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Simple AW4 Torque converter lock up question

Ecomike

NAXJA# 2091
NAXJA Member
Location
MilkyWay Galaxy
I need to know just how locked up the AW4 torque converter lock up is when it is working properly?

Is it a one way lock up?

In other words if you let off the gas, does the Jeep drivetrain turn the engine and keep the engine rpms elevated (two way lock up), like with a manual transmission, or does it slip and let the engine slow down even while the TC is still in the locked mode?

I have a TC lock up dash light on mine now so I can see when solenoid #3 is getting voltage to lock up the torque converter.

With mild acceleration mine seems to lock up, but at steady state cruise it seems to slip a little and during deceleration it is obviously slipping, but my lock up light is still on until I hit the brakes, or until the vehicle speed drops under 25 mph, or until the engine rpm drops to 700 rpm.

By slipping I don't mean the torque converter is bad, I mean it is not totally locked in a direct drive mode.
 
Typically TCCs are unlocked on decel to keep it feeling smooth and not like a man trans.
Is this lock up light an added on light?
Is so then it might be an idea to add a second light on the ground side of the TCC(solenoid 3) with the other end of the light going to ignition or acc pos.
That way you'll know the TCC is being commanded to lock when both lights are on.
Since both sides of that solenoid are switched, you need to keep an eye on both sides to know what's going on.
 
MisterFRjunior said:
Typically TCCs are unlocked on decel to keep it feeling smooth and not like a man trans.
Is this lock up light an added on light?
Is so then it might be an idea to add a second light on the ground side of the TCC(solenoid 3) with the other end of the light going to ignition or acc pos.
That way you'll know the TCC is being commanded to lock when both lights are on.
Since both sides of that solenoid are switched, you need to keep an eye on both sides to know what's going on.

What do you mean both sides are switched? Where did you hear that?

My tests and experience tell me that the #3 solenoid is directly grounded, not switched. Do you know something I don't?

I got a reading of 19 ohms across solenoid #3 using the hot feed wire and the engine body ground, with all power off, and the TCU disconnected, so that says it is grounded on one side with the power off.

The light is getting power directly from the same wire that solenoid #3 is powered from. I installed it. 12 volt LED lamp.
 
MisterFRjunior said:
I'll have to look that up tomorrow to make sure of what I said.
What year XJ do you have? 4.0, right?

'87, 4.0, 4x4, NP242.
 
All solonoids in the AW4 are directly grounded to the valve body. It switches on-off when 12 volts is applied or disconnected. I replaced all three in my AW4 a couple of years ago. Testing was by means of an OHM meter. High resistsance (do not remember the reading) = shorted solonoid, low resistance = solonoid is good.
To me, at about 50 MPH and above, the TC remains locked when you let off the gas ie: the RPM remains high until the brakes is applied. Driving around town say 40 MPH and below, the RPM returns to idle as soon as the gas is released. Exact numbers I do not have but I seem to remember when on the highway the RPM changes very little between (using the pedal not the cruise control) pedal on and pedal off going down hills or exit ramps.
I am sure there is someone who have more info than I do.
 
Thanks, I would appreciate it if some of you would check your numbers (RPM, Vehicle speed, and when and how it locks and unlocks behavior) today and post them here.

Thanks!
 
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