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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 73SWBBB on September 16, 2011, 04:08:25 pm

Title: TH400 trans brake switch?
Post by: 73SWBBB on September 16, 2011, 04:08:25 pm
I am learning a lot right now but am unable to figure out what I've got going on with the one wire. It is connected to my brake peddle and runs straight down to a single prong connector on the driver side of my transmission. All i want to know is.... what is it? I can't seem to get a straight answer from my research.

Im not a total nub here I am just trying to figure out why someone would have done this. It seems like it gives it some sort of launch capability? Can I get rid of it?
Title: Re: TH400 trans brake switch?
Post by: HAULIN IT on September 16, 2011, 08:06:34 pm
Something doesn't sound right here...On the brake pedal would be the brake light switch. It would be positioned so when you move the pedal, the switch would "close". It is located on the bracket that the pedal swings from & is kinda round, tube looking thing with a push button on the end.
The TH400 kick down switch mounts to the side of the bracket mentioned above & the throttle pedal hits it & slides to full throttle. It looks like this:
http://www.americanclassic.com/Google_Base_HTML_Pages/EL870NOS-1973.htm
It should have a 12v wire from the fusebox to one of the blade terminals & the other terminal should have a wire going to the side of the transmission that you mentioned.
Either you have traced the wires wrong were it goes from the pedal bracket or someone has it all fouled up. Do your brake lights work? Hope this helps! Lorne
Title: Re: TH400 trans brake switch?
Post by: Blazin on September 16, 2011, 08:31:03 pm
Also does it kick down into 2nd when you step on it good?
Title: Re: TH400 trans brake switch?
Post by: 73SWBBB on September 16, 2011, 11:25:43 pm
You are correct sir, I totally biffed my thoughts as I wrote that I was going from memory at work. Got home and saw that wire going straight to the gas pedal attached to the exact switch you provided a pic of. Also, it does not do anything when I step on it good. I blew it up a few months ago and only owned it for about a month before I did that. So i dont even know the truck very well other than the fact that I have way to much money into it and I'm not going to stop until its back on the road cleaner than ever by my own hands. Thanks for the help on that though, this is the most in depth build I've ever gotten myself into.
Title: Re: TH400 trans brake switch?
Post by: HAULIN IT on September 16, 2011, 11:34:13 pm
Good Deal! Checking the switch to see if it is working is fairly simple. Pull the connector off of the transmission , put a normal test light in the plug (ground the wire lead on the light) & floor the gas pedal, the switch slides all the way...the light should light up :D Check & report. Lorne