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Transmission shifts in & out of overdrive
- Thread starter wlrdlr49
- Start date
Detroit Dan
New Member
could be the TCC solenoid going bad. It's a solenoid switch in the pan, well actually on the valve body, not real hard to change and about $40 iirc. Without getting too in-depth there are a lot of other things that could play a part in it, but that's the easiest thing to change and should do it before you get too deep into it.
I had a similar problem I chased for months. Tranny shop told me 4th was gone but I didn't believe them, because it was working some of the time. I figured a mechanical failure means something broke and it stays broke. I had to change my TCC solenoid and both my shift solenoids, also tried new vssb speed sensors, finally I broke down and did the Surecure on my valve body. I don't know how many miles you have, but you might have the problem I had. There is a rod behind the TCC solenoid that goes into the valvebody and it has fluid on the other side of it. Electrical signal moves it in and out, pinholes in the rod allow hydraulic flow through, engaging or disengaging lockup. What happens is that rod moving back and forth in it's aluminum bore a couple zillion times eventually wears the hole out of round, then there is a hydraulic leakdown past the rod.
The fix for this is to pull the valve body down, pull out the rod and ream the hole out a little bigger then sleeve it with a properly sized steel sleeve. Then put it all back together, no more leakdown. It fixed mine. I only did it as a last resort, after replacing all the solenoids and senders first, trying to fix it on the cheap. After buying the solenoids, senders, about 6 fluid changes and then the kit, I think I repaired my tranny for under $400 total, and obviously all those parts weren't necessary, but at least one of the shift solenoids was bad. Anyway, the valvebody R&R isn't as bad as it sounds, I took pictures first so I wouldn't muff it up, then just tried to be real careful and follow the directions for the first time in my life. It's only about an hour job.
Mine was working fine cold, but then coming out of lockup at the exact same place everyday on my way to work, I figured out it was a temperature thing- once the fluid got to a certain temp it was thin enough to leak around the rod.
Look for Sonnax Surecure on the net, if you can't find it I'll see if I can locate a link for you. And if you decide to try it let me know, I've got the tool you have to buy to install the kit, I'll let you have for the cost of shipping, I'll never need it again.
I had a similar problem I chased for months. Tranny shop told me 4th was gone but I didn't believe them, because it was working some of the time. I figured a mechanical failure means something broke and it stays broke. I had to change my TCC solenoid and both my shift solenoids, also tried new vssb speed sensors, finally I broke down and did the Surecure on my valve body. I don't know how many miles you have, but you might have the problem I had. There is a rod behind the TCC solenoid that goes into the valvebody and it has fluid on the other side of it. Electrical signal moves it in and out, pinholes in the rod allow hydraulic flow through, engaging or disengaging lockup. What happens is that rod moving back and forth in it's aluminum bore a couple zillion times eventually wears the hole out of round, then there is a hydraulic leakdown past the rod.
The fix for this is to pull the valve body down, pull out the rod and ream the hole out a little bigger then sleeve it with a properly sized steel sleeve. Then put it all back together, no more leakdown. It fixed mine. I only did it as a last resort, after replacing all the solenoids and senders first, trying to fix it on the cheap. After buying the solenoids, senders, about 6 fluid changes and then the kit, I think I repaired my tranny for under $400 total, and obviously all those parts weren't necessary, but at least one of the shift solenoids was bad. Anyway, the valvebody R&R isn't as bad as it sounds, I took pictures first so I wouldn't muff it up, then just tried to be real careful and follow the directions for the first time in my life. It's only about an hour job.
Mine was working fine cold, but then coming out of lockup at the exact same place everyday on my way to work, I figured out it was a temperature thing- once the fluid got to a certain temp it was thin enough to leak around the rod.
Look for Sonnax Surecure on the net, if you can't find it I'll see if I can locate a link for you. And if you decide to try it let me know, I've got the tool you have to buy to install the kit, I'll let you have for the cost of shipping, I'll never need it again.
Also, check your brake light switch. If it loose or rattling it can tell the TC to disengage. Has the cruise control ever kicked off on you?