TC lockup Mod.

[ManicMike]

wouldnt it be just easier to just buy this and install it? i was thinking about getting on! http://www.summitracing.com/parts/BDD-1030395/

$308 is A LOT of money for something that can be built for under $10.

 

[Kevin 007]

X2.
Any thoughts on that relay?

 

[trackspeeder]

Good to know! One question tho, why is there no pressure in 2nd gear? The engine (and therefore the converter) is still turning at decent speed provided one don't let her idle down, and pump is driven off the converter, right?

It's not that there is no pressure. The tranny has pressure but not enough to hold the converter, second gear and the coast clutch in one shot. Plus it still needs to lube the rear of the tranny. Thats alot or the pump to do. Specially if its the early E pump pre 95 unit.

 

[Kevin 007]

Just went and pulled a bunch of relays from a wrecking yard to see if I could find one with poles 85 and 86 in the same positions as the diagram...to no avail.

Ive got mine all wired up as the diagram suggests, but im scared to try it out until I find out about this

 

[Kevin 007]

But on the diagram, it shows power to pole #85 via 12v "key-on" from fuse box. This would power have power anytime the truck is running and not just when brakes are applied. So by the way you described it in this post, seems like the TC stay unlocked all the time. So I don't know if I should follow the diagram or your description.
Sorry about the stupid questions, just trying to make this relay work on my rig to.

Lol, I see you're living up to your username The relay is a piece of cake - first you gotta have the right relay tho, you need one with 5 terminals, which you should be able to buy at about any place that sells electronic components. You need the 5-pole relay because it's actually switching the current flow between terminals #87a (powered when relay is disengaged) and #87 (powered when the relay is engaged), if you leave terminal #87 open you end up with an interrupting relay. Right now you probably have the wire from the TC to the switch directly, to install the relay you cut that wire at a suitable location and add two spade connectors to the now-loose ends and you plug them onto terminals #30 and #87a on the relay, it shouldn't matter which end goes on which terminal but just as a good measure plug the end from the TC onto #30 and the end to the switch on #87a. Leave terminal #87 open, nothing connects to it for this job. Then run a wire from your brake switch on the pedal (one side is always hot on that, you want the other side, else your converter will never lock), add a spade connector at the end of the wire, and plug that onto terminal #85 on the relay. Then ground terminal #86 on the relay with another wire with a spade connector, there are several grounds bolted next to the fuse panel so you can use that location if you want to, or alternatively the steering column's aluminum brace is a great ground too. So now what happens is the current from the TC enters the relay from terminal #30 and exits it from #87a (those two are normally-closed when there's no trigger signal to the relay), this is your slave circuit. Then when you step on the brakes a tiny amount of current flows from the BOO switch in the relay through terminal #85 and into ground through terminal #86, this is your master circuit that energizes the relay to switch the slave circuit's exit point from terminal #87a to #87, but we left #87 empty so essentially it switches current from the TC into nothing and thus interrupts current flow and results in converter unlocking regardless of what position your big red manual switch is in. Then when you let off the brakes the relay's master circuits powers off, the slave circuit switches exit points from #87 back to #87a, and restores continuity from the TC to your big red manual switch.