4L60E High Line Pressure
4L60E High Line Pressure I picked up a used 4L60E (96 model), rebuilt it and modded it for my 89 IROC. I have upgraded to a 2001 PCM and using EFI connections 24x system and wiring harness to make it all work. Transmission line pressure at idle is 150 psi in park, neutral, drive, D3, D2, and D1. Reverse is 200 psi. Had a transmission man with a Tech 2 try to tie in and force different current levels to the pressure control solenoid (epc) to see if that changed the line pressure, but for some reason beyond my comprehension it wouldn't allow him to do this. So, I'm wondering if anyone has had this type of experience where the line pressure at idle is about twice as high as it should be and if you have, what did you have to do to fix it.
PCS valve needs to be energized to blow off pressure;
maybe you have a harness open circuit?
Scan tool should be able to report both PCS duty and
PCS current; if current reads zero then there's your
pony.
maybe you have a harness open circuit?
Scan tool should be able to report both PCS duty and
PCS current; if current reads zero then there's your
pony.
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From: Ann Arbor, MI
About 1 amp of current should bring the EPC down to idle pressure; a good scanner will read the EPC current as reported by the PCM. If it reads 1 amp and the pressure is still high, I would next replace the EPC and/or check that the boost valve was assembled correctly.
IIRC some very early 4L60E (1994 ??) had a pump that used a shorter boost valve; if you used a later model boost valve, you would also have high pressure.
First, someone would need to confirm this.
Second, if you have a '96 it probably does not apply.
IIRC some very early 4L60E (1994 ??) had a pump that used a shorter boost valve; if you used a later model boost valve, you would also have high pressure.
First, someone would need to confirm this.
Second, if you have a '96 it probably does not apply.
High Line Pressure I am able to read PCS valve resistance from PCM red connector pins 6 and 8 and I read 5 ohms. To me that says harness is good and PCS valve is good. Am I wrong here? I have ordered a new PCS valve and will put that in when I get it. I'm going to pull the regulator and boost valves out to make sure I didn't mess something up there. Like I said in my original post, I'm not sure why the scan tool wasn't able to work. I may have to go back there and try that again.
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From: Ann Arbor, MI
That is a good way to test the harness and PCS valve; 5 ohms is correct. However, the PCS could still be sticking. I know that might be rare, but so is having such a high line pressure; the previous builder might have turned to PCS shaft to force higher pressure. It would still be useful to know how much current is running through it.
High Line Pressure That is a good way to test the harness and PCS valve; 5 ohms is correct. However, the PCS could still be sticking. I know that might be rare, but so is having such a high line pressure; the previous builder might have turned to PCS shaft to force higher pressure. It would still be useful to know how much current is running through it.
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4L60E problem i rebuild my 4l60e 2wd transmission i I did everything right but now I can't moving my truck I don't know why I Check the transmission fluid pression is 0 look like is not circulate Is not come to coil do anybody have any idea what I did wrong
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Verdad Gallardo Moderator
Joined: Aug 2010
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From: Ann Arbor, MI
The most likely cause of this is incorrect installation of the torque converter. Did you measure the distance from the converter mounting pads to a long straight edge placed across the bell housing? That distance needs to be 1-1/8" (+/- 1/8").
Also what was the gap between the mounting pads and the flexplate.
