4l60e no lockup

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#1
Make
Chevrolet
Model
Camaro
Year
1997
Miles
200000
Engine
LT1
I'm having this nightmare with a 4l60e where I have no lockup.

I've verified the computer is commanding lockup, and checked the solenoid actuates when the computer commands lockup. Also when commanding lockup manually with tech2 I get nothing. Have replaced all solenoids also.

I replaced the entire valve body and torque converter and still no lockup.

All gears work fine and the only trouble code is p1870.

This is doing my head in, any help appreciated.
 

bp042665

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#2
ok have you checked the o ring on the input drum also check the bushing in the stator tube to make sure it's not leaking past also the check ball at the tip of the input drum
 
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#3
Thanks for your response!

I actually replaced the whole input drum assembly on second tear down, so pretty confident it's not the check ball in the input shaft.

Confirmed o ring on input shaft is in place and replaced second time.

I replaced both bushings on stator twice and am sure they are correct.

This issue is very bizarre.

I am just in the process of blocking the apply valve in the stroked position to see if the engine stalls when I start it.
 
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#4
So I just blocked off the apply valve in the apply position (stroked) and the engine wouldnt stall. There may have been a tiny bit of hesitation but nothing noticable when putting it into drive.

The only thing I can think of at this point is to replace the pump
 
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#5
I always follow bp042665 as I want to learn to print money repairing CLEAN transmissions delivered to my garage. Yes a rich fantasy life.

That said I looked at the tree for P1870 - lots of checks and questions
Any other codes?
If p1870 was set the test above would be compromised as the PCM restricts TCC engagement.
Before condemning the pump I would think to put a gauge on the trans to ck pressures as p1870 commands full .
 
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#6
Lol yeah don't we all.

I've gone through all the troubleshooting steps for p1870 and I can confirm there's no gear slipping, just nobody home when lockup engages.

I get p1870 inhibits lockup but I've bypassed that by commanding it with tech2, and by paralyzing the valve in lockup, and there's definitely no lockup at all.

I have hooked up a pressure gauge and the readings are fine.

Pressure readings are:

At idle:
Park - 55psi
Reverse - 85psi
Neutral- 55psi
Drive - 55psi

Commanding PC solenoid in park:
1.07a - 55psi
1a - 55psi
0.9a - 70psi
0.8a - 100psi
0.7a - 130psi
0 6a - 155psi
0.5a - 175psi
0.4a - 185psi
0.3a - 190psi (gauge jumping +/- 5psi ish)
0.2a - 190psi (gauge jumping +/- 5psi ish)
0.1a - 195psi (gauge jumping +/- 5psi ish)
 

billr

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#7
How about R, can you get 325 psi in R with 0.1A on the solenoid?
 
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#9
The tech2 wont let me command the PC solenoid values in reverse or drive. Seems to only work in p or n. Checked the tech2 manual and that appears to be by design. I reversed it up my driveway holding the gauge and it went up to 290ish at medium throttle.
 

bp042665

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#10
can you command full lock up with tech 2 if so did it lock up if not you might have a bad converter it's rare but I got a reman 1 once with out the lock up in it was boxed wrong built for drag racing and they leave it out
 
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#11
When I command full lockup with the tech2 I get nothing. When I block off the tcc apply solenoid and valve in apply the engine wont stall. The pump passed a vacuum test.

I was adamant it was the torque converter but I replaced it twice with a known good one and still no lockup.

Are there any air tests I can do for the tcc circuit? I read in an old car magazine found through Google that you can apply air to the input shaft and stroke the valve and listen for a major exhaust leak. I did this and could hear the leak indicating the release circuit was working correctly.

I've replaced the separator plate and gaskets also twice with no improvement. Maybe there's a break in the casting somehow
 
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#12
I think I'll give it one more shot and replace the pump. If that fails, I'm just going to junk the trans and buy a new one. Probably throw it off a cliff in a fit of rage
 

bp042665

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#13
ok I did find a Bulletin No.: 01-07-30-023B with P1870 Install a control valve body with the revised TCC regulator and isolator valves. Refer to the Parts Information table below. These valves are used in all transmissions produced after January 15, 2000 (Julian Date 0015), and all of the service parts currently available through GMSPO contain revised TCC regulator and isolator valves. WE DO THIS WITH A UPDATED VALVE BODY ON EVERY 4l60e transmission
 
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#14
attachment - TSB mentioned above.....

The hard shift issue is puzzling as there was no mention....BUT full pressure when codes set has me going oops.

Gotta love TSB's - I often check them first , not this time
 

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billr

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#15
Yes the hard 1-2 shift is the first thing you will notice if the P1870 is set. The PCM has detected "something" in the trans slipping and jacks the LP up to full to reduce that slipping and chances of damage to clutches from slipping too much.

You will recall, I have a '97 Chevy van with the 4L60E that has been setting P1870 intermittently for about 10 yrs/80K miles now. At the beginning of this episode, Transman suggested trying Lube Gard "red", which I have done, and the trans is still generally OK all these years later. Yes, the Lube Gard is a "Hail Mary" play, but being suggested by Transman makes it a prayer being offered by the Pope himself as the ball is thrown...