Transmission Tow Mode

[glenalt]

I have a 2005 5.9 cummins auto trans. When I put it into tow mode it downshifts for a short while and as soon as I let off the throttle it shifts like normal. Should it stay in the lower gear and should the TC stay locked? Thanks, Glen

 

[cerberusiam]

TH on an 05 is just more aggressive shift patterns and lockup algorithms. It will shift the same as non TH just more aggressively into all the gears and OD.

So the answer to your question is no, it will not stay in lower gears. It will stay in lower gears longer with heavy throttle, it will upshift fatser with light throttle, but it will eventually upshift.

 

[glenalt]

Thanks. So what happens on an incline when you want to be in a lower gear but not shift down into 2nd? Is there a way to lock it in 3rd so you could have a lighter throttle and still stay in 3rd? I thought that the TH mode would allow that but it doesn't seem to work that way.

 

[cerberusiam]

There is, an OD lcokout switch or controller. The annoying thing about TH on an 05 was once you dropped it to D and let off the throttle too much it went right back to OD. To remedy that the OD lockout was created. Cycle the TH to get it into drive and flip the switch or double tap the TH button depending on which solution you got and it stays in D with the same aggressive lockup and shift algorithms.

 

[Hoefler]

The was a TSB with a flash that would change the TH button to an overdrive lock out. You had to choose from the modified shift points, or have the flash, ( which is not reversible ) and lock out overdrive and have normal shift points.

 

[cerberusiam]

( which is not reversible )

Oh its reversible. Just load a Smarty SW and its gone.

 

[glenalt]

There is, an OD lcokout switch or controller. The annoying thing about TH on an 05 was once you dropped it to D and let off the throttle too much it went right back to OD. To remedy that the OD lockout was created. Cycle the TH to get it into drive and flip the switch or double tap the TH button depending on which solution you got and it stays in D with the same aggressive lockup and shift algorithms.

So just to be clear, I can double tap the TH button on the end of the shift handle and it will stay in D?

 

[glenalt]

One more question about going down a hill and keeping it in a lower gear. Do I have to shift it from 3rd into 2nd or is there an option to be able to hold it in 3rd with no overdrive. Or would the same procedure of the double tap on the TH button do it?

 

[cerberusiam]

The double tap is ONLY if you have installed the BD OD Lockout controller, there is not factory option on an 05 for the double tap or OD lockout.

All you can do with the factory setup is keep cylcing the TH to hold it in drive. Everytime you engage TH it will automatically downshift to drive and wait to see what the load is. If load is high enough it will stay in D until the load drops.

A simple switch and relay will allow you to lockout OD but it is totally manual with another switch. The BD controler uses the existing TH button and a double tap to activate itself. Minor differences on how they work but the result is the same.

 

[glenalt]

Where would I find a BD controller, can I install it, and do you know what the cost is? If I have to have it installed what would be a reasonable price?

Thanks.

 

[cerberusiam]

The BD controller is about $250 I think. I thin ATS has something similar for about $150 but not familiar with it. For about $20 you can build your own manual switch setup.

I have no idea what someone would want to install these things. I would guess 1-2 hours at shop rate if they would do it. A lot of places won't do it simply for risk avoidance.

 

[CCiatteo]

The was a TSB with a flash that would change the TH button to an overdrive lock out. You had to choose from the modified shift points, or have the flash, ( which is not reversible ) and lock out overdrive and have normal shift points.

I have often wondered what exactly the TH button did on my 2004.5 and I think the TSB flash was done by the previous owner on my truck because it acts as described, OD lock out, with maybe some reprogrammed shift points, but nothing more than that. Seems kinda ridiculous, because now when towing I keep the TH off, until I'm on the highway and up to speed, but even that seems marginal unless you are really moving out. With the TH ON, I fear the transmission is kinda in-between with respect to speed versus load versus lockup and likely generating lots of heat unless you are at 70 plus, and towing I think that is not being responsible. So that means I'm stuck at 50-55 with TH OFF, unless I really want to turn some RPMS and drink fuel. I miss my old 12v 5spd so bad.

 

[cerberusiam]

On the 03-04 trucks the TH button is nothng more than an OD Off, just like the 2nd gens.

 

[p-Bar]

On the 03-04 trucks the TH button is nothng more than an OD Off, just like the 2nd gens.

Along with changing shift points

 

[glenalt]

On the 03-04 trucks the TH button is nothng more than an OD Off, just like the 2nd gens.

That's what I want it to do on my 05, to just turn off the OD. But it you take the load off and just want to cruise at 63 it shifts into OD and the rpm's drop out of the sweet spot to a place where I feel the engine could be lugging. I guess I'll have to check into the BD controller unless there is a flash for the 05. Anyone know?

 

[cerberusiam]

There is a flash and you loose the aggressive TH features that are there now. Whether or not the older systems actually chnaged shift patterns and lockup algorithm is a mtter of opinion. If they did change them it was no where near as good as the 05 has.

For $10-20 you can build a switch that will lockout OD and preserve the shift pattern\lockup changes, or, you can buy the controllers from BD or ATS for a lot more.

 

[glenalt]

There is a flash and you loose the aggressive TH features that are there now. Whether or not the older systems actually chnaged shift patterns and lockup algorithm is a mtter of opinion. If they did change them it was no where near as good as the 05 has.

For $10-20 you can build a switch that will lockout OD and preserve the shift pattern\lockup changes, or, you can buy the controllers from BD or ATS for a lot more.

Thanks Cerberusiam. Where can I find a schematic to know how to make and install the switch?