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.

[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.