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#1 |
Registered User
Join Date: Oct 2003
Location: San Jose Ca.
Posts: 3,335
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400 Tranny Kickdown
Ok this is weird. I put the truck in shop for a kickdown issue. With a carb mounted kickdown switch and a factory kickdown harness the tranny would kick down to passing gear but it would not shift back to 3rd from 2nd. The tranny guy is stumped. According to the assembly manual the orange wire goes to the tranny from the front spafe of the switch. The pink wire goes to the fuse box. Now for the weird part. If you unplug the power (pink wire) it will kick down and let go no problem. If you plug in the power it will hang in 2nd. Any thoughts? Tranny was rebuilt and they have gone through everything.
Thanks
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RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234 |
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#2 |
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Join Date: Jun 2004
Location: Beeville, Texas
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Maybe the kickdown switch is bad?
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#3 |
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Location: Seattle, WA, USA
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...that's why earlier when you posted about this I told you to test the switch with a 12v probe tester. You have to isolate the switch as a problem before you can determine that the detent solenoid inside the transmission is bad.
Go back to your original thread and try what I suggested. If it turns out your switch is bad you'll at least know it's not the transmission, and you won't be forced to waste any more time.
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#4 |
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Join Date: Nov 2004
Location: New Lenox,IL
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That was happening to me for a while then I just unpluged all of it and manually downshift into passing gear and back up to 3rd, that worked for me.
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1985 Chevrolet C-30 454 1-TON Dooley 1969 CHEVROLET CST-10 PICK-UP Good memories 1999 Chevrolet Z71 Ext. cab 5.7L Good Memories With a quart of oil, and a gallon of gas, she won't let no other car pass!!!. ![]() ![]() |
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#5 |
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Join Date: Oct 2003
Location: San Jose Ca.
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Cobalt. I forgot to update the thread. That was done and both switches checked out fine. I took it home last night and get this. If you unhook the kickdown switch it will kickdown at half WOT. Yes with no kickdown setup installed it will kickdown and go back into 3rd when you let off of it. Tranny shop is building a new one for me and it will be ready on tuesday at no charge. I figure while they are doing that I can put a new flexplate on there and maybe that will get rid of the vibration I was having.
Thanks for the help guys.
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RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234 |
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#6 |
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Join Date: Jun 2002
Location: central pa
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One quick question is are you sure you have good full manifold vacuum 12" or better? The modulator could be keeping it in 2nd because it thinks you need the power.
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#7 | |
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Join Date: Oct 2003
Location: San Jose Ca.
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Quote:
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RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234 Last edited by skokie; 02-19-2005 at 06:41 PM. |
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#8 |
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Location: Seattle, WA, USA
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What do you mean "half WOT"? If you don't have power to the detent solenoid it shouldn't kick down at all.
So, you have full manifold vacuum, and there's no fluid in the modulator? It's working? If the modulator collapses I could understand why it would help to hang up the valve body. Are you getting transmission fluid in your manifold? When they did the rebuild was a shift kit installed?
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'69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA. |
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#9 |
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Join Date: Oct 2003
Location: San Jose Ca.
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Yep at half or 2/3rd WOT it kicks down into passing gear. I verified this by disconnecting the the entire kickdown setup. I was like what!!!! There was a shift kit put into the tranny when they rebuilt it. Which manifold are you asking about?
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RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234 |
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#10 |
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Your intake manifold. If the modulator is busted fluid can be sucked from the transmission through the busted diaphram in the modulator up into the intake manifold. Since the intake manifold provides full vacuum it wouldn't take long for transmission fluid to end up in your intake.
Shift kits can be funny. If they're not done right you can have ALL KINDS of grief with your valve body. I'd be questioning the hell out of the shop about how they installed the shift kit and whether or not they made any modifications to the new valve body and circuit for your transmission (drilling holes in specific places, or using different size ball bearings...that kind of thing...
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'69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA. |
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#11 |
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Join Date: Oct 2003
Location: San Jose Ca.
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No tranny fluid in the intake manifold. As far as the shift kit goes I said forget it on the new build just get me a correctly working tranny. Shift kit can go in later. I want to get this sucker on the ROAD!!!!!
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RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234 |
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#12 |
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Join Date: Oct 2003
Location: San Jose Ca.
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Ok tranny guy called. He has put a new tranny in. He did not hook up the kickdown setup. He wants to wait for me to get there in order to do it. Replacement tranny is a total replacement. Only things he used from the old tranny was the drive and driven gear. I will let everyone know what happens.
Thanks for all the help.
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RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234 |
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