Jchiodi

I have had intermittent problems with Pass. side window, finally stopped working altogether, I switched switches to see if I could get window up. No movement at all. (I have checked fuses).

Pulled door card... tested motor with test light. With test light grounded I have current to one side of motor terminals when pushing up, current to other motor terminal when pushing down. Does this guarantee that it's a bad motor?

If it were just locked up, I would blow fuse I would think. Is there anyway to close the window by cranking anything by hand? Like the headlights.. can't see anything to turn.

If I pull the motor I will try and bring it back to life, this does indicate it's bad?
Right? ( I am very bad with electrical problems)

thanks and I guess I'm too late for that half price sale, damn.

soontobered84

PM Blackshark. He's got some motors

Jchiodi

See what's what on it.. car is garaged till spring...

Does it definitely sound like motor dead?

soontobered84

Sounds like it to me. Some sort of open, anyway.

dr bob

The switches swap the power -AND- the ground to get the motor to reverse, so testing for power is only half the job.

The motors do 'gum up' with crud so it's worthwhile opening and blowing the crud out. Similarly, the grease in the little gear case seems to be more wax than lubricant as the years go by.

There's a thermal overload protection device in there somewhere too. I had a slightly sticking switch for a bit, and I could see the voltmeter swinging while stuck in traffic, and hear the motor energize and relax in concert. If the motor is stuck for some reason, the theraml protection thing will open the circuit.

Failure or fault with wiring seems to happen where it passes through the tube at the front, and just forward of that tube.

Were you testing for power with the motor still connected? A weak/damaged wire will look great to a meter when there is no load present.

soontobered84

Dr. Bob,
As you well know, I am no electrical wizard, but if he was testing power AT the motor, and had power in the appropriate wires at the motor at the appropriate times, doesn't that mean that he has some kind of open inside the motor?

That would sense to me, but then to me, everything electrical is magic anyway. That, and automatic transmissions!

dr bob

John--

Frayed or partially fractured wires will look great on a meter while the motor is not connected. With the motor as load on the circuit, the resistance in a wire will show up as low voltage at the meter. Hence the question. Was power tested from each motor lead to ground, or to the other lead?

A poor ground at the switch end will cause you to see what appears to be correct voltage at the motor even with the motor connected. To test the circuit including the ground side, connect the meter to both wires at the motor with the motor connected. The volt reading should be zero until the switch is activated. Once activated you'll see 'positive' voltage in one direction, 'negative' or reversed voltage on the meter with switch in the other direction.

With the motor disconnected, test the resistance through the motor itself via the connector on the motor side. If the resistance is high or infinite, look at the brushes or the thermal protection, respectively.

I haven't been inside the motor to see the thermal protection/overcurrent protection device, so can't describe testing it.

soontobered84

Thank you Dr. Bob. That makes it more clear to me what you meant.

The Deputy

Make up a couple long leads with alligator clips on both ends, approximately six feet long, and use them to diagnose the motor. Just find a 12 volt source and a ground post (there are a couple located above the fuse panel) inside your CE panel area...run a hot wire from the 12 volt source to one terminal of the motor and a wire from your ground source to the other terminal...motor should run in one direction. Reverse hot wire and ground terminals...and motor should run the opposite direction. If it does not...most likely the motor is bad.

Brian.

Jchiodi

I have taken motor out. And apart. I get continuity from one plug terminal to brush, and the same with the other terminal and brush. When I apply power to both terminals, nothing. No continuity between terminals?

bad motor? Not sure where it would be open?

docmirror

Clean the commutator surface. Use a white eraser and some carb cleaner. If the commutator is dark brown, it's got too much resistance. If that doesn't do it, Replace the brushes while it's apart.

dr bob

The commutator is the part of the armature (the part that rotates) where the two brushes connect physically to the windings in the rotor. As the armature turns, different cols wrapped around the armature have current passing through them. With that in mind, you can use your Ohm meter to test for continuity through each of those windings in the armature. With the brushes out, put your probes on the copper pads on the armature/commutator that sit under each brush. Should read very low resisitance.

At the same time, current is passed through the stator coils, the ones that don't rotate. With the brushes lifted, your ohm meter should read low resistance between the power input terminals, and also between the two brush holders.

--- The commutator is a series of brass or copper weedges, separated by phenolic or mica strips. These strips wear down at about the same rate as the copper pads do, so present a fairly smooth surface to the brushes. Sometimes the copper wears faster, leaving edges of the strips to hold the brushes clear of the copper pads.

You can do a little improvement on the commutator surfaces, including those separator strips, by using a little flint paper or emery cloth. Do Not Use Aluminum Oxide Paper, as the abrasive bits that are shed by the paper are electrical conductors an can wedge in the gaps where the strips are and short sections together.

Generally, you can wash any parts of the motor with detergent and water except for bearings. If you do this, plan on blowing as much water out s possible, then baking the washed parts in your handy garage toaster-over for a couple hours at maybe 150º.

-----

The motors work by generating opposing magnetic fields in the armature section and the stator coils. Those oppsoing fields will push the rotor relative to the stator coils and cause it to spin. The current passing through the coils causes heat. In extreme cases of extended use or sitting with current applied and rotor locked, the heat will be great enough to soften and maybe even melt the varnish used to insulate the windings. Along with the heat, the windings get mechanically jostled each time the motor is energized. With the heat, this will cause "winding shift" so that the magnetic fields no longer align correctly for rotation. The mechanical component of this causes the windings to rub against each other, eventually wearing through that varnish insulation and causing a short circuit between sections. None ofthat is good for the motor, really.

Jchiodi

Just to let you all know... it was a bad motor, got one from 928 international, and it works.

Also was an intermittent bad switch. I've got another one. Just can't figure out which wire is which to put on the plug! Figure there are 24 possible combinations for 4 wires to go to 4 other wires?

I can't remember if I posted before, but the pic shows the wire on the switch as green, but it is blue! Anyone hook up one of these before?

linderpat

Don't toss your old motor - they are rebuildable - I have always been able to repair mine. There is a good pictorial on how to do it (I can't find it right now). These are very robust parts and easily fixed, however.

Jchiodi

It's a 10 pinion gear type for sale cheap.....