Transmission won't shift
12-23-2014, 10:20 PM
#1
Transmission won't shift 4l60e, had problem with trans slipping after about 3 or 4 miles of driving, was recommended to change pressure solenoid, removed pan and changed solenoid, after putting back together trans would not shift out of first. learned later that slipping problem was more likely he torque converter, removed trans (had it looked over while out) and replaced converter...after reinstalling trans will not shift. Checked pressures and power to trans...all good. Had someone with scanner to look, not codes, trans would shift when commanded through scanner (also checked the solenoids for operation, all ok). Cold not see TPS movement on scanner so changed sensor, still no movement on scanner, cheeked wiring for continuity, all good...checked for ref voltage, 5v there and ground good...used volt meter to look for tp sense voltage and could see voltage rise when throttle moved.
I'm lost now...PCM is sending and receiving proper signal, but it's not readable on the scanner and I'm thinking it's the reason the trans will not shift.
Long story to give the whole story...need help with what to ck next.
Thanks
I'm lost now...PCM is sending and receiving proper signal, but it's not readable on the scanner and I'm thinking it's the reason the trans will not shift.
Long story to give the whole story...need help with what to ck next.
Thanks
12-24-2014, 10:08 AM
#2
Moderator
Assuming I have the right person, about half way through those problems, the OP started to communicate with me by email. The OP was checking everything and had a pressure gauge on it. However, he could not locate a scanner that showed/commanded gears.
Something I just thought of now - you should check/replace the pressure manifold switch. If this is bad, the PCM does not know what position the shifter is in and might be reading it as D1. When you replaced the PCS, you may have bumped it or its wiring. (There aren't that delicate, but after 15 years might have been on its last thread.)
Beyond that, you really need to locate a good scanner. (IIRC he is too far from any trans shop.)
Something I just thought of now - you should check/replace the pressure manifold switch. If this is bad, the PCM does not know what position the shifter is in and might be reading it as D1. When you replaced the PCS, you may have bumped it or its wiring. (There aren't that delicate, but after 15 years might have been on its last thread.)
Beyond that, you really need to locate a good scanner. (IIRC he is too far from any trans shop.)
12-24-2014, 12:09 PM
#3
Assuming I have the right person, about half way through those problems, the OP started to communicate with me by email. The OP was checking everything and had a pressure gauge on it. However, he could not locate a scanner that showed/commanded gears.
Something I just thought of now - you should check/replace the pressure manifold switch. If this is bad, the PCM does not know what position the shifter is in and might be reading it as D1. When you replaced the PCS, you may have bumped it or its wiring. (There aren't that delicate, but after 15 years might have been on its last thread.)
Beyond that, you really need to locate a good scanner. (IIRC he is too far from any trans shop.)
Something I just thought of now - you should check/replace the pressure manifold switch. If this is bad, the PCM does not know what position the shifter is in and might be reading it as D1. When you replaced the PCS, you may have bumped it or its wiring. (There aren't that delicate, but after 15 years might have been on its last thread.)
Beyond that, you really need to locate a good scanner. (IIRC he is too far from any trans shop.)
We could not see TPS and that led me to do wiring and power checks on the circuit for it...all checked good and I even used a voltmeter to see the output from the senor at the computer (red conn pin 24 ~0.4 - 4.5v) but I'm not seeing that TPS movement on the scanner. It's my understanding that TPS is one of those essential parameters necessary for trans.
Really stumped by not being able to see the TPS on scanner, knowing that the signal is getting to it...I have also swapped in a working PCM, with no change????
12-24-2014, 02:24 PM
#4
Moderator
Even with a TPS of 0% the trans should shift when the speed is high enough.
Since the shifting worked before you changed the PCS, I suspect you accidentally "broke" something and the pressure switch manifold is a reasonably suspect.
Some of the strangest and most stubborn problems reported on this forum turned out to be due to a bad pressure switch.
Since the shifting worked before you changed the PCS, I suspect you accidentally "broke" something and the pressure switch manifold is a reasonably suspect.
Some of the strangest and most stubborn problems reported on this forum turned out to be due to a bad pressure switch.
12-29-2014, 10:53 PM
#5
Even with a TPS of 0% the trans should shift when the speed is high enough.
Since the shifting worked before you changed the PCS, I suspect you accidentally "broke" something and the pressure switch manifold is a reasonably suspect.
Some of the strangest and most stubborn problems reported on this forum turned out to be due to a bad pressure switch.
Since the shifting worked before you changed the PCS, I suspect you accidentally "broke" something and the pressure switch manifold is a reasonably suspect.
Some of the strangest and most stubborn problems reported on this forum turned out to be due to a bad pressure switch.
Happy New Year!
01-08-2015, 10:49 PM
#6
Have now replaced the pressure manifold, and internal wiring harness...and still will not shift out of first. Pretty sure it's now a communication problem between the PCM and Transmission. Need help now in determining which or pin in connectors to check...got to figure this out HELP!
01-09-2015, 08:56 AM
#7
Moderator
Wow, your trans problem is really a stubborn one.
