Lock out for the Allison

[Jeffrey Shaffer]

Hello I'm interested in locking out 5 gear as you cant select 4th gear on the Allison. I heard of someone having this installed. Does anyone know about having this done or if it can be done yourself. I have an 02 I heard they have them on the 03's it sounds like a nice feature to have to get egt's down when towing. Thank for an info Jeff

[SoMnDMAX]

Read this-

http://forum.62-65-dieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=7&t=003361&p=2

Should help you out... If not, post back, and someone will walk you thru the installation.

[Kennedy]

Comes as part of a reflash update for the TCM. You then need to attach wires connected through a momentary contact switch to pins 12 and 28 on conector C1 (lower of the two) to operate.

[Jeffrey Shaffer]

It would be great to get you to walk me through the installation. I called the dealer today said they never heard of installing a lock out. Lot they know.

[mackin]

Jeff,

Check this out =>http://service.gm.com/techlink/html_en/

Scroll down to Tac then if you have Acrobat Reader click on "shift busyness".......

:eek: GM site too......So "Lot they know" is a under statement....News travels SLOOOOW in there world.....


MAC :D

On Edit ,some have gotten it installed under warranty repair.One member (?) paid $160 something bucks for the dealer to install.....Good luck......

[ 08-29-2002: Message edited by: mackin ]</p>

[Kennedy]

The actual hookup at the TCM should only take 15-20 minutes.

I used a 12" loop (terminals pre-installed on both ends) that I got from SteveO (yes he is still around) and added a 2 pin weatherpack connection to make servicing easy. Still haven't mounted the actual switch.

[chipper]

Asked my dealer about it yesterday & he said yes they had installed 2, but both owners reported a loss of about 1 1/2 MPG on fuel economy, sooo, I passed.

[madmax7]

I'm getting my 5th gear lockout installed by the dealer tomorrow.

Jeff, I see you are in AZ also. I am getting it at Chapman Chevrolet in Chandler.

email me for details if you would like.
jmedhurst@aztechcontrols.com

As far as the mileage goes, if you constantly run in 4th gear rather than fifth, of course your gas mileage will suffer. If you need to lock 5th out you are probably towing and getting sucky mileage anyways. I want it for climbing hills. The Allison wants to shift to 5th, my rpm's drop, more throttle is applied, and egt's start to soar. I drop into fourth, and egt's come down (less throttle required, I think).

I may be wrong as to the reason why theis phenomena exists, but I know this does happen (egt gauge on manifold, pre turbo)

Just my 2 cents. :D

[Jeffrey Shaffer]

It sounds like its easy enough to do myself where is the tcm located at? Thanks

[odoh]

Mackin ~ Looked for the TAC article you specified but not shown. Could you chk & provide the specific link? Thanks ~ odoh

[SoMnDMAX]

http://service.gm.com/techlink/html_en/pdf/200207-en.pdf#dst13

The above link is for the specific page. You will need Adobe Acrobat to read the tech article.

The TCM is located on the drivers side rear or the fan shroud.

[More Power]

Moved to "2500HD/3500 Trucks & Drivetrains"

[Bobcat698]

Then You have us lucky 2003 owners who have a nicer switch than you "older make" truck owners tongue.gif ;)

We get a more attractive switch built right into the end of the shifter :rolleyes: :D :cool: tongue.gif

Garrett :eek: :eek:

[Bobcat698]

There is a picture of it here also:
http://imagehost.auctionwatch.com/bin/imageserver.x/00000000/omycarz/10611511.jpg

Plus, we get a CUTE :rolleyes: :rolleyes: little picture of a trailer instead of Tow/Haul :eek: tongue.gif

[dave p]

i would like to have mine done also. can any one tell me a dealer in michigan that has done it? i really want the lock out. would appreciate any advice? dave p :cool: :cool:

[ronald pasquetti]

the term allison uses is overdrive disable . since od is 5th gear when this input is activated and the selector is in od( or 5th ) position the highest available is 4th range
it is simply an input to the tcm .

[Mic]

dave p

I got mine done this past week end...took at but about 3 hrs. That is with a few barley soda breaks... tongue.gif

Only difficult part is the routing of the wires...I was quite particular and neat about it.

If you ever make it over to the Detroit area give me a hollar and I can show you... smile.gif

[ 09-04-2002: Message edited by: Mic ]</p>

[dave p]

thanks for your response mic. i am in battle creek,
pulsiphe@voyager.net. would like to get overdrive lock out, installed. has any one in michigan had a dealer retro fit a over drive lock out? thank dave p :cool:

[SC2222]

I also would like to have the 5th gear disable switch installed. Does anyone know of a dealer in northern Calif. that has installed the switches? I pull a heavy 5th wheel and being able to cut out 5th gear would be a great help.
Thanks

[GMC D-Max]

Here's a question: Anybody know if it would be possible to retrofit the '01-'02 trucks with the new, shifter mounted switch (and related wiring plus TCM update) and get the OD lockout?

