4+3 Overdrive "Problems"
Thread Starter
4th Gear
Joined: Mar 2006
Posts: 4
Likes: 0
4+3 Overdrive "Problems"
I have an 85 Vette, bone stock. Its got 123k on it.
My overdrive sometimes kicks on and off, or doesn't come on at all. Its pretty much random and seems like it has a mind of its own some days.
The "Overdrive Engaged" light comes on and off with the unit, so I think it might be a bad switch or relay and not a problem with the unit itself. Any ideas? I think I just need help figuring out where exactly to start on fixing this "bug" I'm having.
Thanks guys.
The car is also for sale, but I would really like to fix this myself before selling her, so nobody else has to deal with this later.
My overdrive sometimes kicks on and off, or doesn't come on at all. Its pretty much random and seems like it has a mind of its own some days.
The "Overdrive Engaged" light comes on and off with the unit, so I think it might be a bad switch or relay and not a problem with the unit itself. Any ideas? I think I just need help figuring out where exactly to start on fixing this "bug" I'm having.
Thanks guys.
The car is also for sale, but I would really like to fix this myself before selling her, so nobody else has to deal with this later.
Racer
Joined: Sep 2005
Posts: 304
Likes: 1
From: Carson City Nevada
On my 87, the wires at the relay were missing all of the coating. The relay on mine is on the firewall right above the drivers side valve cover. All of the wires shorted together intermitantly and it shifted in and out of OD randomly. The light came on with it also. You might want to take a look. Good luck.
Intermediate
Joined: Jul 2007
Posts: 34
Likes: 0
I got sick of playing the 4+3 game years ago so I wired a toggle switch to the wires on the side of the auto unit to my dashboard. Now when I want the damm thing on I flick the switch (which is only when im on the interstate) walla I solved the problem for under 10 bucks. GM produced this damm thing to meet federal fuel standards not for performance.
Racer
Joined: Mar 2004
Posts: 252
Likes: 1
From: Troy Illinois
I had a simmilar problem with my 1985 and changed the relay (front relay next to the wiper motor). The plug was full of gunk so I cleaned it real well with an electrical contact cleaner and have had no trouble since.
Burning Brakes
Joined: Sep 2006
Posts: 1,202
Likes: 3
From: MD
Yeah, I got sick of mine doing the same thing so I hardwired it (then I removed the 4+3 and went to a T5). On mine it turned out to be the plug shorting out from the insulation pulling back. Clean up the plug and it should be ok.
Burning Brakes
Joined: Sep 2006
Posts: 1,202
Likes: 3
From: MD
Do a search, there's a good long thread on the T5 and the other trans'. Anesthes has a whole webpage dedicated to it, and I think 2 or 3 guys have done it now. It wasn't that hard, but if you feel weird cutting on your vette (a lot) then it's not for you. You have to cut out the shifter tunnel, a lot of the dash console, etc. It's straightforward, but there's no going back and it's not even close to OEM. If I had the money I'd do the Keisler TKO kit, but it was like $500 to do the T5 and it's $3800 to do the Keisler which still requires some cutting.
Drifting
Joined: Dec 2003
Posts: 1,492
Likes: 94
From: Westfield MA
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