1991.5 mopar

I converted my a518 to lockup and got a 3 prong plug and I'm not sure how to wire it. I heard the closest one toward the engine is overdrive, middle is power and the rear is lockup. I previously had overdrive on a toggle switch on the dash. Help would be much appreciated

patdaly

See below,

pin 1 Brown OD engage ( drag to ground )

pin 2, Lt Green/Blk 12V fused ( applied when engine is on )

pin 3 Red/Black TC Lock ( drag to ground )

1991.5 mopar

So I run a line from the battery to the middle wire, the front wire to a switch for overdrive and ground it and another wire to a switch and ground it?

Angry Johnny

The middle wire is ignition hot, not battery. The two outers are O/D and lockup, they get grounded to engage. So it really doesn't matter which is which as you are going to be putting two switches in it. I'll see if I can find which one is which though.

1991.5 mopar

Do I need to run power for the switches and ground them with the O/D and lockup wires?

patdaly

No power to the switches, you use the switches to ground the circuit. You apply the 12 volts switched edit, I think this is where you are confused, the switch we refer to is the ignition key switch! ( only on when key is on ) to the center, the 12volts can't do anything till you complete the ground side with the switch.

Also, was your truck the 3 speed 727 non-OD or was it OD already and you added TC LU?

If so, then you can use the original OD signal and just add the TCLU.

1991.5 mopar

It was a 46rh and I had it rebuilt and converted to have a lockup up converter by a different front pump, valve body, input shaft, etc. it was previously a 2 prong plug now it's 3 prong cause of lockup and I got a a new plug from the junkyard and it has the 3 colored wires. If I'm not mistaken are you saying I only run one wire to each switch?

1991.5 mopar

Do you know of anyone that would have a schematic ?

Angry Johnny

It is so very simple. Center wire is key on 12 volts. Outboard wires each go to a separate, simple on/off toggle switch then from the toggle switches to a good ground, preferably at the battery or on the engine.

You can connect the two ground wires off the toggles together and just run a single wire out to a ground.

1991.5 mopar

Where does the middle 12 volt wire go to? Thanks Johnny!

patdaly

That's even easier.

If I read my 91 manual right, your current 2 pin connector should have a dark blue wire for 12Volts, and a Orange/Light green wire that makes your old OD work. To verify, see if you have 12Volts at the DB wire with the key on.

If so, simply snip off the 2 wire connector, hook the dark blue from the old setup to the Lt green/Black from your 3 wire connector ( should be the middle pin ) and the orange/light green wire from your old setup to the brown wire on the 3 pin connector. Then hook up the red/black wire from the 3 pin connector to a switch, with the other terminal on the switch to ground.

This will let your truck control overdrive just exactly like it used to, and you have manual control over the TC LU. Later you can get fancy and hook up a adjustable pressure switch to your trans and dial in TCLU with no manual switch........

1991.5 mopar

That sounds like a good idea, I'm more concerned on getting overdrive hooked up. Will lockup disengage when I turn off overdrive from the switch? Thanks for taking the time to figure it out for me!

1991.5 mopar

Also the truck is starting in 2nd gear since the O/D unit isn't wired, so it would be nice not having to shift manually

patdaly

Whoa, I don't believe that is correct. OD should have nothing to do with gears 1 thru 3 as that part is pure mechanical 727..............

Are you sure you have all your linkages hooked up correctly and adjusted correctly?

Angryjohhny, am I correct about this?

1991.5 mopar

That's what the trans shop told me that built it and yes all linkages are correct and shifts into all gears correctly