C2 Wiper Motor Ground

[Jerry L.]

My windshield wiper motor on my 1966 is not grounded for some reason. When I run a ground wire direct to the motor housing, with the wiper switch on, it will work. Without the ground wire all I get is a clicking noise when I turn the switch on. I have checked the wire connectors to the motor and they are all properly attached. As I understand it the ground connector (Black wire) comes from the blower motor. The ground connector at the blower motor has two black wires one for the blower motor and the other that goes to, I assume the wiper motor. I have checked the wires to the blower motor and it has continuity to ground but, the ground connector to the wiper motor does not. I have checked the continuity from the wiper plug and the blower plug to the entrance of the wire harness, using a pin to penetrate the wire and they both check out. There is no appearance of physical or heat damage to the harness between the blower motor and the wiper motor or any other harness. First, am I correct in my thinking that the wiper motor gets its ground from the blower motor? Second, does anyone have an idea as to what the issue may be other than that wire being severed somewhere in the harness?

Thanks in advance,

Jerry Larsen
Morada, CA

[Wayne W.]

Re: C2 Wiper Motor Ground

The ground goes from the wiper motor to the heater blower to the black wire near the starter. It should be bolted to the starter mounting bolt.

[John H.]

Re: C2 Wiper Motor Ground

First, am I correct in my thinking that the wiper motor gets its ground from the blower motor? Second, does anyone have an idea as to what the issue may be other than that wire being severed somewhere in the harness?

Thanks in advance,

Jerry Larsen
Morada, CA

Jerry -

See your Assembly Manual, UPC 12, sheet A9, View "B"; the wire shown as "Black" under the head of the starter bolt with the negative battery cable is the bottom end of that pigtail that grounds the blower and the wiper motor. That wire is just a loose pigtail with a ring terminal on one end and the two female plastic connectors on the other end that's taped into that leg of the engine/starter harness, and isn't connected to anything else.

If the blower connector shows ground and the wiper connector doesn't, the wire is broken between the wiper motor and the blower motor; un-tape the harness between the two and repair it.

[Jerry L.]

Re: C2 Wiper Motor Ground



Thanks in advance,

[Stephen L.]

Re: C2 Wiper Motor Ground

Before you open the harness, perform a continuity check on the wire.

If you find the wire to be open, then carefully unwrap the black vinyl covering from the end to past the location of the other end of the black wire. Repair/replace the suspect wire and re-wrap the wiring using non-adhesive vinyl (available from many vendors). Blend wrap into the existing to minimize the new vs old wrap. Much cheaper than a whole new harness.

[Geoff B.]

Re: C2 Wiper Motor Ground

I am running into a very similiar issue with wiring at the wiper motor and washer pump. Do the wiper motor and washer pump each have a ground wire or is the wiper motor grounded through the body of the washer pump? I had assumed that the wiper motor was grounded by use of the small strap that is anchored to one of the mounting screws, but my wiper motor only seems to work if I also attach a dedicated ground wire to that same anchor point.

[Stephen L.]

Re: C2 Wiper Motor Ground

There should be a single black #18 wire with a female connector that plugs onto a male flat "stab" which is attached to the metal ground strip on the wiper motor. (See Photo for stab location). This wire goes over to the heater motor for the heater ground and continues down to the grounding point of the starter (starter to block bolt).

Probably this wire is open, or not properly connected at the starter end. If this wire is present it can be easily checked for continuity with an ohm meter. place one ohm meter probe on the metal strip and the other probe on a good ground on the block. It should read zero or within 1 ohm. If not, check the connection at the starter mount. If that looks good then thee wire itself has been damaged someplace.

[Geoff B.]

Re: C2 Wiper Motor Ground

Thanks Stephen! It looks like someone had replaced that stab with a wider one that doesn't fit into the connector coming from the ground that goes to the blower. The stab has a hole in it and has been mounted to the wiper housing, either that or they replaced the connector on the ground wire with a smaller one. Then the ground wire was plugged into one of the leads on the washer pump. If I can find the correct female connector to fit the stab, that will solve one problem. Next I'll have to figure out what they did with the wires for the washer pump since that never has worked.

[John H.]

Re: C2 Wiper Motor Ground

Do the wiper motor and washer pump each have a ground wire or is the wiper motor grounded through the body of the washer pump? I had assumed that the wiper motor was grounded by use of the small strap that is anchored to one of the mounting screws, but my wiper motor only seems to work if I also attach a dedicated ground wire to that same anchor point.

Geoff -

The washer pump has two wires - the brown one is power any time the key is on, and the dark blue one goes to the wiper switch; when you press the switch for washers, the dark blue wire is grounded through the switch body to the cluster housing, activating the washer pump. The wiper motor works the same way - it has power any time the key is on, and when you turn the knob, either one (high speed) or both (low speed) field coils are grounded through the switch body to the cluster housing, activating the wiper motor. There's no power at the wiper/washer switch - it just provides the ground for those circuits. The motor housing itself is grounded through the black ground wire (shared with the heater blower) that plugs onto the male spade terminal on the front of the motor. Diagram below shows how the circuits operate.


WiperSw67.jpg

[Geoff B.]

Re: C2 Wiper Motor Ground

Thanks John! With the info you gave me I tracked down the wires that had been cut and taped off, I was able to get everything connected. Wipers work at both speeds and the washers work. Neither of them were working before.