Cop spec M bodies had an electrical part throttle unlock solenoid that allowed the TC to unlock based on throttle input. Lockup functioned just like the civilian version.

This would be the only case in an M body that would have had anything electrical to do with lockup. Right up to 1989 the only thing non-cop ones have is the neutral safety switch and everything else is done within the transmission itself.

This page says that the relay which controls the solenoid locks and unlocks the conveter. Ron

I know it's just semantics but, with no power on the solenoid, it locks up...power unlocks it so one (not me) could say that the solenoid locks and unlocks the clutch but in a passive way on the lock and active way on the unlock.

I dont remember on the M body as I would have to look in the service manual and look at the trans flow chart and wireing. They may have still had a carb on them.

I know it's just semantics but, with no power on the solenoid, it locks up...power unlocks it so one (not me) could say that the solenoid locks and unlocks the clutch but in a passive way on the lock and active way on the unlock.

Yes when lock-up first came out they were all hydraulic as they used gov pressure to move one of the valves so the car had to be over a certain speed and it had to be in third gear on them. You could change a spring to raise when it locked up. Then around 1986 they went to the electrical solenoid
since they were now using computers on the cars and it made it easier to have control over when the lock-up came on as the computer (PCM) can moniter all the systems better like eng speed , vehicle speed , eng temp , eng vac and the throttle posistion by the TPS. It is still partial hydraulic as it still has to have shifted into second to feed pressure to the solenoid and it has to be in third so the fail safe valve gets pressure to move. They can still control when it applies by turning on the last item needed to move the lock-up valve over which is the solenoid. It can also be confusing how they word things as they call the relay on some the Part throttle unlock relay but really it dont make sense to me as yes it can unlock the lock-up at any part throttle it likes since the computer knows just where the throttle is and all the other inputs it needs to know. So yes the relay can cause it to unlock at part throttle but it can also loc-up or un-lock the converter when ever it likes. Bottom line is on this system the torque converter can not lock-up without the lock-up solenoid being powered on and it can un-lock the converter whenever the PCM turns the solenoid power off. Thats all I was trying to say is no matter what they call the lock-up solenoid or relay it will control the converter to lock-up or un-lock. Ron

This would be the only case in an M body that would have had anything electrical to do with lockup. Right up to 1989 the only thing non-cop ones have is the neutral safety switch and everything else is done within the transmission itself.

Yes I say cars but trucks is what I worked on 99% of the time as in 1986 Mopar did not make many rear drive cars to be honest as like I said 99% of what I saw was trucks or front drive cars which also had the electronic lock-up that basically works like this. So whether I said cars or trucks I meant that I was talking about any rear drive vehicle with electronic lock-up. I was not debating which models used electronic lock-up but trucks is what I worked on most and what my mind was thinking even if I said cars. We did not not see many rear drive cars even in our Dodge dealer to much in the 80's and 90's as they did not make many. My point was to tell how the electronic lock-up works as Mopar has used other versions since the 80's. In 1989 the 604 trans axle came out which was all electronic shift and uses a LR/Lock-up solenoid along with other solenoids. But the Low Reverse/Lock-up solenoid worked the lock-up converter and the Low/Reverse clutch. It moved a switch valve to determine if it applied the lock-up or low/reverse clutch. It was a little more complicated then the basic electronic lock-up. But as I said my point was not which vehicle used the electronic lock-up it was just to show how they applied the electronic lock-up. About the only M body cars I remember even seeing come in our shop after 1986 was Police cars but we did not see many of them. So I am not wrong on showing how the electronic lock-up works as I am correct about that. The M-bodies may have still used the hydraulic lock-up in the late 80's as I did not work on many of them at all so you may be right about them. The few M-bodies I saw I did not do any trans work on them and I just dont remember what they used so I appoligize if I gave you the wrong impression that I was talking about them. Ron

Friend wants to run a 904/998/999 based lock-up trans in a 66 Dart behind a mild 360. Main question is - do all lock-up 904's shift into lock-up "mechanically" - referencing high gear applied and governor input, or are there any lock-up 904's that have an electric solenoid that dictates converter lock-up? I thought I remembered seeing a lock-up 904 with a connector at the left rear of the case for a lock-up solenoid wire. Trans didn't have a trans brake in it, before any one asks. Is there an "electric" lock-up valve body - if so - application?

And does anyone make a "budget" converter for this trans that has a little better stall and would live behind a 350 hp 360?

I only wanted to tell the OP how they work and how the solenoid lock and un-locks the converter.

Your interpretation of how it works. The word "unlock" in all the quoted examples is the operative word.

Mitchel On Demand wiring diagrams for BOTH '88 and '89 Diplomat SE's show a "Part Throttle Unlock Relay" - receives ground signal from the Spark Control Computer (org/blk wire - plug 1/pin 8), and 3 dark blue wires - 2 provide signal and input 12v+ (same dk blue wire from key that powers the coil, volt reg, alt field, etc.) , and 1 providing the 12v+ output from the relay to the "Part Throttle Unlock Solenoid" in the trans.

So, according to Mitchel, controlling the lock-up electronically started in '88.

Mitchell copied the wrong information right out of the factory manuals and it's not the only wrong bit of information in there. Electrical shows that yet the transmission section has the correct information with the valve and pressure spring and no mention of electronic control anywhere. Trucks might have gone that way but the cars never did.

Unlock means unlocked. Dont know what else it could mean. Ron