4l60e no lockup

bp042665

hunting nut
Joined
Nov 26, 2012
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Iva South Carolina
#16
I have rarely seen a pump cause this but it has happened about 4 times in 20+years most of the time if you put a updated VB that fixes it I have used central valve body's or what ever it takes transmission or even trans star I don't know where you live but they will ship if none are close to you
 
Joined
Jul 22, 2019
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#17
TLDR: problem was due to a leak in the pump front stator bushing due to user error during bushing replacement.

Sorry for raising the dead but I just thought i would post final solution to my issue incase it helps someone else.

Symptoms were:
- No lockup in any gear
- P1870 code with no other codes
- harsh shifting particularly in the 1-2 shift

9 times out of 10 the cause for this is a warn tcc regulator valve bore. The solution is to either ream the boar and install sonnax oversize regulator valve and sleeve, or install a spring in the bore to paralise the valve. There are pros/cons of each method which is highly detailed through a quick google search.

For me, this was not the problem. Troubleshooting steps I performed to isolate the problem:
- Monitor TCC apply variables in tech2 scan tool to ensure computer was commanding lockup. (p1870 should indicate computer is commanding lockup but you should still verify this step anyway)
- Command lockup manually using tech2
* If the computer is not commanding lockup, but will lockup when commanded, then you may have an issue such as engine misfire, overheated engine or trans. Check for other codes and resolve those first.
* If trans is not locking up when commanded, problem is either electrical or mechanical.
- Remove trans pan and command lockup with engine off ignition on using tech2. Listen to TCC apply valve in pump for the noticable click. Once activated, blow air into the solenoid to confirm its working. This will eliminate electrical issue as cause. Repeat this test with the TCC PWM solenoid in the valve body.
- Installed rebuilt valve body to eliminate leaking regulator valve as cause.
- Remove transmission and tear down pump. Problem found - The front stator was accidently damaged by me during replacement of front stator bushing during overhaul. This bushing is critical to seal. My stator was gouged out during bushing removal resulting in a leak past the bushing. This results in TCC release fluid back feeding into the torque converter lockup clutch resulting in a permanent no lockup scenario.

This took me months to identify through studying the entire tcc circuit and understanding each component and location. The problem is rare, but suggested to keep in mind when troubleshooting TCC lockup problems that are not caused by TCC regulator valve leak or 'computer not commanding'.
 
Joined
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#18
One more quick note -

If you have a no lockup condition, i strongly advise against driving the vehicle. It will cause high fluid temperatures and result in excessive wear of the 3-4 clutch pack.