Best Way to Control Converter Lockup on 1989 999

[Professor Fate]

It is sounding to me like the electrical connection.doesn't apply the lock up, It simply locks out the lock up & lock up is still hydraulically controlled...

That's how mine worked. It was out of an '89 half ton, by that time they had changed the designation to 32RH.

 

[1WildRT]

Well that's lame...

 

[Ceedawg]

Thanks everyone for the input. I have both a 78 and 79 lu 999 and a 89 lu I'm sure 999, out of a full size Dodge 1/2 ton van with a 318. I'm assuming this would have the low gear set in it? I'm sure the 89 would be the better one to rebuild.

78-79 would be the best imo

 

[340inabbody]

So I am not the only one @lemondana

Post in thread 'Manually Controlled Lock Up 904'

Feb 17, 2026

I use a manual switch for both the overdrive and the lock-up in my 904 based A500 (RH42) trans. It's worked just fine for about 16,000 miles so far. You just have to remember to hit the switch when you roll off the interstate up to a stop sign. After a few thousand miles I pretty much started hitting the buttons without really thinking about it.

• str12-340

trying to do this right now. My LU trans is a 904 from 1987. Single wire. Has the steel low gears and I assume part throttle kickdown?

So if that single line went to an ecu for “tow” wouldn’t that be 12V positive to lock and to prevent stall? Just thinking out loud.

 

[Ceedawg]

So I am not the only one @lemondana

Post in thread 'Manually Controlled Lock Up 904'

Feb 17, 2026

I use a manual switch for both the overdrive and the lock-up in my 904 based A500 (RH42) trans. It's worked just fine for about 16,000 miles so far. You just have to remember to hit the switch when you roll off the interstate up to a stop sign. After a few thousand miles I pretty much started hitting the buttons without really thinking about it.

• str12-340

trying to do this right now. My LU trans is a 904 from 1987. Single wire. Has the steel low gears and I assume part throttle kickdown?

So if that single line went to an ecu for “tow” wouldn’t that be 12V positive to lock and to prevent stall? Just thinking out loud.

It’s a one wire thing, 12 volt switch. On a side note my former truck, 92 diesel auto kept burning up the OD switch at the throttle. I put a switch on the shift level to do it manually, after about a month driving it this way it became second nature to flip that switch, not much different than a manual trans in a way. For the ones that says it’s to much trouble, self driving cars are in your future. You’re the driver not the passenger, so DRIVE IT!

 

[340inabbody]

It’s a one wire thing, 12 volt switch. On a side note my former truck, 92 diesel auto kept burning up the OD switch at the throttle. I put a switch on the shift level to do it manually, after about a month driving it this way it became second nature to flip that switch, not much different than a manual trans in a way. For the ones that says it’s to much trouble, self driving cars are in your future. You’re the driver not the passenger, so DRIVE IT!

I agree 100% I drove 4-5 speeds for 50 years. I ALWAYS knew what gear I was in and my RPM’s. The machine interaction and interface is what it’s all about. I also been riding motorcycles since I was 15 back in the seventies and still ride my FZR AND KTM Duke.

 

[plymouth4onthefloor]

Maybe EFI controlled? If you want to upgrade!

 

[340inabbody]

Maybe EFI controlled? If you want to upgrade!

EFI ahhahahaha never! At least not for me.