Having just spent most of the day pouring over wiring
diagrams, researching old posts, dismantling the wiper motor
and testing circuits I have finally got to the bottom of how
the DL3A wiper Motor works. I thought I would document what
I found in case it is of value to others.
The original S1 wiper motor was the Lucas DL3 (square body)
and as most people know was replaced for the S2 by the Lucas
round body type. The DL3 has six wires plus earth to give
two speed and park. The park position is taken care of by
the park switch on the wiper rack.
In 1967/8 the wiper motor was changed to the Lucas DL3A
which had three wires plus earth and park was taken care of
by an adjustable plate on the motor gearbox. This meant no
switch on the wiper rack and the wiper switch could be a
simpler three contact affair.
My problems arose because the switch on my '63 wiper rack
had, sometime in the past, broken so some bright spark hit
on the idea of replacing the DL3 with a DL3A which meant not
having the unenviable task of removing, repairing and
refitting the rack. When I decided to o/h and refit the
motor the S1 wiring diagram was obviously wrong for what I
was trying to do.
So three wires - many possible permutations into the 6 wire
connector! The DL3A motor works by being permanently live
with the ignition on. The switch controls the earth to
complete the circuit, almost counter intuitive. Also there
are two ‘earths’ (plus the body). For slow speed both the
green/red and the green/brown are switched to earth. For
fast speed only the green/brown is switched to earth - the
green/red is disconnected. Park is of course taken care of
by the paxolin disk and contact on the motor gearbox.
So if you have a broken rack park switch or find a DL3A
motor it will work at two speeds and park when connected to
three of the connections on the loom on an S1 car. To get it
to work however I had to connect as follows:
Motor Green to Loom Green
Motor Green/Red to Loom Green/Brown
Motor Breen/Brown to Loom Green/Red
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