[R 70 Judge]

My windsheild wipers don't work on my '70 Judge. I've changed the fuses and it keeps blowing them when I try to turn them on.(Sounds like a grounded power wire to me)

Is there a common spot where the wiper wiring get pinched on a '70 A body?

What is the fuse rating supposed to be?

Thanks

[R 70 Judge]

My windsheild wipers don't work on my '70 Judge. I've changed the fuses and it keeps blowing them when I try to turn them on.(Sounds like a grounded power wire to me)

Is there a common spot where the wiper wiring get pinched on a '70 A body?

What is the fuse rating supposed to be?

Thanks

[61man]

can you disconnect the wiper motor at the firewall and see if it still blows a fuse, that should tell you if it is a shorted wire. If it doesn't it is probably in the wiper motor.


http://kurtspontiac.homestead.com/Pre1964Pontiacs.html

[78 GHOST]

R 70: Do you have a complete wiring diagram? I'd send you a copy if I had a danged scanner.

The wiper uses a 25A fuse as circuit protection.

I had nightmares sorting out this very problem on my 70 GTO. I bought a very expensive wiper motor before I discovered the problem was in a different area. I'm assuming that you've verified the wiring connector at the firewall is tightly connected and that all grounds are present and in good condition. The testing below is dependant upon having full system voltage available. Also, and most important is that you've confirmed the wiper linkage is free from binding and moves without undue effort. Binding and rusted linkage can easily cause a blown fuse.

Your first step is to understand how the wipers work: Basically, the wipers are supplied 12V from the wiring harness at all times the key is ON. The current flows through the wiper motor, back into the wiring harness, to the wiper switch, and to ground completing the circuit.

When the wiper switch is OFF, the contacts within the switch are open preventing the current from reaching ground and completing the circuit, thus no current flows through the motor and the wipers don't move.

When you turn the wiper switch to LO, the current must pass through a "shunt" (resistor) and then to ground. The shunt prevents full system voltage from passing through the motor thus causing the low speed wiper sweep.

When you turn the wiper switch to HI, the current passes directly to ground at full system voltage causing the high speed wiper sweep.

What I would first do is to fabricate a "jumper harness to be used to test the motor on the car independant of the vehicle's wiring harness. You would be wise to include a 20A inline fuse in the positive lead. With the fuse inline you won't start any fires!

Also, fabricate a "ground" test lead. For this lead, you will need (3) alligator clips, a short section (approx 4") of wire, and a longer (10") section of wire. However you do it, you need a jumper that resembles a "Y" in order to access the appropriate terminals. I like to use color coded wire to help avoid a shocking experience (yellow for hot, black for ground).

Pull the molded plastic wiring plug (from the wiring harness) off the wiper motor and examine the group of three terminals on the motor. According to the shop manual, the terminals are numbered 1-3. If you can imagine the central axis of the motor, the terminals are perpendicular to, and at the "top" of the motor just below the washer section (black plastic). Terminal #1 is on the far right, #2 is center, and #3 is on the "left" and closest to the centerline of the motor axis.

First, connect your "Hot" lead to the center (#2) terminal on the motor. Leave the battery side of the "Hot" lead disconnected for a moment. Then, connect the "Ground" jumper to solid metal on the wiper housing, then connect your remaining (2) alligator clips of the "Ground" jumper to terminals #1 & #3. Finally, connect the "Hot" lead to the battery making certain you have a 20A fuse in place. At this point, your wipers should be running in LO speed. If you disconnect only the "Ground" lead to #3 terminal, you should bypass the shunt and have HI speed. Reconnect the "Ground" lead to #3 terminal, then disconnect the #1 lead and the wipers should turn off.

If this is satisfactory, you can verify the health of the motor by measuring the amount of voltage flowing throught the motor using an Ammeter connected inline with the "Hot" lead.

According to the manual, LO speed should result in a crank arm rotation rate of between 35-45 RPMs at a current draw of 6.0 Amps (Bench test with no load) On car check with a wet windshield, the current draw should not exceed 6.5 Amps.

The HI speed circuit should result in a crank arm rotation rate of between 65-85 RPMs at a current draw of 4.5 Amps maximum for a no load bench test. The on car wet windshield Amps should not exceed 5.0 Amps.

The Amp values seem to contradict the motor activity, but remember that a stalled electrical motor, or a motor with a shunt or other resistance will raise the Amps indicated.

Hopefully, your wiper will be defective as this is the easiest fix. In any event, at this point you can safely rule out the motor as your problem.

Strangely, the wiper system incorporates wiring through the ignition switch and if you have had an incorrect switch installed in the past (don't ask how I know this) the wipers and other functions will not work.

If the above doesn't help, you need to verify you are getting 12V to the wiper motor. Once you've established the integrity of the power supply, you need to verify the pathways to the switch (ground) are in good condition.

Good luck and feel free to drop me a line at:

airdoc68@aol.com or airdoc68@kingwoodcable.net

-Matt

____________________________________
"Gee, what's that goat doing way up here in a cloud?" -Gary Larson

TO THE MILITARY FORCES CURRENTLY ACTIVE, AND THOSE THAT HAVE SERVED; THANK YOU FOR YOUR SACRIFICE FOR FREEDOM. PLEASE COME HOME SAFE.

[78 GHOST]

DOH!

[R 70 Judge]

Thanks 61 MAN & 78 Ghost

I'll give it a try this weekend.

[78 GHOST]

Any luck?

____________________________________
"Gee, what's that goat doing way up here in a cloud?" -Gary Larson

TO THE MILITARY FORCES CURRENTLY ACTIVE, AND THOSE THAT HAVE SERVED; THANK YOU FOR YOUR SACRIFICE FOR FREEDOM. PLEASE COME HOME SAFE.