Another wiper motor question

[HIGHWAY BY THE SEA]

I just bought a new wiper motor for the 67 GMC 3500 that supposedly has the pump in it. Here is what they sold me:





Here is the one that is already in the truck:



Notice that the one in my truck has the three bladed connectors, and two more bladed connectors apart from those. The new one has the three bladed connectors, but not the extra two separate ones. Did I buy the wrong one, or is this some modern upgrade? This new one looks NOTHING like the old one.

[RodnRudy]

You only bought the wiper motor. You'll have to take your washer pump off the original motor and put it on the replacement motor. Take your original out of the truck and you'll see what I mean.

[LockDoc]

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This new one looks NOTHING like the old one.

If you take the plastic cover and washer pump off of your old one they will look the same.

LockDoc

[HIGHWAY BY THE SEA]

I told them I needed the washer pump when I ordered this at the store, so I assumed this was a model equipped with one. Duh!

[HIGHWAY BY THE SEA]

OK, I bought the ridiculously-expensive washer pump and installed it onto the new wiper motor. Now I cannot get the wiper motor arm crank off the old motor. I have soaked it in PB Blaster all day, but it will not budge. Does this require some special tool or trick?

[LockDoc]

Originally Posted by HIGHWAY BY THE SEA

OK, I bought the ridiculously-expensive washer pump and installed it onto the new wiper motor. Now I cannot get the wiper motor arm crank off the old motor. I have soaked it in PB Blaster all day, but it will not budge. Does this require some special tool or trick?

It should just pull off if you have the nut off. Try laying the edge of the arm on something solid like an anvil or the back of bench vise and rap on the edge that is up with a small hammer to break it loose. Mark the front of it with a felt tip pen so you know which side is out and make sure you get it on the new motor exactly the same as the old motor.....

LockDoc

[HIGHWAY BY THE SEA]

Just went outside and checked, and you were right there was no black wire attached. I found the detached black wire and attached it but the wiper still does not work.

[LockDoc]

Originally Posted by HIGHWAY BY THE SEA

Just went outside and checked, and you were right there was no black wire attached. I found the detached black wire and attached it but the wiper still does not work.

Did you have the ignition switch on when you tried it?

LockDoc

[HIGHWAY BY THE SEA]

Originally Posted by LockDoc

Did you have the ignition switch on when you tried it?

LockDoc

Yes. I am leaving town tomorrow, and will not be able to work on the truck until next week.

[LockDoc]

Originally Posted by HIGHWAY BY THE SEA

Yes. I am leaving town tomorrow, and will not be able to work on the truck until next week.

I will do some thinking while you are gone.

LockDoc

[Fbks_Cruiser]

As LockDoc mentioned in post #10 check that the switch is tight in the dash. It has to be tight as it completes the ground side of the circuit from that black wire. I went through this a while ago. Wiper motor didn’t run properly turned out to be ground issue.

[HIGHWAY BY THE SEA]

Anyone know off of the top of their head what size nut attaches the wiper crank to the motor? I had mine in a box on the truck's flatbed with other parts, and when I left to get a drink then returned minutes later the box was on the ground with parts scattered everywhere (I suspect the cat). I found all the parts EXCEPT the wiper crank retention nut. Once I know the size I will get another from the hardware store.

[elf w/capital T]

I just removed mine, your missing the pump and the gear from the motor, under the three terminals...

[HIGHWAY BY THE SEA]

I tested the wires that attach to the wiper motor today, and they do not have power. I also checked the power at the fuse box, and there is none there either.
And I still need to know the retention-nut size for the "crank".

[HIGHWAY BY THE SEA]

The wiper switch seems to test as "bad" so I am buying another one. This one sometimes did not want to turn off.
I also made a lucky guess and got the correct size retention nut for the wiper crank to replace the one that got lost.

[HIGHWAY BY THE SEA]

After a year of not working on the GMC much I have recently been tackling all the things that overwhelmed me last year. I intend to attack the wiper motor again tomorrow if the (CENSORED) rain will stay the Hell away. If it bench tests good I will then attack the grounding issues.

[LockDoc]

Originally Posted by HIGHWAY BY THE SEA

After a year of not working on the GMC much I have recently been tackling all the things that overwhelmed me last year. I intend to attack the wiper motor again tomorrow if the (CENSORED) rain will stay the Hell away. If it bench tests good I will then attack the grounding issues.

Look at the Brown wiring connector on the picture I posted in post #12 it looks to me like yours is plugged in with the Yellow wires on the wrong side of the connector. Try flipping that connector over so the Yellow wires are on the other side like my picture shows.

LockDoc

[RustyPile]

This has been going on for a year, it's time we get those wipers working..

