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From: Palmer, Lewis
Sent: Friday, October 27, 1995 9:09AM
To: 'ALAN_COSTICH'
Subject: RE: Turn Signal Control Box
Well, I'll try:
The inside of the control box contains two relays. One for each side of t=
he car. When you turn on the left blinker, the left side relay energizes.=
Likewise for the right.
When the relay energizes, contacts close, thus completing the circuit bet=
ween the flasher and the appropriate leads to the front and rear lights. =
At the same time, the circuit is BROKEN to that side's brake light. This =
allows that side's rear turn signal to operate without interference from =
the brake light, in the event that you apply the brakes at the same time =
the turn signal is operating. (Hopefully, you do brake and signal at turn=
s.)
Typically, the control box is simple to repair. If you look at the cover,=
there will be thin tabs on either end which slip into slots in the base.=
Most often you can simply lift these tabs gently and lift off the cover.=
Make sure you note the orientation as the markings for where everything =
connects are stamped into the cover.
Once the cover is off, you should apply 12 volts across each coil (I can'=
t remember the connector numbers). That should cause the contacts to clos=
e smartly. If this fails, the relay on that side is bad. Very little can =
be done to repair the control box, in that case.=20
If the contacts do close, then the problem is likely to be dirty or pitte=
d contacts. A bit of emery cloth should clean these up easily. If this st=
ill doesn't solve the problem, then it is likely that the contact blades =
have become bent. These are easy to rebend, but be careful. The blade nee=
ds to be bent enough to open/close, but only enough to work AND open the =
corresponding brake light circuit.
If you are at all mechanical, when you open the control box and operate t=
he turn signals, all should be obvious with a little careful study. An oh=
mmeter or test light is also helpful to ensure you are getting the proper=
output to the signals. When energized, the output to the front turn sign=
al should blink on and off 12v. The same for the rear turn signal. The br=
ake circuit should stop receiving 12v - especially when the brake is appl=
ied.
It is fairly simple to make a test jig for these relay boxes. I made one =
out of common parts - total cost was around $20. Just simply follow the w=
iring diagram for the car's brake and turn signal wiring and replicate th=
is on a pegboard. Maybe that's too much for anyone who isn't doing that o=
n a regular basis, but it is easy to isolate whether the control box is o=
perating properly.
Regards,
Lew Palmer
lew.palmer@uci.com
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From: ALAN_COSTICH[SMTP:ALAN_COSTICH@HPATC1.desk.hp.com]
Sent: Friday, October 27, 1995 8:10AM
To: lew.palmer; mgs
Subject: Turn Signal Control Box
Lew,
A short time ago you responded to someone's question
about torn signals on a TD. I offered help with turn
control boxes.
The only one I have come across is in my 57 Magnette.
Help me understand how it works. I do have the shop
manual (although it is not right in fornt of me just
now).
The last time I looked, I think only one side flashed.
This car is not on my priority list, so, I have not
spent a lot of time trouble shooting problems.
Alan
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