[ndamico]

I've installed the high-idle and OD lockout in my truck. I ordered some nice switches which should be here today or tomorrow. I live in Sacramento and would be willing to install yours. I have extra TCM/ECM pins and should have enough switches. One of the other DP members checked with my local dealer and they said they didn't have time to install the switch as they were so booked with warranty work. drop me a note at nick@wackywack.com if you would like some help with it.

[TBC]

I had my truck in for a lopey idle and to have the updates including the 5th gear lockout. The dealer said that update has been replaced with a new update without the switch. (old update was ver 3.5 dated 3/20/02) I don't know what the changes are yet in towing but the truck has a different personality (Hoot's words) than before. The trans is smoother shifting and the shift points are a little different. One big difference is the power from start to turbo kickin. It is much smoother and stronger than before. It has more low end power. I like it. The service rep hinted that if it was not OK that they would fix it and I believe he was saying the lockout. I am towing to Amarillo this weekend so I will know soon if it changed anything.

[CntrlCalDmax]

I installed the OD lock-out and high idle this weekend using a single on*center-off*momentary double pole switch for both features. Since you can't use both at the same time, it works great and I had one less switch to install somewhere.

[TBC]

CntrlCalDmax

Did you have any of the updates done before installing the lockout switch? If the truck doesn't perform well on my next tow I will push the dealer to do the install under warranty but if not I will do it myself. It doesn't appear to be a real problem doing it. Thanks.

Tom

[CntrlCalDmax]

Tom

Yes, I had the TCM updates done about 2 months ago. Getting to the TCM to install the wires was the hardest part, maybe because I had the PCM loose and kind of in the way for the high idle at the same time. Over all it is stright forward and not to difficult.

Leo

[c5dura]

My truck was built on 5/10/2002. Does that mean my TCM already has TIS 2000 version 3.50 so that all I need to do is add the wires and switch?

On a side note, I just had my whole PCM replaced yesterday at the dealer (P1683 codes galore), and I showed them the TAC talking about the TCM upgrade and they never heard of a 'TCM' module but assured me the new PCM 'had all the latest features'.

Do I need to go back to them before installing the wiring in order for the OD lockout to work?

[odoh]

My dealer doesn't want to as he's too busy w/defiencies and another dealer didn't even know what I was talking about. ~ odoh

[mdrag]

OD lockout/LED indicator installed last night. It is easier than doing the high idle install since the TCM and connectors are easier to see and reach as compared to the ECM.

Removing the clear plastic cover over the terminals made installing the added terminals much easier. I was going to run all four wires from the TCM connector (2 for the OD lockout, and 2 for the LED indicator), however the TCM suppied 12V ignition power terminal at J1-2 was already occupied with a pinkish color wire, so I used another ignition switched 12V source inside the cab.

A momemtary n.o. switch and LED (with attached resistor) from the Shack - less than $5, plus a few $ of wire. Save yourself at least $100 -$200 and do it yourself.

Works as advertised... :D

[mdrag]

c5dura,

It is my understanding that the TCM update is independent of the ECM update. It is the same process as an ECM update - but it is done separately. Not really confidence inspiring if the service personel do not know that the TCM exists... :(

I meant to add that I could NOT find the TCM connector pin outs in the 2001 Helm's manuals...other than the TCM's location, there is very little info in the manuals on the TCM :confused:

mdrag

[ 09-21-2002: Message edited by: mdrag ]</p>

[mdrag]

A few pics of the revised OD lockout switch (the RED square switch 4th from the LEFT) and BLUE LED indicator. After seeing ndamico's switches, I was not happy with my Shack stuff :(

http://community.webshots.com/user/mmdrag and check out the Cupholder Switch album

Nick,

Thanks for the info on the switches.

mdrag

[hoot]

nick and mdrag,

Is it possible to post the switch info? Where to buy?

Thanks

[big dipper]

A qutoe from GMC DMAX:
"Here's a question: Anybody know if it would be possible to retrofit the '01-'02 trucks with the new, shifter mounted switch (and related wiring plus TCM update) and get the OD lockout?"

Is it possible? I am curious of this as well?

[mdrag]

hoot,

I got mine at www.mouser.com. Also at www.digikey.com I've used both vendors before and both are GREAT. I went with Mouser since they offer the switches in component form - that is you could order the switch, LED or 12V bulb, and lens cover. I ordered a few different lens and LEDs since I was not sure what color I wanted.

