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Re: Connections on starter motor solenoid

To: "Pim Alferink" <fam.alferink@zonnet.nl>, "6pack"
Subject: Re: Connections on starter motor solenoid
From: "Nelson A. Riedel" <nriedel@nextek.net>
Date: Sun, 18 Mar 2001 07:38:47 -0500
Dear listers,
Is there anyone who can shine some light on the electrical connections on
the starter motor solenoid?
I am specifically interested in the function of the smallest wire attached
to the solenoid spade labeled "IGN".
I have been using the car for more then a year without that this wire was
attached (the connector broke from the cable a long time ago). Never any
problem.
Testing the voltage on the wire, I found that it is about 5V when the key is
in the normal position for a running engine.
Questions: what is the function of this connection and why is it 5V?

(P.S. See, LUCAS not ain't that bad. Even without connections it works
wonders.)

Pim Alferink
Pimento CF1362U (now O), with recent Koni rear shocks.
--------------
Pim,

 The '73 and later TR6s use a 6 volt coil.  The wire between the ignition
switch and the coil is a ballast resistor that drops the normal 12 volts at
the ignitiion switch to 6 volts at the coil.

The wire you mentioned (it should be white with a yellow stripe) runs from
the starter selinoid to the coil.  When not starting, it should read the
normal coil voltage (the 5 volts you measured --- should have been 6 or 7
volts, but close enough).

When the solenoid is engaged, full battery voltage is placed on this wire by
the solenoid,  and since it is connected to the coil, full battery voltage
is placed on the coil.  This bypasses the ballast resister.   The purpose of
this is to offset the effect of the lowered battery voltage during starting
and provide a hotter spark during starting.

When the wire is not connected, operation is the same as pre '73 TR6s  ----
a poorer spark during starting.  If you have a good battery at it isn't very
cold you'll probably not notice the difference.

The 6 volt coil and ballast wire require special consideration when
replacing the coil or installing an electronic ignition. If you want to
learn more about the TR6 electrical system you might consider purchasing Dan
Master's book described at the following website:

 http://members.aol.com/danmas6/

Nelson Riedel
Granville, OH
76 TR6 (at paint shop)
68 TR250 (next project - new paint)
70 TR6 (all the parts in a pile ready to assemble)

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