38 LaSalle wiring question

[Tom Beaver]

The generator and regulator that came with my car are not original.  The voltage regulator I have (1118303) is a three element type without a starter safety relay.  My question is how do I now wire up the starter solenoid so that I can't engage the starter when the engine is running.  I assume the factory continued with this safety feature after they changed voltage regulator design but I don't have a wiring diagram for the later cars that may show how they did it.  Hopefully without a major rewire of the starting circuit.  Any help would be appreciated.

Tom Beaver

[vicbrincat]

Hi Tom,

The problem is that once you get away from "original" ..all bets are off. You are pretty much left on your own to improvise. The design where you can't re-engage the starter once the motor is running pretty much stayed the same for many years after your car was built...BUT...it did not continue forever..by the late 50's it was possible to re-engage the starter after the car was started...I know that my '59 was that way.

The original system used one side of the solenoid attached to the voltage regulator "G" (or "A" in some cases). If the generator was not turning, this point was at 0 volts or (ground) with respect to the +6v of the battery. That means that when you apply the starter button you would put  +6 volts on one of the solenoid terminals and 0 volts on the other...current flows..and it would engage.

Once the Generator started to turn, the voltage regulator ("A") would no longer be at 0 Volts..that means no potential difference can be made on the solenoid by engage the starter button...that's how you would stop it from re-engage once the car was running.

So that's how it worked....now how to fix your issue....without understanding the new components..it will be very difficult.

But you can try and recreate the original set up which should be possible if you are in fact still using a "generator" as opposed to an alternator. The only other choice is to install a relay which uses the output of the generator "A"  as one terminal and a connection from the "accessory" of the ignition switch on the other side of the relay coil. The relay contacts themselves would complete the circuit  between the solenoid and the starter button. But unless you have the right relay and you know what you are doing...this could be ...well dangerous! One wrong connection ad you will melt something..and even start a fire. You need to have someone who knows auto electric very well help you do this.

Good luck.
Vic

[Doug Houston]

Lemme kibitz here. The solution is really a lot simpler than installing another relay.

On the original generator regulator, there had been a terminal, as you've said, for the starter solenoid return to connect to, but with whatever regulator you now have, that's gone. The wire that used to connect to the safety relay, now hangs unused. The generator armature lead still is connected to the regulator, whatever kind you have. In the later model Cadillacs, the starter solenoid return wire connects to the generator armature within the harness.

I've seen this done on many cars, where a later generator regulator is installed. Simply, connect the starter solenoid return wire to the Generator armature terminal at the regulator, and you'll have the connection that was on the later model cars. Best to "ring it out" with an ohmmeter, or a test lamp, just to be sure you have the right wire connected to the gen, armature.

Another way of checking is to have the return wire loose, and someone in the car, holdiing the starter button. Nothing will happen until you ground the wire; then the starter will run. You will then be safe in connecting it to the armature terminal on the regulator.

[Tom Beaver]

Doug and Vic, thank you very much.  The starter solenoid return wire is there in the wiring harness and will be easy to connect to the generator armature terminal on the voltage regulator.  The explanation sure makes sense and at this point it will be essentially trivial to make the fix.  That's a pretty clever scheme for overriding the starter push button when the engine is running and every once in a while the fix turns out to be easy.  Now if I can just figure out what to do with the front turn signals -----
Thanks again.

Tom Beaver