Finally- a fix for the lack of OD lockout on the 2005

[GaryCarter]

Haven't seen any previous posts on this product-



If you have the '05 then you know DC in their wisdom gave us just "Tow/Haul", but no way to lock out the OD.



Talking today with ATS about solutions, and find out they have a new kit to fix this. Ordered it on the spot. Has anyone yet used this kit?



I'll post back a report after I get mine installed.



Gary

 

[SAlex]

Joel at J an H diesel had a wiring schematic and some capacitors and a wiring switch. we built our own. Hard part is keeping trans out of limp mode with the right diode. Steve

 

[Morse]

Gary, what was the cost? Thanks...

 

[Reb.B]

its easy to make and its easy to keep trans out of limp mode, but i was always scared the engine would go into limp mode and drop a couple hundred HP until reset. All you have to do is put a mystery switch (ground switch) to the O/D wire and then run a keyed hot wire to the trans relay and it'll work fine, but i'm scared of the engine going into limp and having to use a code reader to get it back on the road running good again.

 

[MRosinski]

Finally, i've been waiting since I bought the truck. Please keep us posted.



Thanks.

 

[ModifiedDiesel]

Don't you have to worry about overspeeding the engine if OD is locked out at a high speed. I'd hate to accidently hit the OD lockout switch when going 90mph down a dragstrip.



I'm sure the non-05's won't let the transmission downshift if you are going to fast and hit the OD off button

 

[Reb.B]

i think people are wanting to LOCK IN the overdrive, but if you wanted it both ways then just go with a sigle pole, double throw switch and then have the controll of O/D at you fingers

 

[ERohloff]

Agree this O/D switch would be nice to have BUT suspect it would put the transmission (perhaps the entire drivetrain) warranty in jeopardy as do any add-ons. And not sure removal before warranty service work hide the fack either... ... Food for thought.

 

[cerberusiam]

Don't you have to worry about overspeeding the engine if OD is locked out at a high speed. I'd hate to accidently hit the OD lockout switch when going 90mph down a dragstrip.



I'm sure the non-05's won't let the transmission downshift if you are going to fast and hit the OD off button

I don't think this is a racers mod. :-laf :-laf

i think people are wanting to LOCK IN the overdrive, but if you wanted it both ways then just go with a sigle pole, double throw switch and then have the controll of O/D at you fingers

No, we want and sometimes need, an OD lockout. You can't just wire a switch in and leave an open circuit or it will go into limp mode. You have to fool the ECU into thinking things are cool while removing the ground from the OD circuit. Yes, it would probably void the warranty.

 

[Reb.B]

yes you can leave a wire open. when you ground the o/d wire or leave it open when it shouldn't then you need to put a hot wire from the key to the trans relay. There is one port on the relay that puts power to the trans solenoids. pull the relay out, put the hot wire to that one port and the trans will not go into limp. BUT and this is a big BUT, the engine may go into limp, and if this happens then the engine will drop a couple hundred HP.

 

[Reb.B]

I lock my O/D and my lock up on my 03 when i dyno so that the trans will not come out of O/D while on the dyno. All 05 trucks should do the same so they can get accurate readings

 

[cerberusiam]

and this is a big BUT, the engine may go into limp, and if this happens then the engine will drop a couple hundred HP.

This is why jumping the relay is a not a good solution. In addition there is a difference between what an 03 is managing and what the later ones are. If you jump the relay and push the power it will code and go into limp mode.



You cannot leave a signal wire to the ECU open nor can you ground one completely or it will throw a code. You need to replace the feed from the OD solenoid with a 12 volts ressited to the correct level so the ECU or trans relay has no reason to suspect there is a problem. It works the same way as the lockup switch by maintaining a resistance that the ECU can read.



The stock 05 VB will not allow a down shift once the TC is manually locked. There is no need to lock these trucks into OD for a dyno run or otherwise. Locking out OD, however, is quite usefull when towing at slower speeds to keep the engine at a decent operating rpm.

 

[Reb.B]

cerberusiam, ... . you are sooo wrong. Several reasons you are wrong. Jumping the relay WILL NOT put you in limp mode! FACT. The stock VB WILL DOWN SHIFT on the dyno if you nail the power below 1800 RPM FACT. thats why when 05 autos get on the dyno, it takes the dyno operater twice the amount of time to get an accurate reading. NOW, the paragraph about leaving the signal open to the ECU is correct. You are right there, and thats why you put a hot wire to the relay and solenoids.