Here is the catalog page link for Mouser:

www.mouser.com//index.cfm?handler=fra_pdfset&dir=612&pdffile=596

NKK makes this switch in round, square, or rectangular shapes. Very nice feel to the switch. I'm using the square bushing mount with the RED LED and RED lens. If you decide on using an LED to light the switch (versus a bulb), a resistor must be wired in parellel (either the anode or cathode side, does not matter). I used a 2.2K ohm resistor. The RED LED has a very nice red glow to it. I tried GREEN and AMBER as well, but liked the red.

mdrag

[mdrag]

I also found this site for NKK switch info - schematics, proper LED placement in the switch etc. The switch body has a very very small (+) and (-) on the terminal end, and the LED has a flat spot on the base of the LED to denote the (-) leg. This may vary depending on the LED model# used.

http://us.switchzone.com/Products.asp

If the forum edits the link, the last three letters are-&gt; a s p

I used the KB series switch (smaller).

mdrag

[letsgo]

When using light emitting diodes (LED) be aware that they have a variety of maximum current draw, eg. one might be 0.005amps (5ma) another could be 0,020amps (20ma) , to limit the current through the diode you must put a resistor in series with the diode (current limiting resistor). other wise "poof

NOTE the use of a 10,000 ohm resistor (recommended by GM) for the overdrive lockout would indicate that the maximum circuit loading is 0.0015 amps or (1.5ma)

NOTE the following is for other light indication applications, since the charging voltage in the Duramax is aprox. 14.6 volts.

recommended resistors are resistor = voltage divided by milli amps.

14.6 / 0.005 = 2900 ohms or larger

14.6 / 0.02 = 730 ohms or larger

larger is better smaller will cause the LED to burn out, LED polarity is critical.

also what is the max. current draw of the circuit you are hooking into?????????

good luck

[ 10-21-2002: Message edited by: letsgo ]</p>

[hoot]

Isn't the lockout a momentary switch? How does it wire so it stays on?

[letsgo]

when the chip sees a pulse to ground it has a laching circuit that turns on electronically, the next pulse it sees the latching circuit turns off electronically.

good luck

[mdrag]

hoot,

If you are asking about the LED built into the momentary switch, I have it wired to a switched 12V source so that the LED is illuminated all the time the ignition is on, or independent of switch position - hence the BLUE LED indicator at the rear of the console. The BLUE LED turns on/off when you cycle the momentarty switch.

You could wire the switch LED so that it only illuminates when the switch is cycled (dependent) and the OD lockout is active, then the BLUE indicator LED would not be needed.

I decided to do it this way to keep consistency with my other switches - all of the rocker switches have (1) independent pilot light and (1) dependent pilot light, except for the far right rocker switch, it has (1) independent pilot light.

mdrag

[hoot]

Thanks guys... got it.

I just needed to read the article. See sig.

[dave p]

i have the lock out and it makes towing much better no shifting up and down. transmission temp is cooler also. milage seems to be the same so far. dave p :cool:

[Wesley Briggman]

SC2222,

I had the lock-out switch installed by Mataga GMC
some months ago. They charged me $166.93. It works fine. We just returned from a 2,000 mile road trip and found the feature very beneficial while climbing and descending hilly and curvy mountain roads. My only complaint is that the LED they used is not bright enough to see during the daytime.

I try to deal with Jim Watson, Service Advisor.

Send me an email at "wbriggma@pacbell.net" with your phone number and I'll give you a call to discuss the details.

[GW208]

Maybe I missed this in all the previous posts on this subject but, if I have the TCM on my 2002 GMC D/A (built 4/02) reflashed for the 5th gear lockout will the "tow/haul" mode still function the same as it does now?
Al

[Wesley Briggman]

GW,
Yes, the tow-haul mode is the same.

However, the software (flash?) update that allows the OD lock-out to be installed changes the characteristics of the transmission by reducing the shift-busyness between 4th - 5th while climbing or on curvy mountain roads. The update also allows you to use throttle in OD without premature down-shifting.

The OD lock-out button allows you to force a down-shift to 4th gear from 5th or if in 4th to prevent up-shifting to 5th. Here again, I use it in the mountains to prevent shift-business.

I am glad I had it installed.

Hope this helps - Wes

[scduramax]

I was looking at Allison's website learning about the 06 six speed allison and I thought I would look at 05 and previous allisons. On the third page it talks about how to disable overdrive (fifth gear). It says to hold in the tow/haul button until it flashes on the instrument panel. I did't know if this works or if anyone else knew about this?