'67 & '68 Wiper Switch Rebuild Q

[Owen L.]

I took apart my '67 wiper switch (#1993394) to free it up and clean the contacts. I feel I'm missing an electrical insulator piece because I get 12v to the case when pushing in the washer shaft.

Simplistically speaking, there is a brass nipple placed on the end of the shaft that contacts the energized plate when pushed in. On my switch, this causes 12v current to flow through the shaft and to the case - that doesn't seem right to me. Should there be an electric insulator between the nipple and the shaft - like a fiber washer? I didn't notice a disintegrated washer in the case when I took it apart, but then I wasn't really looking for one.

[Owen L.]

Re: '67 In-Car Wiper Motor Testing

RE: 1967 wiper motor

In my studies, I think the voltage to the switch case is as designed because the switch is actually a grounding device. Since the wiper motor has constant 12v, it is activated by completing the ground through the various wires to the switch. (via Willcox tech info) The only way to complete the ground is if the switch transfers to its own case and to the instrument cluster. (via my reasoning)

Now, I'm thinking I may have a bad wiper motor: (scant electrical diagnosing knowledge)

• Circuit tester (w/voltage display) clipped to (-) battery post, key on, I get 12v on each brown wire at the wiper motor and washer motor.
• Circuit tester clipped to (+) battery post, key on, I get 12v at the light blue and yellow wires in various combinations as the switch is activated. The dark blue washer is difficult to test when alone so didn't do that. My thinking here is that if I supply 12v from the battery to the wires and they're connected properly the circuit will show as complete, which I believe is indicated.
• Same (+) post connection, I also get 12v when probing the wiper motor's ground wire.

Because all of the wiring seems to be carrying current appropriately (?), I'm thinking the issue is in the motor itself. I really can't get any sort of test leads on the motor unless I pull the distributor and all its stuff - which I just reinstalled after changing the intake gasket. No joy there.

Have I missed anything short of pulling the motor?

[Richard M.]

Re: '67 & '68 Wiper Switch Rebuild Q

Owen,

Yes the switch applies ground to the yellow and light blue wires for operation. Dark blue grounded for the washer. No 12V passes through the switch. Motor always is powered via Brown wire(Key ON via the ACC circuit)

You're reading 12V at the motor yellow/blue via your test light because it's reading the coil windings inside the motor.

Contacts are grounded (through the switch body to the cluster) for each function:


Yellow & light blue grounded = low speed
Light blue only grounded = high speed
Dark blue grounded (push button) = washer pump

At the motor, with Key ON, if you ground the blue or blue&yellow wires it should operate.

Edit.... you can do this at the switch connector under dash if you can't reach the motor terminals.

If not, it's the motor. Sometimes from long periods of non-use, the motor brushes stick to the armature. Sometimes a light rap on the motor housing will free it. If not it'll have to come out for inspection. Reference internal photos below.

Rich

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