Why do you need overdrive lockout?

[Bobcat698]

Why do you guys need a overdrive lock-out switch on the Allison Transmission if you can just put the shift lever in the "3" position.
It is my understanding that the "3" position will let the Allsion use either 3 or 4th gear, so why do you need 5th gear lock-out?

Just wondering, this has me flabbergasted enough to post about it :eek: :confused:

[dave p]

try droping yours into 3ard and increase the speed and see what happens. i have, and was over 70 and it was still in third and engine screaming. dave p

[csimo]

If you drop it into 3rd it will go into 3rd gear as long as the downshift would be under the red line. Once it hit red line it would upshift to 4th.

On a 01 or 02 without the added lockout button there's no way to lock out overdrive. GM corrected this on the 03 models, and there's a tech bulletin on hot to retrofit a lockout on the 01 and 02 models.

I already have the switch on my 02 and I love it.

[SDWA]

Spill the beans! How do you modify an '02 for the switch!

Scott

[JEBar]

csimo ..."GM corrected this on the 03 models, and there's a tech bulletin on hot to retrofit a lockout on the 01 and 02 models." What is the cost of this retro? Where do they mount the button? Thanks .... Jim
:confused:

[Black Dog]

Copy/paste this link. You will need Acrobat reader.

http://service.gm.com/techlink/html_en/pdf/200207-en.pdf#dst15

[ram/tx]

Is the General doing this upgrade for trucks that are still in warranty or are they charging a fee for it? If charging what would it cost to have them put the switch in for the OD lock out?

[Cowboy_120]

So I am assuming that the dealerships already have this info, so can we just go in and refer to this bulletin and get it installed? Just one more button for me to play with!

[dave p]

csimo would you please give me the service bulletin number so i can have mine done. dave p pulsiphe@voyager.net

[csimo]

As Black Dog published above the procedure is not a Service Bulletin per se, but rather it was published in the July 2002 issue of Tech Link. Tech Link is a GM publication that goes out to all servicing dealers.

Below is the link you can read and print for your dealer. The article you need starts on the right side of page 6 and is continued on page 7. Section "TAC Tips". Article name: "Allison LCT1000 M74 Automatic Transmission 5/4/5 Shift "Busyness"".

http://service.gm.com/techlink/html_en/pdf/200207-en.pdf#dst15

My dealer did the work for free, but I'm told that you should be charged under $200 for this installation.