4L60 shifts in and out of OD
03-29-2019, 03:13 PM
#1
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4L60 shifts in and out of OD As the title says my transmission shifts in and out of overdrive if I stay around 45 or so, the speed may be off a little as my speedo isn’t calibrated. Originally the trans was junkyard fresh and had a Circle D 3000-3200 stall, but the trans started slipping so I had It rebuilt and had Circle D clean and rebuild the converter. At first i thought it was in the tune and had the shop check the shift points but have had no luck. This is in a 65 C10, it has a TSP 212/218 550/550 and 1 7/8 longtubes. It makes solid power but I pretty much quit driving it. Could TCM/ECM incompatibility cause this? The ECM is on 12602802 which appears to be fo an ‘03 truck, the TCM IS PN 12590008 for an 06-07. I stripped and lengthened the harness approximately 6 1/2 feet to put the harness behind the seat so I may have done something wrong there as well. Any thoughts or ideas are appreciated.
04-03-2019, 10:20 AM
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LSX Tuning-the purple wire is connected at the brake switch, thanks for the suggestion, would it be worth the effort to check continuity on that wire? All other aspects of performance/drivability are fine.
KW Baraka-what would cause the converter to lock and unlock?
I'm in the midst of doing front brakes, shocks, etc. and will try to make an appointment with the tuner and have them log line pressure data and see of there is something there but appreciate any other suggestions on things to pursue.
KW Baraka-what would cause the converter to lock and unlock?
I'm in the midst of doing front brakes, shocks, etc. and will try to make an appointment with the tuner and have them log line pressure data and see of there is something there but appreciate any other suggestions on things to pursue.
04-05-2019, 12:12 AM
#6
Driving/cruising at the speed that's right at threshold where it wants to hook-up.
A couple MPH faster or slower and it'll lock or it won't. But if you cruise at that threshold, the TC will constantly lock and unlock; and it can feel like the tranny in alternating between D and OD.....except it'll do this faster than the tranny can up-shift and down-shift.
KW
A couple MPH faster or slower and it'll lock or it won't. But if you cruise at that threshold, the TC will constantly lock and unlock; and it can feel like the tranny in alternating between D and OD.....except it'll do this faster than the tranny can up-shift and down-shift.
KW