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post #1 of (permalink) Old 01-31-2004, 04:34 PM Thread Starter
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th400 shift issues

the th400 in my truck won't upshift until almost redline. this is not all the time though, it is periodically. One day in three it will shift nearly perfectly, but most days it won't shift until i have the engine revved all to hell. I just replaced the vacuum modulator, but it is still doing the same thing. i pulled the governor out and the gear on it is not worn at all. i will adjust the modulator down some next, but i doubt this is it. any thoughts?
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post #2 of (permalink) Old 02-02-2004, 04:31 PM
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Re: th400 shift issues

Check the kickdown switch on the transmission. I had this problem and thought the trany was bad but it was just that the wires for the kickdown had gotten burned and were shorting out. Just unplug the harness from the trany and drive it. If it shifts okay check the wires for bad insulation.
post #3 of (permalink) Old 02-03-2004, 03:41 PM Thread Starter
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Re: th400 shift issues

never had the kickdown witch since i have owned it. never had this problem in the past 5 years either, so it isn't that.
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post #4 of (permalink) Old 02-26-2004, 01:06 AM
 
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Re: th400 shift issues

drop the pan, my experience with this type of problem is the filter drops down on the 400, and will give you the same symptoms your expericing. bought a truck doin same thing as your for 150.00 4x4 even all i had to do was service the trans cuz the filter dropped down...... sold it 2 weeks later for 2 grand profit
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post #5 of (permalink) Old 02-29-2004, 09:11 PM Thread Starter
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Re: th400 shift issues

guess i'll try this next. thanks
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