:49 am

Thanks for all the good information. It turned out to be the stoplight switch. I replaced both the underdash switch and the stoplight switch and the system seems to be working normally. I found that after stepping on the brake, it takes about 10 seconds after releasing the brake for the system to operate.

I will followup on the other suggestions as they will make the car more reliable.

Lou Manus

Dave Czirr
Moderator
Posts: 5075
Joined: Tue Jun 16, 2009 5:30 am
Location: New Jersey

Re: Stop Light switch & torsion level

Post by Dave Czirr » Fri Jun 15, 2012 7:58 am

Thanks for the update, always good to hear a story with a happy ending. The time delay on mine is closer to 7 seconds but I think varying a few seconds one way or the other is pretty typical.

If you used an original OEM brake switch, I'd be curious where you got it, they gotten to be pretty rare items these days, and generally don't last long with silicone brake fluid.

dad5355packard
Posts: 13
Joined: Fri Feb 24, 2012 7:30 pm

Re: Stop Light switch & torsion level

Post by dad5355packard » Fri Jun 15, 2012 10:09 am

I purchased and aftermarket switch from Max Merritt parts. I recently had the brakes rebuilt, everything new including the lines and the rebuilder put DOT 3 in the system. I have one question, can the system be left turned on all the time or do I need to turn it off when it will sit for a while?

Lou Manus

Dave Czirr
Moderator
Posts: 5075
Joined: Tue Jun 16, 2009 5:30 am
Location: New Jersey

Re: Stop Light switch & torsion level

Post by Dave Czirr » Fri Jun 15, 2012 10:22 am

Lou, I suspect there's quite a split on that. I tend to leave mine off most of the time except when putting a heavy load in the trunk or extra passengers in the back seat - I'll then turn it on to level and when that's achieved, I turn it off again. Others I know leave it on all the time and either way seems OK. But one thing we all should do is have a battery kill switch and turn off the battery during periods of inactivity.

Post Reply