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?

Sure the later ones use a solenoid in the trans. All the early ones when they first came out in Mopars were hydraulic as I remember a 1979 Aspen I believe that was all hydraulic. I dont remember what year they started using the solenoid in the valve body so the PCM could control lock-up but I know my dads 88 truck had the electric lock-up solenoid in it as that year just had a one wire plug on the left rear of the trans main housing. The solenoid just controlled a bleed off (vent) of fluid pressure to the lock-up valve. John Kunkel will know which year they started with the electric solenoid in the valve body but I dont remember myself right now. Ron

The case he is using is a 999 out of an 83 Imperial. It doesn't have a lock-up solenoid on the valve body.

Info I'm seeing is that it's an 87 up valve body needed. Maybe someone will weigh in and confirm.

That, and about the torque converter options.

All 3-speeds lock up mechanically...some later transmissions in the 904 family have an electrical connection but it's for unlocking the converter only.

I cant see how that can be since the solenoid has to close the bleed (vent) in order for the lock-up valve to move so the converter can lock-up. I would consider them as an electronic controlled lock-up only because they have the PCM controlled solenoid. Even one of my Mopar 1986 training books calls them a "Electronic Lock-Unlock converter". Ron

Can you elaborate on this a little, John?

What we are trying to accomplish is to protect the lock-up clutch during heavy throttle 2-3 shifts. The full mechanical L/U valve body simply locks up the converter when it shifts into direct over X output shaft speed, which is probably about 45 MPH. The way I read the flow charts - no, you can't use the solenoid to lock the converter at will, as in 1 or 2 - it must be in direct to apply L/U. But can't the solenoid be used to selectively control L/U in direct? It seems to just bleed the signal pressure off going to the lock up valve to prevent the L/U valve from sending apply pressure to converter. We would like to be available to control L/U with a vacuum switch, toggle switch, or both.

So is this possible, or am I missing something here, such as also losing apply pressure to the front clutch, etc.

Thanks for any input you can provide.

I could be wrong...disconnect the wire and see if it locks up.

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.

So, do you apply power to close the solenoid and enable lock-up, or apply power to open the vent and disable lock-up?

It has to have a few things before it will lock-up when it uses the solenoid. As John says it is done mechanically and electronicly when it uses the lock-up solenoid. One of my training books says it started the electronic lock-up/un-lock in 1986. The trans has to shift into second gear so the 1/2 shift valve will send line pressure to the lock-up valve and also past the lock-up solenoid where the pressure is vented until the engine controller (PCM) decides that the vehicle is going fast enough , the eng is over 150 degrees , the PCM knows the eng is not at idle and knows the TPS posistion and the eng vacum is correct for lock-up. Also the trans has to have shifted into third gear so the 2/3 shift valve will send line pressure to the Fail Safe valve and cause it to move over. Once in third gear and the Fail Safe valve moves over and when all the criteria's are met the PCM will ground the lock-up solenoid and cause the line pressure from the 1/2 shift valve to move the lock-up valve over which then lets line pressure from the rear clutch circuit push the switch valve over. When all that happens the line pressure from the rear clutch circuit goes through the moved over lock-up and fail safe valves to the switch valve which moves and redirects line pressure to the converter in the opposite direction which then pushes the lock-up piston in the converter on and locks up the converter clutch. Does not matter if it has what they call a part throttle unlock relay as the relay still powers the lock-up solenoid on or off as the relay is still controlled by the PCM to control when the converter locks or unlocks.
Solenoid off means the line pressure from the 1/2 shift valve vents and will not move the lock-up valve so the converter will not lock-up. When the solenoid is turned on by the PCM then the vent is blocked so pressure builds to move the lock-up valve over and gives you locked up converter. Ron

This probably answers my question - I had already studied the hydraulic charts and knew the fluid side of it. Your training books must be for the later 2 wire solenoids, since you mention the PCM switches the ground to the solenoid. Both the V/B's we picked up yesterday have 1 wire solenoids that ground through it's mount, and would need 12V+ power applied to function. We will probably just wire a toggle switch supplying power and see what happens once it's in direct.

