I have an odd issue with a 2001 4L60E I built a couple years ago. I replaced all of the clutches, seals, bushings, TCC solenoid/harness. Added better clutches, sun shell and a Transgo shift kit. It has worked great until about a month ago when it stopped locking the TC and gave me a a shift solenoid code. Replaced both shift solenoids, TCC solenoid and harness. It shifts into 1,2,3 and 4 fine with a firm shift. But has no TCC and drops out of 4 to 3 then goes back to 4 after a few miles once and a while. When it goes back to 4 it is a normal feeling shift. I have a good scanner and have tried commanding the TCC to lock but it does not. Also when the trans goes back to 3 the scanner says the PCM is still saying B solenoid is on. I did pull the pins from the PCM for the TCC solenoid and PWM solenoid and they are both seeing 12volts. Did a amp on them and the TCC pulls about 700mAmps and the PWM solenoid pulls about 1Amp. When I grounded the TCC solenoid wire I could here the Torque Converter trying to lock but it would not. I looked at my service manual and there is a place where TCC fluid and 4th run side by side. Do you guys think I could have a leak that developed in the valve body gasket that involves both circuits? I just looking for some input before I pull this thing apart.

 

Not an odd issue for a 4L60E at all.

You will definitely find plenty of info in these forums, if searched.
There are multiple possibilities why this could be happening.

Have fun!

 

Did do a lot of searching but couldn't find any threads with issues like I have. Found ones with TCC not locking and random shifting from 4th to 3rd but not both together hence why I asked for some thoughts from the experts or someone that had seen the same combination of issues. I do want to add that this started during a no abuse drive. The fluid has never showed any sign of burning or debris in the pan.

 

Alright, well if there is going to be some trouble shooting... it should be started off correctly:

-Inspect the condition of the ATF... remove any debris with a Filter and Fluid change.
-Ensure that the ATF Level is FULL (meaning about 1/8" above the Oil Pan Rail).
-Add between half and One full Quart of ATF over Full to ensure that adequate Fluid is available for 4TH-Gear and Lock-Up (lots of Fluid needed).
-Take Line-Pressure readings at Idle and at 1,200-1,500 RPM in all Gear-Selector Positions.
-Record any Current DTCs or DTCs in History.
-Disconnect the Transmission Case Electrical-Connector, and ensure that the Transmission operates as if it is in 3RD-Gear.

I know you have started with some of these steps.
Continue them all.

Has the original AFL Valve-Train been replaced (aftermarket/ oversized)?

In 3RD-Gear, both the Shift Solenoids should be off.
I would command them ON and OFF with the Oil-Pan removed and listen for proper operation.
The B Shift Solenoid should not remain on in 3RD-Gear... that is an error or there is a Circuit leak.

Does the Transmission operate normally when the Engine/ Transmission are first started Cold?
... but become an issue onced warmed up?

Did you keep the PWM function of the TCC, when you installed the TransGo "Shift-Kit"?

 

Ok Thanks. I'll get the pressure readings in a few days. The TC never locks (cold or hot)and the random down shifting and up shifting does not start until the trans is fully warmed up. I don't believe the AFL has been changed unless it was part of the transgo HD2 shift kit. I did use the transgo valve for the PMW which I think it disables the circuit.

 

Took the pressures today.
Idle (650rpm) rear wheels on the ground.
Park: 65psi
Reverse: 85psi
Neutral: 65psi
Overdrive: 65psi
Third: 65psi
Second: 95psi
First: 65psi

1800rpm rear wheels in the air to allow trans to shift into selected gear
Park: 65psi
Reverse: 95psi
Neutral: 65psi
Overdrive: 65psi
Third: 65psi
Second: 105psi
First: 100psi

I was able to look at but not able to manual select Pressure Control Solenoid amperage. It appear to be in line with the pressures I was seeing. The 65psi readings had a PC amperage of 1.05amp and the 105psi had a amperage of .85amp. Couldn't do any other pressure test, I have a brake line leaking and need to fix it now before proceeding. Glad it happened in the driveway.

 

Those 1800 RPM pressures seem low. Try unplugging the round wire connector on the passenger side of the trans and repeat the 1800RPM test.

 

Not good at all.

Please do what BBond105 instructed, to see what the maximum Line-Pressure will be.

 

I'll try to pull the plug today after I fix the brakes. I did find out my HP Tuners can force amperage change in the scanner section for testing so I'll try that today also.

 

wheels in the air those pressures are pretty normal
there's no load...the ecm is going to control pressure there.
You need to check with wheels on the ground, parking brake set, and footbrake the thing in every gear and test that way. With load, the pressure will go up appropriately.
I would try that before I tried unplugging the thing

 

I was trying to foot brake it when the brake line let go. Not going to get it fixed today will try tomorrow. Thanks for the help everyone..

 

Well got the brakes fixed and did some more test. I used my HP Tuners today and controlled the current on the PC Solenoid. With 0 current the trans would hold 220psi. With .5amps it would hold 150psi. With 1.00amps it would hold 65psi. I set the current to 0 in all forward gear settings with wheels in the air so the trans would shift to the desired gear and the pressure held at 220psi and did not drop out of 4th. Still have no TC lockup no matter what the pressure is set at. If you still want me to see what happens with the connector disconnected I'll do that tomorrow (got to hot to do it today)

 

What are the TPS, MAP and MAF sensor readings?

 

Do not test this stuff with the wheels in the air.
It's not really a valid test.
you also likely won't be able to tell converter lockup with the wheels in the air.

 

Ok I'll do the test while driving. Though i am pretty sure the converter is not holding because when the PCM is commanding it locked I could rev the motor in 3th or 4th gears and the tach would rise in rpm before the speedo did. I also tried locking it with my scanner with no rpm change. Earlier I also tried pulling the pin from the PCM connector, verified I had 12 volts and amperage draw (.7 amps) when I grounded it. I could hear something happening but it would not even stall the motor at idle.

 

Didn't really look at the sensors because it is running fine with no misfires and the computer is commanding the shifts and TC lockup.

 

So I took it for a drive this morning with the pressure gauge hooked up. Boy did I get some looks with those gauges tyrapped to my windshield wiper. The pressures in all forward gears with moderate load was 130 to 140psi in the 1500 to 2000 rpm range. The pressures were that same whether manually shifted or if I left it in 4th and allowed the trans to do the shifting. Under light load pressures in all forward gears were in the 65 to 85psi. The pressures all appear to agreed with what the PCM is commanding when looking at the PC Solenoid current flow with my scanner. Still no TC lockup when the PCM commands it or whether I force it with the scanner.

 

Anyone with some thoughts now that I performed these test. I think I developed a leak between passages at the separator plate. There is a point where the 4th and TCC circuits run side by side.

 

I'm just going to throw this out there with the standard "Don't ask me how I know this" disclaimer.

If you haven't already checked, check your coolant temperature with a scan tool. If your thermostat is stuck open, the TCC won't ever engage, and it won't shift to 4th gear until higher speeds.

Your pressures do seem a little low, but check the coolant temp first and make sure your not chasing "operating exactly as designed."

 

I didn't look at the scanner temp but the gage was reading 195 to 200 deg and the PCM is commanding the TC to lock and the solenoids to operate correctly for 4th gear.