Quarter Window Lift Motor Help

[Samplingman]

‘70 300 Convertible. I’m trying to get the left rear window lift motor to work. Motor works great up and down when I jump it from the battery. I used a test light and got power through the switch to the wire going to the motor. Both master switch and the individual switch were tested and route the power correctly to the wires. But when I connect the wires to the motor wires, the motor does not work, I get a very slight tick but nothing more. All other windows go up and down with the master switch and the individual switches. What could I be missing, what more could I test?

 

[FURYGT]

Has the grease in the mechanism hardened preventing the motor from being able to move the window?

 

[Camshaft]

This is my favorite topic. Lets do this. You have the motor out and bench tested it and it spins freely? Did you remove the cover plate to the drive gear on the motor and check out the guts to see their condition? They can get gummed up badly or the pucks ( if your PW motor has them) can be all beat up. If you take off the cover plate, which is the one tiny phillips screw, and all is clean and greased, and the motor runs smoothly on the bench, it could be that one, or more of the plastic rollers that guide the window regulators is broken or has popped out of the track that it runs in. Happened to me.
Once you have determined that the motor is clean and runs freely on the bench, connect it to the green and purple wire coming out of the rear window opening and power it up, and run the motor with the switches while the motor is laying on the floor of the car.If it runs nice and smooth then either the motor does not have the strength to push the window up, or there is something impeding the window from going up the slides. Sometimes the slides are clogged up with something, or more likely, one of the plastic rollers have broken off or are jammed in their running slots. The First photo shows my rollers, with bottom one broken off. Mine is a 67 300, but I imagine the sliding mechanisms are similar.

 

[Samplingman]

This is my favorite topic. Lets do this. You have the motor out and bench tested it and it spins freely? Did you remove the cover plate to the drive gear on the motor and check out the guts to see their condition? They can get gummed up badly or the pucks ( if your PW motor has them) can be all beat up. If you take off the cover plate, which is the one tiny phillips screw, and all is clean and greased, and the motor runs smoothly on the bench, it could be that one, or more of the plastic rollers that guide the window regulators is broken or has popped out of the track that it runs in. Happened to me.
Once you have determined that the motor is clean and runs freely on the bench, connect it to the green and purple wire coming out of the rear window opening and power it up, and run the motor with the switches while the motor is laying on the floor of the car.If it runs nice and smooth then either the motor does not have the strength to push the window up, or there is something impeding the window from going up the slides. Sometimes the slides are clogged up with something, or more likely, one of the plastic rollers have broken off or are jammed in their running slots. The First photo shows my rollers, with bottom one broken off. Mine is a 67 300, but I imagine the sliding mechanisms are similar.

View attachment 723373

Yes, last year I had both quarter window assemblies out, cleaned and greased up. I took the motors apart cleaned all the crud and repacked the grease. After reassembly I bench tested everything then put it all back together, testing the motors with direct battery power and they moved strongly up and down. It’s when I connect the wires from the harness the motor doesn’t budge, even though there is power as seen with a test light. I could remove the motor again and see if it spins with the switch outside of the quarter, but I’m thinking this is somehow electric and not mechanical.

 

[Big_John]

even though there is power as seen with a test light.

Having power is the first thing to test, but you can still light the test light with bad wiring.

Think of a piece of stranded wire. Connect one end to a battery and check the other end for power with your test light. Looks good right? That would probably drive the window motor. Now take that stranded wire and cut all the strands except one. Still lights the test light, but it won't pass enough current to drive the window motor.

So, if you can get the window motor to work off direct battery power, where you have plenty of current flowing through some jumpers. Connect it to the car wiring and there's not enough current to drive the motor, so you want to start looking for a bad connection, bad wire or maybe a bad switch limiting the amount of current.

 

[Samplingman]

Having power is the first thing to test, but you can still light the test light with bad wiring.

Think of a piece of stranded wire. Connect one end to a battery and check the other end for power with your test light. Looks good right? That would probably drive the window motor. Now take that stranded wire and cut all the strands except one. Still lights the test light, but it won't pass enough current to drive the window motor.

So, if you can get the window motor to work off direct battery power, where you have plenty of current flowing through some jumpers. Connect it to the car wiring and there's not enough current to drive the motor, so you want to start looking for a bad connection, bad wire or maybe a bad switch limiting the amount of current.

Good point, I’ll need to test the current out of the wires. I swapped out the switch and wire loom to the right side and it worked fine so I think that part is good.

Instead of pulling the motor I grabbed another spare that I knew worked and tested that one through the harness and switch and it only moved in one direction, so current going the other way might be weak. There is also something in the wiring diagram that shows a lock-out switch for service, but I have yet to find in the physical wiring harness.

 

[Samplingman]

Update! After @Big_John’s suggestion, my son began testing the circuit (I couldn’t figure out that damned multi-meter) and figured out that the main switch was not allowing current through. My options were replace or rebuild. NOS is $400+, repro is $200, rebuild is $165 and the incorrect but acceptable later switches are $75. With nothing to loose, I decided to rip into it myself to try and correct the issue. Now I know why the FSM says “bad switch, replace it”, lol.

I searched but couldn’t find any pics on what this thing looked like on the inside, so figured I’d post some here.

Removing the switch bank from the housing was a bit tricky, trying not to break the pot metal tabs.

Each one of the rockers are riveted to the base so breaking one of those would have made the job much harder. Look at all those contacts that are also riveted I place. $165 rebuild was starting to look like a better idea.

I decided to try and clean the contacts as best I could focusing to the most corroded one, the left rear switch. With an angled pick, jewelers file and a lot of contact cleaner, I was able to get it working.

Next up were these little thin wire springs that fell out or disintegrated when I opened it up.

I needed a source for these little buggers and after some searching I settled on some new bristles from a wire brush. They were the same thickness and had just enough spring action to work.

Here is where they contact the switch rocker, along the ridge of the rocker. I placed one to see if it worked.

You have to sneak them in between and below the contacts. It took a couple of tries, but I was able to get them all in and stay in place while I carefully snapped the bezel back in place.

Final step is to bend the pot metal tabs back to lock everything up.

 

[MoPar~Man]

What I would have done first is jumper power directly to the motor leads. Connect one motor lead to the body (some convienent ground point) and the other lead to the center pin on the switch connector. Reverse the leads if the window isin't moving.

The little spring wires don't play any role in the actual electrical functionality of the switches.

In the past few days I was putzing with the non-operation of my rear windows. One motor was not functional - but worked fine after I took it out, took it apart, and cleaned the junk around the armature contact and brushes and bearing area. Interesting internal circuit breaker mechanism it has. It's important to set the backlash correctly or they won't spin freely.

I ended up soldering a new set of wires directly to both rear switch pins, removing the connectors from the situation. These connectors can be a PITA.

 

[Samplingman]

You are correct. The springs are only there to help return the switch to center. Without them the switch flops around but does not affect the electrical functionality.

Interesting, I did not see an internal circuit breaker when I had the motors apart, but something cuts the power at the end of travel, that must be it.