Thanks for the replies

Actually you are right as the 86 models and some other years do have one wire to the solenoid and its a 12 volt wire. The PCM is controlling the relay coil winding ground which in turn send 12 volts to the solenoid. Sorry as I am used to the PCM controlling the ground and forgot its the relay (trans lock-up or also called Part throttle un-lock relay) ground that the PCM controlls. Ron

Here's a wiring diagram of the unlock solenoid. Power to the wire unlocks the converter.

Here are some pages from one of the 86 training books I have from Dodge. This is a brief wire diagram in it. Ron

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

This is from the same book as it shows the solenoid venting in unlock. Ron

And this shows the solenoid on (not venting) and the valves all in the lock-up possition which have the conveter locked. These are all from a training book that I got at training at the Dodge dealer in 1986. Ron

I can tell you this,I removed the computer from my 88 d150 with one wire lockup.
Now there is no lockup.
If it was locked up it would most likely stall or near stall the motor at idle.

Thanks for all the replies.

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.

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. Pretty much everything fuel injected after 1988 had the electronic solenoid controlled lock-up. It was better to let the controller (PCM) work the solenoid to control lock-up as the PCM could moniter everything real easy like MAP vacum , eng speed and temp , vehicle speed and TPS posistion so it made it easy for the PCM to know when the lock-up should be on and it was just a simple ground the PCM controlled to control the lock-up conveter. Alot of them used the relay that the PCM controlled to send 12 volts to the lock-up solenoid. And it does not matter what the relay was call as.... part throttle unlock or lock-up solenoid as it always controlled turning the lock-up conveter on and off. You can see it very easy if you look at the flow charts I posted. Its really a very simple system. 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.

Without power it'll unlock too, just not at part throttle. It's a fail safe design.

M bodies has carbs till the end of production.

John when I look at the flow charts from my book it says the solenoid is deenergized with lock-up off (venting) and energized (not venting) is when it locks-up which is when the PCM grounds the relay and sends the 12 volts to the solenoid. Ron

From a safety standpoint it would make more sense to engineer it to not work if the control circuit fails rather than to not release. Using that logic - if you apply power to close the solenoid (vent) to lock the converter and the control circuit fails, you only have a no apply issue. If you have to apply power to open the solenoid (vent) to release the L/U and the control circuit fails - the converter won't unlock when instructed and could be a safety issue, even if it only happens in 3rd gear.

Kinda like the air bag circuit - would you wire it so you have to apply power to work, or to keep it from working?

Next time I visit my buddy with the trans I'll pull a solenoid off and see if it holds or vents pressure at rest. I think it will vent.

Y'all are thinking it only unlocks with the solenoid, at least on the M bodies that is not so, it will unlock hydraulically just like the non cop spec ones.

I think we are really talking about two different systems, one for PCM controlled EFI systems and the other for lean burn carb systems.

Both right, but in different applications.

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

W-R-O-N-G

Show me one car with all that on it and an A998 in it.

You cannot as it was never made.

Trucks, yes, cars NO.

That's the point.

The car version does not, nor ever did it, do any of what you say.

Trucks, maybe I do not know trucks.

I have the A998 out of my old 87 Dodge Diplomat and it has NONE of what you claim in it, it's a civilian version.

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

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.

Here's the transmission the OP is using

The case he is using is a 999 out of an 83 Imperial. It doesn't have a lock-up solenoid on the valve body.

Not a truck and no unlock solenoid.

Here is what the OP asked SuperCuda. I took it as telling him how some of the 900 based tranny's DO have lock-up and how they work. Thats all plain and simple. I did not say all M-bodies have lock-up as I dont remember off the top of my head which body styles did or did not have lock-up. I go to the service manual for the year and body car I work on to determine all the options as you cant remmeber all of them off the top of your head. Get the M-body deal out of your head as I only used what I said as reference about how electronic lock-up works. I could care less what year M-bodies use electronic lock-up. I only wanted to tell the OP how they work and how the solenoid lock and un-locks the converter. Maybe you should worry more about how the electronic lock-up works which is what the OP wants to know instead of whether I know which year M-bodies had electronic lock-up because I dont care what year M-bodies were or were not electronic lock-up. My point was to let the OP know ALL ELECTRONIC LOCK-UP converters are turned on and off by the solenoid when they have the electric solenoid. If you cant understand that then learn how to read a flow chart. Ron

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

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

Yes,I bought higher stall lockup convertor,I believe it is around 2200-2600.

