View Full Version : adding tow/haul mode to an older 4L60E
10-24-2011, 06:59 PM
a thought occured to me today...is it possible to add tow/haul mode to an older 4L60E? i would like to add it to my '98 if it's not too complicated. i mean, i don't know that i'll ever tow/haul anything real heavy...but i figure if i do my V6 could use the assistance of tow/haul mode probably more than a V8 truck could...
i just wonder how it works. does it go into the PCM and change the shift commands for the transmission? or does it go into the transmission itself and change it's behavior there? i would guess it alters it at the PCM...just wondering if anyone has any info on this...thanks in advance for humoring my crazy idea!
10-25-2011, 06:33 PM
Well, it should all be in the TCM or transmission control module.
What T/H does is lock the converter sooner should be 2nd gear. Stops TQ slip and helps keep heat down.
It shifts later on upshifts, helps keep your engine in it's power band to pull.
Raises line pressure (not sure how much) helps keep the clutches from slipping.
The TQ stays locked longer to help slow you down when the trans down shifts.
Downshifts sooner to help slow you down
Part of the problem with this is you have (to my knowledge) 2 trans tunes. (this is coming from Allison info, GM is different, but Allison had it first)
One from normal driving and one for trailer towing, special tune stuff whatever.
The T/H button just changes which tune your using. I am sure it's not all that much, but you do have two different programs to a point atleast.
As far as your truck. I would say yes and no as far as being able to add a T/H. I'm sure if you had some money and knew or searched out and paid the right people it could be done.
For you to do it yourself. It still can be done persay.
The line pressure you can do with a shift kit, by product is a firmer shift. (how firm depends on the shift kit)
The TQ lock you can get a wiring kit or control kit and do yourself.
The shift timing or shift points you would need a retune and would likely not like it for every day. I would recommend manually shifting for that. The only time upshift will be real different is with a lighter foot, but you can shift up manually also.
I can tell you have I a shift kit in my 96, B&W stage 1 towing shift kit. If I stomp on it, it can shake the bed when it hit's 2nd, 3rd is not so hard 4th, is softer still. Downshift is not bad at all. (none of this bothers me)
Light foot it kicks a little going to 2nd, 3rd and 4th aren't to noticable. If you let off or drive like a dead grandma then you don't feel a difference.
So for the cost of a shift kit and TQ lockup controller, and free manual shifting yes you can have a "T/H button" Problem is you have all the characteristics all the time.
Oh don't think I added, shift kit will raise line pressure and firm up shifts just like T/H. As I said the kit and stage, tow/street strip makes a difference.
10-25-2011, 08:24 PM
I saw this on another forum. It may answear your questions.
My neighbor bought the B&M version of the electronic shift kit. I tested the box with an ohm meter and found out that it is just a set of overly expensive resistors. Position one read around 27 ohms and position two read at 5.6 ohms. After looking at the instructions and the 411 swap sheet posted on FSC (a huge thanks to who ever made that spread sheet, it helps in so many ways) I found out all the switch does is fool the computer to think the fluid pressure is low during the shifts. This makes the transmission increase the pressure in the shifts and makes the "harder" shifts.
http://www.fullsizechevy.com/forum/images/smilies/evillol.gif Time to introduce the $3 transmission shift kit. All you need is a pair of 10 watt, 10 ohm resistors sold at RadioShack for $3. When wired in a series the add up to 20 ohm's, just a little firmer than the position one on the B&M. This is what I have used on my 4L60-E Tahoe for the past month. It works great.
If you have a black box PCM, which is stock on the 96-00 Vortec's, the resistor needs to be spliced between pin 6 and pin 16 of the white connector on the PCM (top right when looking from the engine.) To make it shift harder, you could even install a switch which would give you the option to use only one resistor of 10 ohms. The 10 ohm was two stiff for me so I just left it at 20 ohms.
PC Solenoid High - red/black - C3, Pin 6 (411 PCM: C2, Pin 6)
PC Solenoid Low - lt. blue/white - C3, Pin 16 (411 PCM: C2, Pin 8)
10-26-2011, 08:49 AM
thanks a lot you two! i really appreciate the input. i might try the resistor trick...
11-14-2011, 02:39 AM
Any info if this follows into the 4l80e as well?
11-14-2011, 04:29 AM
i'm not real sure, but i would think it'd operate/be controlled on the same principles...just with different parameters...maybe someone else can chime in. i haven't done this to my 4L60E yet...
11-14-2011, 10:48 PM
If you wanted to run two different shift schedules, you could just replace your TCM with an aftermarket one. Like a TCI or Compushift. A lot of the aftermarket ones with let you toggle between different shift programs and are plug and play.
11-15-2011, 04:15 AM
hmmm...never thought about that...how would that work with the stock PCM? i mean, it would still be there for the engine...and it would be expecting to call the shots for the transmission...or do you have it custom tuned to think a manual is in the truck?
thanks for the post bud!
11-17-2011, 07:49 PM
subd for later use
11-21-2011, 08:17 AM
do the 0411 PCM swap and add a wire to the truck, to a momentary switch
11-21-2011, 06:26 PM
wow, it's that easy?! see, that's what i was hoping for. thanks Dave!
11-21-2011, 09:25 PM
If the truck has cruise control, the PCM should also have second set of shift tables for that mode. I once saw a thread where someone wired a switch to a wire on the PCM that would kick the PCM into those shift and pressure tables without engaging the cruise control itself. That might be a viable option.
I would just add a shift kit though. With the Transgo HD2 you can manually hold gears with the gearshift to any rpm, and it disables the PWM on the TCC fluid circuit, which ends the problem of partial lockup toasting the clutch or the transmission. This is much better than T/H imo.
11-22-2011, 09:19 AM
yea I'll consider a shift kit. I just thought it'd be kinda cool to get in a '98 C1500 and see a newer shifter with a tow/haul button that worked...when this transmission blows it's being rebuilt with all the goodies to include a shift kit...in anticipation of the mildly built 5.3/5.7 (LS1)/6.0 that will come when the 4.3 decides its time to go...
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