47RE Torque Converter Lockup Disable Switch

[balsip]

I found my recent 2000 2500 truck aquisition very annoying constantly going in and out of lockup in the city or in hilly terrain so I installed a switch on the dash to disable the lockup solenoid. The extra lock-up sequence in 3rd gear was even more annoying as the 97 does not do this. This is not the "mystery switch" that forces a lockup and in fact is the opposite. The mystery switch is vey hard on the soft parts in the tranny when changing gears locked.I had done this in my 97 2500 and all I had to do was put a simple switch in to open the circuit to the solenoid. Last week I tried the same thing in the 2000 but it immediately went into 3rd gear limp mode. New software in the 2000 PCM so I had to take a different tact. I finally ended up switching in a 150 ohm 5 Watt resistor connected to switched 12V with a relay to make the PCM think the solenoid was still connected. The relay is activated with a round rocker switch on the dash that looks factory. The relay has a 75 ohm coil but the higher the resistance that does the job the less current required. If anyone else is interested I can post the circuit diagram. I basically cut and spliced in the circuit in series with the OR/BK pin 11 on connector C2 (middle of the three) on the PCM. No codes get set with this circuit. The relay can be eliminated by using a STDP switch but its hard to find one that looks factory. The switch has to be 2 position only and not a 3 position or a code will be set saying there is an "open solenoid circuit". The hardware is mounted immediately beside the drivers side hood hinge on the small ledge inside a small electrical box with a 4 wire trailer connector. This is my 1st post on this excellent site so I will fill in the signature once I figure out how.

[JOHNFAK]

Hey. Cool info. Now I am still a bit of a newbie so forgive the questions. Whats the purpose of bypassing the lockup solenoid ? I mean - I get the purpose of the mystery switch to force TC lockup - but aren't you kinda trying the reverse - to prevent lockup until you decide to turn it on ?? I couldn't think of why that would be what you wanted - at first I thought for racing - but then that didn't quite make sense when I thought about it - so kinda lost me With the TC off and not locked up - I guess your enabling higher rpm (hence why I thought racing) but then you lose conversion efficiency - so thats why I dropped that idea. So it will generate more heat in the TC and tranny fluid, and less power to ground. Anyway - sure I missed the point - either way its pretty cool info when someone posts internal modifications - something you can alwayts reference if its useful to your application - so thanks. Waiting more info

[balsip]

The main reason is reliability and longevity of the transmission. Many drivers do not realize that every time you release the throttle the lock-up clutch disengages. Because the Dodge diesel has a very loose TC (inefficient fluid coupling) the clutch has to absorb 300 to 500 of RPM difference when locking up. This was fixed with the 48RE since many heavy towers could not engine brake with an automatic. Anyway this yoo-yoo shifting in is not a problem at hiway speeds but in the city it puts a lot of extra wear on the clutch. I would prefer to lose the 5 to 10 per cent milage loss with it unlocked in the city unless on a long hill climb. I got 450,000 km out of my 91.5 Dodge non-lockup tranny and most people get much less with the 47RE lock-up TC. The 1999 to 2002 was especially demanding on the TC clutch because Dodge added an extra lockup in 3rd that really is not much use over the narrow band it is engaged.

[Mopar1973Man]

Might be an idea for Mom's 96... That trans is constantly jumping back and forth and locking and unlocking the TQ converter because of every little small hill. Gets annoying... I thought of doing a lockup switch and locking the TQ but it might be the idea of keeping it unlocked till I get out on the flats. Lets see the wiring diagrams... Pics wanted!

[JOHNFAK]

The main reason is reliability and longevity of the transmission. .... Anyway this yoo-yoo shifting in is not a problem at hiway speeds but in the city it puts a lot of extra wear on the clutch.

Now I know why my stock TC was almost trashed Haven't driven it enough with my new 3x disk - but expecting a few miles on it from now - am gonna put in a derale cooler as well. Yes - pics !!! Cool info.

[balsip]

Here is the circuit. I used pdftown's 2001 Ram manual to get the original factory cct drawing in sec 8W-31 page 3. I can thank this site for that! I just copied it and marked my changes in pencil as a guide. It is a simple enough circuit but it was surprising how long it took me to make it look good when putting it together. I used the same 5 pin relay used in the power distribution centre under the hood on the drivers side fender. I bought a spare at an auto supply store. I did not have the proper socket for the relay so I used female blade crimp on connectors instead. I added heat shrink to each one to make sure no shorts could happen. All the circuit was put in a 120 VAC metal wall switch box (surface mount type that has rounded corners and blank metal cover) and used a 4 conductor trailer connector so I could easily remove it for maintenance. I tie wrapped the relay to the side and dabbed it with silicone to make sure it would not move in the box. SPST switch at bottom is the dash switch for the driver to turn the relay ON/OFF. OFF is the normally closed position of the relay so it defaults to TC clutch engaged. Do not use one of those lighted auto switches or the current for the LED could be a problem (would have to test relay pickup current). For a 12V supply I used the 10 amp radio cct that also supplies power to my LP Fuel Pressure Alarm so current is only drawn when key is in ON position so battery draw is zero while parked. The BD LP Fuel Alarm kit came with a "fuse tapper" so that made it easy to tap power off the fuse. By the way, a 1996 Ram can get away with a simple SPST switch with no limp mode. There will be a code in there but it will not light the MIL indicator and is hidden. The above circuit just makes the computer think it is still connected to the clutch solenoid coil at all times. It is measuring voltage across a small resistance in the I/O circuit that effectively checks for minimal current to show connection to tranny is good. I am not sure if I got this picture link right but I will try to learn how from others.