 

[cerberusiam]

cerberusiam, ... . you are sooo wrong. Several reasons you are wrong. Jumping the relay WILL NOT put you in limp mode! FACT

What gives? YOU posted this, not me. I just agreed with what you said and offered another way to avoid it. Why am I wrong for agreeing with you?



As far as downshift when locked. Mine has not done it WOT on the road or dyno, empty or dragging 10k, under 1800 rpm's. FACT. Maybe jumping that relay has some side effects that are not so obvious, huh?

and thats why you put a hot wire to the relay and solenoids

I will say it again, there is another way to do it without jumping the relay that works WITHOUT the chance of coding YOU brought up. Done it. It works. FACT.



Reb, I am dissappointed. I expected a bit more of an open mind from you. If you are unwilling to give anybody else a little credit for finding solutions that work, I am not gonna debate a moot point.

 

[Reb.B]

you posted that that jumping the wire is not a good solution, when it is. Over and over again 05 auto down shift when trying to dyno. So, you are saying that on your truck you have removed the ground from the o/d solenoid with out the trans going into limp by fooling the ecm?

 

[cerberusiam]

So, you are saying that on your truck you have removed the ground from the o/d solenoid with out the trans going into limp by fooling the ecm?

No, I lock the TC with a switch run thru a resistor to fool the ECU into thinking it has control. This negates the need to jump the trans relay to avoid coding. With the TC locked with the switch, I do not have a down shift to drive when I give it full throttle. With the stock VB when the TC is locked it won't allow a downshift. This may not work with a modified VB as I believe that restriction can be removed.



This works on my 05, and several others also. There is enough differences between the wiring, ECU's, and resistances that I would not bet it would work on every single truck.



The OD lockout is an interesting piece because under 60 mph with a load the trans just bouces back and forth from OD and never wants to settle and lock. Its not meant for dyno aspect, just the work aspect.

 

[Reb.B]

Okay, cerberusiam, trying to make sence of all of this. I believe what you are saying and i understand hydrolically why your way works, but i don't totally understand electrically. If you don't mind i would like to pick your brain. This fix that you have should work on 05-06 trucks hydrolically and some 04 trucks. The reason why is that the O/D oil can not be exhausted when the lock up is on. Some poeple were putting a 30 ohm resister in the wire grounding the O/D. Why does the cumputer want to see resistence when it is not commanding the lock to stay on? If one was wanting to get rid off O/D at times what do you think of using a resister and using a one way diode in line. This way the ground (or lack of) on the O/D wire would not be shown to the computer. I was under the impression that the PCM would calculate ratio diffence and would go into limp if forced into O/d or forced to stay locked, but if it doesn't and you don't get a code, then we should be able to force it out of O/D as well, correct?

 

[cerberusiam]

Both the OD and TC circuits spec a minimum 5 ohms resistance and a minimum of 0. 5 volts. My interpretation is the ECU is not only checking voltage but also resistance on the circuits to determine if they are functioning correctly. Theoretically, until I get a chance to try it that is, one should be able to do the same thing on the OD circuit, ie a 30 ohm resistor to ground to activate the solenoid and keep the ECU happy. From what you say that is what is happens.



The question I have with the OD tap is what happens to lockup? If you don't lock it also won't it drop out of OD under full power? The reason I chose to lock the TC is that ensures it staying locked and staying in OD.



Locking out OD should be just as simple. Provide a 12 volt feed resisted in the range the ECU expects. When it calls for OD and grounds the signal wire there is no way it will know if the signal comes from the OD solenoid or a clever little box. I suspect that is what ATS's solution is all neatly packaged.



The FSM also specs voltage and resistance ranges for the trans relay. I suspect that is why there are codes produced when you jump the relay. Under certain circumstances the signal is too high for too long and the ECU just shuts down the relay and you have limp mode.



So far I have had no problems with the TC lock switch. Have locked it in 1st thru drive and let it upshift as it wanted. Locked it in OD to hold more power on a pull. So far no codes so I suspect the stock trans is more in danger of damage than it is of throwing a code.