Early and late wiper motors are wired differently!, So THAT'S why the fuse blows! Options

[bondo]

I've got a 1970 914, and the splines on the wiper motor shafts were hosed. I installed a later wiper motor, (well, jkeyzer did it) and expected it to work. The terminals arranged the same, and it LOOKS like it's a straight swap.

The early switch supplies power in the off position on a green wire with white stripe. This goes to pin 31b of the wiper motor. This appears to be for the purpose of parking the wipers after the switch is turned off. On the early motor, this wire goes into the third terminal of the wiper's internal rotary switch.

The late motor still has 3 terminals on its internal switch, but the third one is not used, and terminal 31b goes to the second terminal. The unused terminal is grounded to the case. I opened up a spare late motor, and found that the internal switch grounds pin 31b. Grounding a hot wire of course leads to fuse blowage.

Does anyone know a way I can rewire this late motor to an early car, so I can use it? Here's the catch. The fresh air box and gas tank are already in, and the tank has gas in it. I'd REALLY like to figure out a way to rearrange the wiring at the motor and/or the switch that doesn't involve removing the motor. (IMG:style_emoticons/default/smile.gif)

I've looked at early/late wiring diagrams, and so far all I've done is give myself a headache. The car is a 70, and the motor is unknown, but clearly different.

[JPB]

Thats cool, good news and thank God foe fuses. It reminds me of how wrong folks are to jump a fuse with wires or pennies. (IMG:style_emoticons/default/beer.gif)

[bondo]

Ok, got it figured out. I had it wrong, the switch doesn't supply the green/white wire with power, it grounds it. The wiper motor supplies the green/white wire with power.

The late switch connects the green/white wire to the black/blue wire (low speed motor winding) when off. This connects the parking circuit, which turns itself off at the motor when the wipers get to the right spot.

Unfortunately I have an early switch, which grounds that green/white wire. If I connect that green/white wire to the black blue wire, the wipers park fine. But then when I turn on the wipers, they try to park every time they get to their parking spot. This is clearly hard on things, as the wires get warm.

My solution will be to use a relay that only connects the green/white wire to the black/blue wire when the switch is off. That should translate the function of the early switch into the function of a late switch.

[geniusanthony]

I am in the same situation, I replaced my early 71 wiper rack complete with motor with what I can only assume is a late model rack. The reason for replacement is that the bushings were dead/ovaled in my early rack.

Exactly what is happening is this; wiper speed 1 and 2 work fine but when I set the switch to park the fuse blows (# 9 if memory serves..25A) connections are as per Hanes manual terminals 31, 53, 53a, 53b,

I have yet to really look at the prints but if anyone else has run into this problem?

[geniusanthony]

I took some time to figure out the motors and why they are different, see pic

[geniusanthony]

I would hazard a guess that the contacts are the same within the housing, I don't really want to dismantle two working motors to verify his though. The diagram shows the motor, with high and low speed windings, and the terminal blocks that lead to the contacts.

OT but, I used some crap freeware to resize and I am sure there is something better out there without the lame copyright watermark. What do you use that's better?

[geniusanthony]

What the diagram shows:
Chassis to wiper spade lugs
53a red/black
31b grn/white
53 blu/black low speed winding
53b prp/black high speed windings

_____________

31b to TB3(early)
31b to TB2(late)
53a to TB1=same
53b to high speed motor windings
53 to low speed motor windings but through

the TB2 post

[TravisNeff]

Who the hell are you? (IMG:style_emoticons/default/poke.gif) (IMG:style_emoticons/default/biggrin.gif)

[geniusanthony]

So yah, I may have fallen off the "world" lately but I still lurk plenty. (IMG:style_emoticons/default/smile.gif)

[HalfMoon]

Hmm. Well I'm experiencing a slightly different problem in a 1973. My high speed doesn't work. I took a spare motor I had and hooked it up for test and it didn't work either (yet when I bench tested it it worked on both low and high). I might add, the colum switch is brand new (in an effort to solve this problem).
Soooo, my question is this-How can you visually tell a late model or early model wiper motor. I suspect the reason for no love with my spare is that it's incompatable (early).
Thanks,
David
As an aside, Shouldn't I be able to hotwire black with blue strip (I believe that's the high side on a 1973), the terminal that is, direct to the battery and see the motor operate at high speed?

[bulitt]

Make sure you have the wires on correctly
Pics of wiper wiring

If you want to check the motor-

Benchtesting a wiper motor- Link

[HalfMoon]

Make sure you have the wires on correctly
Pics of wiper wiring

If you want to check the motor-

Benchtesting a wiper motor- Link

Some more testing. 53 is the slow and 53b is fast and I was able to hotwire direct to test. Motor is fine so testing has determined that I'm having a power problem at 53b. Next test, circuit test on 53b's wire from motor to switch. I'm pretty sure I'm going to find a fault cause the switch is known to be good.
Thanks Bullit!