How does the Force Motor Work? - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums
 
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post #1 of 9 (permalink) Old 10-24-2018, 07:42 PM Thread Starter
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How does the Force Motor Work?

Does the plug to the force motor only work one way? I saw it was off, plugged it in, and now my transmission shifts slow, and there is no TCC lock up in overdrive.

The transmission was remanufactured by a local shop. Things worked great when I got it and installed it. But, it had a leak I wasn't aware of, and the same day I took it into the shop to be checked out, it ended up slipping in 3rd and 4th just hours later. I was told to put two quarts in it and try it out. I did and things worked fine. Went back to the shop with it and they determined the gasket would need to be changed. But, they weren't willing to do it under warrantee because I was the one who installed the trans.


I changed the gasket, but unbeknownst to me, I got the plug that goes to the force motor stuck inbetween the case and pan, crushing the plug. Not sure how it pulled off the force motor, but there it was. And, I only noticed it, because the pan was still leaking. So, I pulled it again to see the crushed plug. I used a screwdriver and opened the connectors back up and slid it over the terminals on the force motor, but I don't know which way they go. Now, the transmission shifts slowly between every gear, unless I have the throttle nearly floored. And, it seems the TCC is no longer locking up in OD.


Would this be a symptom of the force motor not working? Can the plugs be flipped and still connect to the terminals? Would the TCC not lock up if the force motor wasn't operating properly? Is there anyone with a PDF of the 4l60e GM service manual?

Thanks.
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post #2 of 9 (permalink) Old 10-25-2018, 07:02 AM
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Complete 4l60e info is provided by factory service manuals. Get at My Files

Also tell what year, engine, etc your car is. It helps us to help you.

I've never heard of any part of the 4l60e being called a force motor. The trans has logic switches which activate shift solenoids. And it has other pcm solenoids, like for tcc lock up. So what is a force motor?

Last edited by cocobolo95; 10-25-2018 at 07:06 AM.
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post #3 of 9 (permalink) Old 10-25-2018, 07:27 PM Thread Starter
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1995 LT1 Formula


Here's a pic of the force motor

https://www.bing.com/images/search?v...x=0&ajaxhist=0
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post #4 of 9 (permalink) Old 10-26-2018, 06:57 AM
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looks like a solenoid to me. But that's for the pulse width modulated torque converter apply.

Or the variable solenoid used to control pump pressure.

On DC electrics reversing the plug will reverse the action of the device. As an example. When my radiator fan motor is hooked up correctly, the fan runs so as to pull air through rad into engine compartment.

When hook up is reversed, fan runs backwards and pushes air out of engine compartment. While I've never reversed the leads on a solenoid, my guess is that a solenoid that pops outward would cease to work because the magnetic field created would be reversed.

Same for a solenoid that pops inward. Reversing the leads would reverse the magnetic field and cause no action from solenoid.

Last edited by cocobolo95; 10-26-2018 at 07:08 AM.
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post #5 of 9 (permalink) Old 10-26-2018, 07:25 PM Thread Starter
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It's the PCS. Yeah, I thought that if the plug was reversed it would reverse the operation of the solenoid. But, things I've read online are saying that the polarity shouldn't matter. IDK how that could be when it connects to a high and low control system. The wiring diagrams make it seem like it's a high pressure line and a low pressure line, not just a positive and negative circuit. Anyway, after Halloween I'll pull the pan again and flip it and see what happens. My biggest concern is if the pressure is low, due to the solenoid working opposite of what it should, would that keep the TCC from properly engaging? Everything was locked up tight from 1st though 3rd, but OD would act like it was slipping when I accelerated. It didn't do that while this solenoid was unplugged. So, like I said, I'll try and see what happens when I flip the plug.
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post #6 of 9 (permalink) Old 10-27-2018, 07:15 AM
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If fluid pressure is low, the components in trans won't function correctly. You should put a pressure gauge on the transmission port to see what pressure is. Service manual shows proper fluid pressures and where test port is located.

Besides wiring the correct polarity, the signal sent to them must have the correct on/off times for the solenoid to function correctly. Because the signal is a square wave sent by pcm, an oscilloscope would be needed to check on/off time of the signal.

Last edited by cocobolo95; 10-27-2018 at 07:19 AM.
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post #7 of 9 (permalink) Old 11-14-2018, 07:51 PM Thread Starter
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Ok. I was able to get a pressure gauge on the transmission tonight. It reads 55-56psi at idle, in park. When I put it in gear, it still remains at 55psi through shifting in all gears at light throttle. In park, a quick blip of the throttle will send pressure up to 100psi, but holding steady at higher rpm lets pressure drop back down to 55psi. Shifting from 3rd to 4th gives pressure readings of 55psi while at light throttle. Downshifting into 2nd will show a pressure increase while the gears are engaging and then fall back to 55 psi.

The service manual says to run the tech 1 scan tool to change the amperage to the PCS to check pressure. I don't have that. From what I'm able to find so far, it doesn't give me data on what pressure to expect while driving, or at different throttle angles and rpm.

What I did find the other day is that it is only slipping in 4th gear when it gets hot. At initial start up, when cold, everything works properly. Once it does start slipping, I will notice that it will upshift from 3rd to 4th just fine. Then when you try to accelerate in 4th it will slip until you hear it slowly start to re-engage. Also, when you decelerate in 4th to say 35mph, and then step on the throttle, instead of downshifting to 3rd right away, it just slips until rpms are up high and then it immediately kicks into third with a nice and tight lock up. During this situation, if I were to press down on the accelerator rapidly, it would downshift to the third immediately then, too. It is just when applying light throttle, and slowly pressing it down do I have this issue with slippage.

I'm going to take it to a shop to have the transmission scanned since my scanner won't read the trans.
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post #8 of 9 (permalink) Old 03-29-2019, 12:23 AM Thread Starter
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Well, it's been a few since I last posted. Here's what I found out. The plug can go either way, according to online articles, but the manuals show it going on a specific way. The awful performance from the transmission disappeared once I had the shop delete the transmission trouble codes from the computer. I don't have a scanner that will read those, unfortunately... Since then, everything has been working great for a few thousand miles.
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post #9 of 9 (permalink) Old 03-29-2019, 06:59 AM
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Glad to hear everything is working well. A transmission code also can affect the way the engine runs. As well as an engine code can affect transmission operation You should look through the code section of the 95 service manual. Each code lists what affects the code has..
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