[jncornett]

I am planning to do this very thing just to get rid of smoke when driving through the 45mph zone near my home, while towing after the new turbo and injectors it hazes way too much for my likeing whether in 3rd or 4th when it locks at low speeds ....anyway thanks for the leg work... i hadnt started working on this yet but next week will be a different story... my new goerend gets installed wednesday :hyper:

[balsip]

Let me know if you want a picture of the installation. There are probably better boxes than a duplex electrical box to stuff the relay in but it did the job. Also, you may be able to find a relay socket easier than I could here in the far North. Radio Shack (the Source in Canada) has a black rocker switch that matches our dash in the Dodge that makes it look "factory installation".I am wondering whether your haze may be due to the need for more air from the turbo? A 100 hp increase at injectors may need a small orifice leaking to atmosphere on the actuator air line (via a brass fitting) to make it open wastegate later and provide more air for combustion? The other possibility for the haze mentioned to me is too thick of a copper washer on the injectors causing the injectors to be too far out of the combustion chamber. I know my 91 has 0.030 washers and produces haze at idle since they should be 0.020 which I stupidly missed in the instructions when installing. I'll change them next time I clean the injectors.

[jncornett]

Let me know if you want a picture of the installation. There are probably better boxes than a duplex electrical box to stuff the relay in but it did the job. Also, you may be able to find a relay socket easier than I could here in the far North. Radio Shack (the Source in Canada) has a black rocker switch that matches our dash in the Dodge that makes it look "factory installation". I am wondering whether your haze may be due to the need for more air from the turbo? A 100 hp increase at injectors may need a small orifice leaking to atmosphere on the actuator air line (via a brass fitting) to make it open wastegate later and provide more air for combustion? The other possibility for the haze mentioned to me is too thick of a copper washer on the injectors causing the injectors to be too far out of the combustion chamber. I know my 91 has 0.030 washers and produces haze at idle since they should be 0.020 which I stupidly missed in the instructions when installing. I'll change them next time I clean the injectors.

Sure pictures would be great.... As far as the haze it is from low boost at the lower speeds.. wasnt an issue with the factory turbo... Now with the 62-12-65 that is on it the truck produces2- 4 psi where it used to be about 10 at 45 mph locked up.... I was told this charger produces 930 cfm and should be flowing approximately the same amount of air at 15 psi as the stock hy at 25...It lights very fast and as far as the boost actuator goes i blocked off the line trying to figure out why the wastegate opens at 22 psi just to make sure my chip was actually boost fooling... After a call to the manufacturer i was informed the info that was provided wasnt exactly correct.. I was led to believe the wate gate was set to 42 psi and the manufacturer says is set to more like 30 ish but was confused that it was opening so soon..when i get time i need to shorten the waste gate actuating rod to get the pressure set where i want it... The haze isnt dark but i realy dont like seeing smoke no matter how light it is......

[AH64ID]

So what does this do for temperature? One of the main benefits to lockup is lower trans temps.

[jncornett]

So what does this do for temperature? One of the main benefits to lockup is lower trans temps.

Not alot.... If you were to drive long distances you wouldnt want to do it due to temps, but im only looking for the 2 mile business district that i tow my lawn service trailer through during rush hour on my off says from the fire house. If speeds are at or below 45mph that darn truck lugs and hazes... Any thing after 32 ish in drive and everything is at temp.. it locks up and doesnt like to unlock...and at about 42 in od same deal.... This truck of mine is stuborn once that t/c loks up it dont like to let go and it gets pretty smokey if you press down to power through to unlock/down shift or up to enough rpm to build boost...Darn auto's lol hopefuly not a problem after tomorrow the goerend unit went in today and will be finished up for pick up tomorrow and my problems may be over with stuborn lock up time will tell

[balsip]

I would recommend that the TC stay locked when towing hard to keep heat down. I mainly use this switch to unlock in the city to keep the TC from cycling lock/unlock since it is the prime cause of 47RE premature failure. When the TC clutch slips the debris gets stuck in the anti-drainback valve and blocks fluid flow and that is the end of the tranny. Many rebuilders remove the drainback valve which my 91.5 did not have from new. It just takes 10 seconds to fill the TC on startup before you can feel engagement. Anyway here are the promised pictures. The 1st is the switch on the dash with a BD low fuel pressure light just above it. I put it on left drivers side near fuse panel for easy access. The power was taken from the "fuse tapper" that came with the low pressure kit and was intalled on the 10 amp radio fuse. Extra load is 0.1 amp max. (or 100 mA). The relay is only energized when the dash switch is ON and the ignition key is in ON or ACC position.Left drivers side dash at fuse panel. The electrical box with relay and switched 150 ohm 5 Watt resistor under hood. Yellow wire is two conductor that is connects to C2 at PCM to tap into the TC solenoid wire OR/BK.Under hood installation The guts of the electrical box. I used flat blade connectors insulated by heat shrink to connect to relay and prevent shorts. Tie wraps are handy to keep box steady and parts from vibrating.The relay box with a NAPA relay basically same as those used extensively in the power distribution box (the big black box with fuses, fuseable links, relays beside the drivers side battery). Note the 4 conductor trailer connector for easy removal if ever required. I put this under the hood(rather than the dash) because I did not want to complicate the procedure for removing the dash when an HVAC exchanger needs service down the road. Let me know if any clarification is needed and good luck.