Need Help with 4L60 - TC not locking?
04-04-2015, 02:05 PM
#1
Teching In
Thread Starter
Join Date: Feb 2014
Posts: 22
Likes: 0
Received 0 Likes
on
0 Posts
Need Help with 4L60 - TC not locking? I Recently rebuilt the 4L60 using "Monster in a box kit". I believe everything was done correctly. My son is reporting that the car appears to be shifting into overdrive. The engine in the car is from a 1994 and I don't know the year of the ECM/PCM or if that even matters. I do know that the Transmission pump did not say "PWM" when I rebuilt it. I have consulted that website that shows gear ratios/rpm/mph charts and I am off in overdrive. 1st, 2nd, 3rd RPM/MPH match the chart, but 4th (overdrive) is not even close. Is there a post already done that would walk me through a troubleshooting checklist? Or would my best option be to take it to a trans shop and have them tell me what's going on. Any advice would be greatly appreciated!
04-04-2015, 04:04 PM
#2
Moderator
If your MPH in 4th in much lower than expected, that is a good indication the TCC is not locking. The TCC not locking in a non-PWM is typically due to the following:
1. Codes, perhaps hidden, in the PCM - scan the PCM for codes
2. Worn valve body (I don't know if a '94 has the troublesome TCC valve.)
3. Worn out converter
Since the problem occurred after the rebuild, I would also suspect a missing o-ring on the input shaft.
A local non-chains trans shop should be able to diagnose that fairly easily by hooking up a scanner and testing the gears and lockup.
Regardless of whether you accept their remedy, please update this thread with what they said or any progress.
1. Codes, perhaps hidden, in the PCM - scan the PCM for codes
2. Worn valve body (I don't know if a '94 has the troublesome TCC valve.)
3. Worn out converter
Since the problem occurred after the rebuild, I would also suspect a missing o-ring on the input shaft.
A local non-chains trans shop should be able to diagnose that fairly easily by hooking up a scanner and testing the gears and lockup.
Regardless of whether you accept their remedy, please update this thread with what they said or any progress.
04-04-2015, 09:29 PM
#3
Like mrvedit said, if you took the input shaft o-ring off and didn't immediately replace it, it's something I think could be very easy to forget to put back on when working on a earlier year one because it's small and black. Doesn't really stand out. The new ones are colored, IIRC, and much bigger because of where they ride on the shaft.
04-05-2015, 06:54 AM
#4
Teching In
Thread Starter
Join Date: Feb 2014
Posts: 22
Likes: 0
Received 0 Likes
on
0 Posts
Mr Vedit, can you explain procedure for "scan for PCM codes"? I have a 1995 car body with a 1994 Engine and non PWM 4l60. Is "scan" something I can do at home, or do I need to take to shop?
