I am replacing my Windshield Wiper Motor. The old one worked OK, in terms of high, low, delay and park, however it was very slow even on high speed. So I just thought it was good prevention to put a new motor in while I had some down time.

After putting in the new motor. The blades no longer park in the down position on the cowl. They park in the middle of the windshield. They stop at the same spot each time, just not the right spot. Car is an 84 with external delay module.

I found the following diagrams for troubleshooting, but I don't understand what I'm testing.

It says to turn the key on, switch to off and check for open between terminal B and ground.
1. Am I checking the CONNECTOR, or the Motor?
2. If I am checking the Motor, which seems like what I should check, why does it matter that the key is on and the switch is OFF when the connector is disconnected?
3. Diagram says if LIGHT ON replace motor. Isn't light on the same as 0.0 ohms/continuity on the multimeter? If so why does 0 ohms at motor terminal B to ground mean its bad. When I look at the wiring diagram, to me it looks like B is connected to ground when in the park position. Am I reading the diagram wrong?

Thanks for setting me straight on this.

You may have a bad new motor. If it does not cycle properly and all.

new motor is likely wrong motor. Park switch is part of big gear and just where "slots" for the arm is on output shaft.
Or you put arm 180° from normal.

Old Motor is dirty or has electric problems.
Motor ground is in 1 mounting ear and often dirty/rusty causing low volts.
See my Cave, Electric Motors

Might be module and + wries have issues too but check that ground.
Pull out metal in the rubber to clean it and metal strip and car mount area. Coat w/ silicon or brake grease to keep out water.
If really bad then drill holes to attach a ground jumper not using mounting bolts.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Remove both wiper arms.
Cycle the motor off and on a few times.
Reinstall wiper arms in the 'REST' position.
Report back the results.

[This message has been edited by olejoedad (edited 01-21-2020).]

quote Originally posted by edfiero: After putting in the new motor. The blades no longer park in the down position on the cowl. They park in the middle of the windshield. They stop at the same spot each time, just not the right spot. Car is an 84 with external delay module.

quote Originally posted by olejoedad: Remove both wiper arms. Cycle the motor off and on a few times. Reinstall wiper arms in the 'REST' position. Report back the results.

Only good when arms are only a bit out when parked. Often mean only 1 or 2 notches when the arms meet pivots.

Old motor was good at parking and new motor work right except parking way on glass then adjust the arms to match new motor parking can break the arms, wiper trans, or whatever is weakest first time new motor is on.

best is to remove both motors.
remove the motor lever from car. (2 small nuts holding a ball joint.)
put lever on old motor and note where lever points too.
put lever on new motor. should be same as old motor ± a very small error. if not then have wrong motor. Catalogs are often wrong or right part number on box has wrong part in it.

When reinstall the arm in the car... Clean and coat small BJ w/ brake grease or other "water resistant" grease that won't easily wash out first clean the car.

[This message has been edited by theogre (edited 01-21-2020).]

Typical wiper motor ground.
Gets loose rust dirt etc.
Just push out rivet to check/clean/fix.
Loose, try changing 2 rubber parts.

CLICK FOR FULL SIZE

Some replacement motors come w/ all rubbers and rivets. Many only have the ground like shown and you switch 2 others from old unit.
Push rivets out to move the rubber.

I coat the mounting bolts after install on sump side w/ silicon/brake grease to prevent rust eating the holes.

[This message has been edited by theogre (edited 01-22-2020).]

I removed the new motor and compared new and old.
Both read closed circuit to ground on terminal B, so it doesn't seem like there is any electrical problem. Nothing is corroded. My car has been garage kept in recent years.

Next I'll try to reinstall the new motor and pay more attention about where the wiper arm bracket attaches to the motor shaft. Seems like it really only goes on one way, but will double check this.

Before you reinstall the new motor, try this...

Put a degree mark on the shaft splines with a paint pen. Apply 12volts. Does it cycle 90* (about) on the up stroke, then return the same path on the down stroke of about 90*?

Edit: Bench test it.

[This message has been edited by Tony Kania (edited 01-22-2020).]

Troubleshooting 101; If the only thing you changed was the motor, and then the blades won't "Park" in the down position, then the motor is most likely at fault. A) Check your connections, then B) put the old motor back in and see if it "Parks" the blades properly.

I have had 2 starters bad from the store, 1 heater core, 1 power steering pump, 1 distributor, and 2 master cylinders (In a row!) (parts were not just for my Fiero- also my 1972 Comet and 1973 Mustang)

Quality is hit & miss on replacement parts......

0Ω for B to Ground means Gear hit "Park switch" in Park position.
Anything else the motor is Not in park and should show 0Ω between A and B.

A is "12v" From wiper fuse to run Delay Module/board to run motor to Park.
B is Power to DM and "turns off" when motor is in Park.
C is Low speed and used by Wash Delay and Park circuits.
D is High speed.

C D and Ground is directly connected to run the motor.

quote Originally posted by Tony Kania: Before you reinstall the new motor, try this... Put a degree mark on the shaft splines with a paint pen. Apply 12volts. Does it cycle 90* (about) on the up stroke, then return the same path on the down stroke of about 90*? Edit: Bench test it.

This doesn't prove anything in this case.
First post shows the new motor not only works and does park but in wrong place. You can test the motor how ever you want and won't change the bold section I posted above.
Again, Either install motor w/ arm 180° wrong or very likely Motor gear and output shaft is wrong and activating park wrong for this car.

Wrong Park is often a motor made for other cars/trucks w/ motor mounted in different orientation. (And/Or the wiper trans is made different.) Say Fiero motor shell points to the lid latch and motor for another is 45° to 90° down from that. Same motor except gear and output shaft are different to activate park for this reason.

Both motor should parked when off. All you need is test I posted to see arms are in different spots or not.

Many motors can have the arms mounted 180° out. I think most GM units including Fiero can do this. Depending on wiper trans, When this happens should park at or nearly all the way to A pillar side of glass.
If parked less then that... likely motor is wrong for the car.

Note that you Forcing the arm to move can damage/break the gear but won't affect parking.
Gearing is a worm and gear and force the gear on the motor worm make a huge load. Most times is better to remove the BJ to wipers to get access to the arm nut when wiper trans cover that nut.
If nut won't come off fairly easy. hold the arm better then try.