How to wire in a toggle switch for lock up

I got a trans for my 85 Ramcharger today. Its a 904 out of a van but it has an electronic lock up and mine did not. Ive been told i can wire in a toggle switch to lock the torque converter. Is this true? Easy job? Can it hurt anything? How would i go about doing it? Please help moparts!!!!!

bump. Find it hard to believe no one wants to help me out with this

less than 2 hours on a sunday. give em a few before you git yer panties in a bunch....

Is it an over drive trans also?

electronic lock up and over drive in a A500 trans Yes

But can't think of just electronic lock up

Its prolly a A998 trans, those used automatic lockups and cannot be 'wired for on/off'.

Not an overdrive. it has a plug in for a lockup at the back of the trans.

I haven't done a lockup 904, but I have done a few other lockup convertor retrofits. Basically all you need to do is determine the wire that's the 12V source that locks up the convertor.

Personally I normally wire mine thru a relay and cruise control switch on the brake pedal. I activate it thru a momentary on/off pushbutton switch on the dash. That way it deactivates when the brake pedal is pushed.

Never seen a 904 w/ electronic lockup. Interesting...

IIRC it's a hydraulic apply with electric release?

Yep, all 3-speeds had hydraulic lockup but some 904's from the mid eighties-on had electic release.

So will it cause any damage to the trans if I do not hook it up?

I would imagine it wouldn't unlock the converter and the 904 will go into meltdown.

I dont understand.

So i have to tackle this so I can use the Ramcharger as mywinter beater. Will this cause damage to this 904? I need this truck to be a dependable driver.

Leaving it unlocked will not hurt the trans, you can go the super simple route by running 12 volt to that plug via a toggle switch. Not the best method but certainly functional enough for a beater if you care to use the lockup option.

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So will it cause any damage to the trans if I do not hook it up?

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It shouldn't, but not having lock-up will cost you fuel mileage in top gear.

It's worth your time to go by the very good wiring diagram above and get it to work.