The yellow wire comes from the "Ignition on" terminals in the fuse box and carries voltage to the wiper motor.. The switch provides the ground path through the 2 blue wires for each speed.. The switch HAS TO BE GROUNDED TO THE DASH.. The yellow wire is hot with the ignition switch in the ON position.. If there is no voltage present on the yellow wire, there is an open (as opposed to a short) or bad connection somewhere.. Find the open, (don't forget the fuse and it's connections) repair it, and the wiper motor should work..

[Andy4639]

Originally Posted by RustyPile

This has been going on for a year, it's time we get those wipers working..

The yellow wire comes from the "Ignition on" terminals in the fuse box and carries voltage to the wiper motor.. The switch provides the ground path through the 2 blue wires for each speed.. The switch HAS TO BE GROUNDED TO THE DASH.. The yellow wire is hot with the ignition switch in the ON position.. If there is no voltage present on the yellow wire, there is an open (as opposed to a short) or bad connection somewhere.. Find the open, (don't forget the fuse and it's connections) repair it, and the wiper motor should work..

Good info. The wiper is hot all the time. The dash switch makes ground for it to work. You have to have the wiper switch grounded to the dash for it to work.

[RustyPile]

Just so everyone is clear on this point: The yellow wire is hot only when the ignition switch is in the ON or ACC. position..

[HIGHWAY BY THE SEA]

Originally Posted by RustyPile

Just so everyone is clear on this point: The yellow wire is hot only when the ignition switch is in the ON or ACC. position..

Yes, I tested them with a meter today, and they are both hot when I turn the switch into the ON position, but not the ACC for some reason. Mine is a 67, but the ignition is 68 & up.
I am beginning to believe that the new wiper motor itself is bad because I have already checked the ground for it multiple times, and used a ground jumper wire directly to the body (and negative battery terminal). Looks like I will be removing the motor today if the rain stays away.
This thing worked very poorly when I first installed it (too slow, then NOTHING) so on to the next thing...

[HIGHWAY BY THE SEA]

I traded in my non-working wiper motor for a new one that bench-tested operational.

Then I tested my wiper plugs with a volt meter today. Here is the output (set on 25 DC)


Here is the meter (set on 25 DC) directly on the battery posts. The output is far more than on the wiper plugs. Is this normal?

[RustyPile]

As stated above, voltage is fed directly to the motor from the fuse box, and the switch provides the ground.. If you're checking voltage on the plugs at the switch, you'll get readings below battery voltage because of resistance in the motor windings.. Your test only verifies that you have voltage applied to the motor.. Does nothing toward testing the motor or switch..

It appears you still don't understand how the system works.. Read my first post in this thread again...

[HIGHWAY BY THE SEA]

Originally Posted by RustyPile

As stated above, voltage is fed directly to the motor from the fuse box, and the switch provides the ground.. If you're checking voltage on the plugs at the switch, you'll get readings below battery voltage because of resistance in the motor windings.. Your test only verifies that you have voltage applied to the motor.. Does nothing toward testing the motor or switch..

It appears you still don't understand how the system works.. Read my first post in this thread again...

Yes, I most certainly do NOT understand how this system works.
I have proven that the wiper motor works bench-tested, that I have sufficient power running to it, that my wiper wire plugs are good, that it is hooked up correctly (wiring diagram confirmed), that it is properly grounded, that I have a brand new wiper switch, and with all of this I STILL do not have a wiper motor that works when hooked up to my wiring!!!!
I re-read your post, and as far as I can tell I have done everything correctly, and I TOTALLY do NOT understand any of this because this thing is not working!!!! This is very frustrating to me, because I no longer know what else to do.

[RustyPile]

Ok, I understand.. Electrical stuff can get confusing.. Those electrons running through the wires are invisible.. Unlike water, we can/t see where they're going when they leak out..

Let's try this again.. The yellow wire at the wiper motor carries voltage (those electrons) straight to the wiper motor.. It doesn't go any where else (no switches) nor does it stop (go through a relay) along the way.. It's hot only when the ignition switch is in the ON position, or in the case of later models, it's hot also when the ignition switch is in the ACC position... For now, let's not worry about the ACC position.. The reason for this design is so that when the wiper switch is turned off the wiper motor will continue to run until the wipers reach their park position..

There are 2 sets of windings in the motor -- one for high speed and one for low.The windings are not grounded in the motor. Instead, the ground side of the windings are carried through the harness to the wiper switch.. When the wiper switch is turned on, it provides the ground path for the winding speed selected.. As such, the wiper switch must be firmly grounded to the dash.

Disconnect the harness at both the switch and wiper and test each wire for continuity.. There are three wires -- dark blue, light blue, and black.. Disconnect the battery for this test. If there is voltage present on the wires, you can ruin the voltmeter.. Set the volt meter for continuity, and probe each wire.. You should see full scale needle deflection on an analog meter, or in the case of a digital meter, an audible alarm..

IF you have good wiring, good motor, good switch, and a GOOD ground, your wipers should work.. .