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.

EDIT: THey could have with police to save the lockup cluth. But just because the wiring diagram shows it doesn't mean all models had it, the diagrams don't always distinguish between stock and optional items.

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The Mitchell hydraulic flow chart (Fig 5) also shows the electric lock-up solenoid in the trans in '88.

At this point - my original post was - do electrically controlled lock-up valve bodies exist? YES, THEY DO. Application? NO ONE CAN AGREE (Doesn't matter at this point - we found and bought 2 one wire lock-up V/B's). Better torque converter? NO REPLIES

So our best bet at this point is to just wire a toggle switch to the flippin thing and after we figure out where on and off is, mark it with a sharpie.

You're missing the point, the word "unlock" is used in most of the references to this feature posted here meaning, to me, the solenoid is energized only for unlock.

We both agree that the solenoid valve opens to vent the circuit and unlock the converter but the disagreement is whether the solenoid is energized to close the valve and lock the converter or whether it's energized to open the valve and unlock the converter. I see no absolute proof of either here.

Perhaps I'm too pragmatic but it seems to make more sense to energize the solenoid for a short period of time to part-throttle unlock the converter rather than to have it energized the whole time the converter is locked up.

As noted earlier, before the solenoid valve, the converter locked and unlocked hydraulically based on road speed/throttle only...it would unlock under some heavy throttle activity or when the car slowed enough for it to shift out of third and shut off the fluid source to the converter lockup circuit . To my way of thinking, the solenoid valve was installed to make the unlock at speed more controllable to answer driver complaints that forced unlock wasn't consistent when based solely on road speed/throttle pressure.

John I agree that they went to the electronic lock-up with the solenoid for better control of when to lock the conveter since the PCM basically moniters everything. It only makes sense the PCM can control lock-up better then the older hydraulic way. The solenoid is energized when the trans converter locks and deenergizes when it unlocks. My training book even says..................Part Throttle unlock will happen between speeds of 40 to 55 mph. It watches for the manifold vacum to go above 20 inches or below 3 inches of vacum in the 40 to 55 mph range. If this happens the computer (PCM) will deenergize the solenoid which vents line pressure going to the lock-up valve. The lock-up valve then goes to its unshifted posistion and unlock will occur. Lock-up will reoccur when vacum comes back down to 18 inches or up to 5 inches. At those points the PCM will energize the solenoid so line pressure will shift the lock-up valve and lock-up will reoccur.

I am not trying to be a smart a$$ as this is just what it says in one of my Mopar training books. It also says how the solenoid deenergizes at idle and WOT to unlock the converter. I dont mean to offend anyone and I apolligize if I did. Ron

The hydraulic chart doesn't mean anything, they would have used one set of charts for the type of transmission and not the application it was going in. If the application doesn't use it they just expect you to omit that information in the manual. The actual description of how it works in the manual and the breakdown diagrams of the lockup components at the vale body do't show the electronic parts. As for application, everyone has agreed that the fuel injected trucks have it. Cars don't. I would take what's been said in this thread over what a Mitchell manual shows.

If was trying to make this work I would get a copy of the factory truck service manual to at least verify the Mitchell information.

John can correct me if i'm wrong but I didn't think under hard acceleration it locks up anyway. Some of those transmissions you can tell when they've locked up by the way it sounds or feels and usually it's when you're already in 3rd gear that it engages.

Pretty much once you've built a 904 to take the power the weakest link is the torque converter snout. After my last 904 died I put a 727 behind my 360 and called it done.

Don't see that quote in any of the material you posted. If you'd posted a pic of that quote from the gitgo you coulda saved a lot of bandwidth.

It did not state that in what I posted but I have said it a few times that the solenoid is deenergized with lock-up off and energized with it on. Since no one believes me here is a page where it actually says this info. Ron