4r100

[oldschool]

4r100 stall in reverse

I've got a 2002 4r100. had a leak in the cooler line and lost enough oil, it quit moving on the highway. shut it down, fixed the leak, refilled, and now it locks up in reverse, 2nd and low. from what i've read on other sites, everything pointed to TC and or oil pump. Check Pressures at idle and stall, and all were within spec. Have no codes. I pulled the pump, and it did look ok. replaced pump, TC and still had same issue. Replaced the solenoid pack with no change. I did change the PCM with another known good PCM with no change. Cant find anything on exactly how the TC lockup works. If oil pressure or fluid level is low, and TC locks up, does that mean that the TC lockup is spring applied, and oil released? The TC lockup solenoid lets pressure to release? so is there something in the valve body that could be plugged and not allowing pressure to unlock the TC? I haven't really found any systems operations or trouble shooting help anywhere.

 

[Tiha]

Is it the OEM trans? Meaning it has the PWM lock up control?

Or has it been rebuilt with an on/off TC control?

It kind of does sound electrical. Can you unplug the elect. connector and try it? See if it still locks up, which would point to something mechanical. Or if it does not lock up, then points to something electrical.

 

[6.0 Tech]

Stupid question, but is the fluid full? Pressure/fluid is pulled to lock the converter.


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[oldschool]

Ok, that's where I'm confused. If it takes pressure to lock the tc, why if it's low on fluid, or low on pressure, the tc locks?

 

[Tiha]

Air in the system compresses in the line. once it reaches someplace like the TCC apply clutch it expands and applies the clutch.

 

[6.0 Tech]

Ok, that's where I'm confused. If it takes pressure to lock the tc, why if it's low on fluid, or low on pressure, the tc locks?

The converter needs pressure to unlock the clutch, so if pressure is low, the clutch will be locked on. It’s backwards from what you’re thinking


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[oldschool]

The converter needs pressure to unlock the clutch, so if pressure is low, the clutch will be locked on. It’s backwards from what you’re thinking


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That's what I was thinking how it worked. So now, I've got pressure in spec in all gears and at stall. In fact, have a new pump, TC, swapped with a good PCM, new solenoid pack. I haven't checked the TC lockup clutch solenoid to see if the control wire from the PCM is grounded. If it isn't, Then is there a spool, or check, or something in the valving that could be stuck not letting the TC see pressure?? From what little info I can find on valving, I don't see anything in valving that could cause the TC to lockup. I'm guessing its gonna be something stupid simple when I find it, Just haven't got there yet. Could the turbine shaft sensor, or the output shaft speed sensor cause the TC to lockup?

 

[oldschool]

Stupid question, but is the fluid full? Pressure/fluid is pulled to lock the converter.


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not a dumb question, but yes, oil is full. in fact i've change filter and replaced oil.

 

[Mark Kovalsky]

The TCCC solenoid controls a spool valve that applies and releases the clutch. If the spool valve is stuck the clutch can be stuck on. If the wire to the solenoid is shorted to ground it will also lock the converter.

 

[oldschool]

The TCCC solenoid controls a spool valve that applies and releases the clutch. If the spool valve is stuck the clutch can be stuck on. If the wire to the solenoid is shorted to ground it will also lock the converter.

Ok thanks. So when the tc solenoid is grounded, it is activated and blocks pressure to the tc lockup clutch. When ground is lost, it deactivates, allowing pressure to go to tc lockup clutch,, which then releases the clutch. So it's like a normal open circuit? Do I have that right? If th solenoid ground wire is not grounded, then the only thing left I haven't mess with is the valve. Corect?

 

[Mark Kovalsky]

That is correct.