Did you ever find a scanner with which to command different gears and read what position the shifter is in?
In post #4 I have the pinout to a '99-'02 PCM which also matches many later years. (But '98 is very different)
https://ls1tech.com/forums/automatic...lems-help.html
And here is another electrical diagram:
http://www.msgpio.com/manuals/mshift/wiring.html
Good luck with these, but if not already, I think you need to find a good scanner.
Did you ever find a scanner with which to command different gears and read what position the shifter is in?
In post #4 I have the pinout to a '99-'02 PCM which also matches many later years. (But '98 is very different)
https://ls1tech.com/forums/automatic...lems-help.html
And here is another electrical diagram:
http://www.msgpio.com/manuals/mshift/wiring.html
Good luck with these, but if not already, I think you need to find a good scanner.
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01-09-2015, 12:14 PM
#8
Wow, your trans problem is really a stubborn one.
Did you ever find a scanner with which to command different gears and read what position the shifter is in?
In post #4 I have the pinout to a '99-'02 PCM which also matches many later years. (But '98 is very different)
https://ls1tech.com/forums/automatic...lems-help.html
And here is another electrical diagram:
http://www.msgpio.com/manuals/mshift/wiring.html
Good luck with these, but if not already, I think you need to find a good scanner.
Did you ever find a scanner with which to command different gears and read what position the shifter is in?
In post #4 I have the pinout to a '99-'02 PCM which also matches many later years. (But '98 is very different)
https://ls1tech.com/forums/automatic...lems-help.html
And here is another electrical diagram:
http://www.msgpio.com/manuals/mshift/wiring.html
Good luck with these, but if not already, I think you need to find a good scanner.
Having the scanner cause the trans to shift tells me the electrical connections should be good (I think), and that maybe some logic is not responding (again I think)...but that's where I am now. Oh and transmission is a 95 4L60E and the PCM is from a 99 (checked in the beginning to be sure the connector on trans had the correct number of pins)
Last edited by deelli; 01-09-2015 at 12:15 PM. Reason: trans year
01-09-2015, 08:10 PM
#9
Moderator
Strange that the scanner was not reading TPS and VSS. You told me that your speedometer works, which indicates the VSS is working.
Therefore this scanner may not be compatible with your car either.
However, if the scanner is correctly reading the shifter position, but shows no change when you move the shifter, that is a huge clue. I would triple check the wiring on pins N, R and P.
The way I read the schematic on the msgpio.com page, if Pin N were already grounded (e.g. shorted to ground), the PCM would think the shifter is in D1 and would not command any shifts.
So, if there is any way you can do so, put a volt meter on Pin N and turn on the ignition. With the Shifter in D1 or R, it should read 0V, but in D2, D3 and D4 it should read +12V.
Therefore this scanner may not be compatible with your car either.
However, if the scanner is correctly reading the shifter position, but shows no change when you move the shifter, that is a huge clue. I would triple check the wiring on pins N, R and P.
The way I read the schematic on the msgpio.com page, if Pin N were already grounded (e.g. shorted to ground), the PCM would think the shifter is in D1 and would not command any shifts.
So, if there is any way you can do so, put a volt meter on Pin N and turn on the ignition. With the Shifter in D1 or R, it should read 0V, but in D2, D3 and D4 it should read +12V.
01-09-2015, 08:16 PM
#10
Moderator
While not related to your immediate problem, your '95 trans is not fully compatible with a '99 PCM. In particular, a '95 uses a PWM 3-2 downshift solenoid while the PCM assumes an on/off solenoid. Not sure what the symptoms would be.
01-09-2015, 09:29 PM
#11
Strange that the scanner was not reading TPS and VSS. You told me that your speedometer works, which indicates the VSS is working.
Therefore this scanner may not be compatible with your car either.
However, if the scanner is correctly reading the shifter position, but shows no change when you move the shifter, that is a huge clue. I would triple check the wiring on pins N, R and P.
The way I read the schematic on the msgpio.com page, if Pin N were already grounded (e.g. shorted to ground), the PCM would think the shifter is in D1 and would not command any shifts.
So, if there is any way you can do so, put a volt meter on Pin N and turn on the ignition. With the Shifter in D1 or R, it should read 0V, but in D2, D3 and D4 it should read +12V.
Therefore this scanner may not be compatible with your car either.
However, if the scanner is correctly reading the shifter position, but shows no change when you move the shifter, that is a huge clue. I would triple check the wiring on pins N, R and P.
The way I read the schematic on the msgpio.com page, if Pin N were already grounded (e.g. shorted to ground), the PCM would think the shifter is in D1 and would not command any shifts.
So, if there is any way you can do so, put a volt meter on Pin N and turn on the ignition. With the Shifter in D1 or R, it should read 0V, but in D2, D3 and D4 it should read +12V.
01-09-2015, 11:12 PM
#12
Moderator
Yes. I realize that is difficult in many cars because your best best might be to access the wiring at the PCM connector. I just don't have any other ideas right now. (Trivial in my car because I keep the PCM and wiring easily accessible for my own experimentation.)