Connecting front diff to PCM

[lsv_palana]

Hello dear friends !
I have 5.3l v8 2008 hummer h3 with rear diff lock but no front. I bought front ifs from 2009 hummer h3 with front diff lock. Also i bougth new control panel from 2009 h3.
Can you tell me can i connect front diff lock to PCM as rear diff lock connected.

Temporary i connected front diff using switch that depends on 4wd low light. In other words: now i can turn on front diff lock only then 4wd low is on.

I need to connect front diff in right way (like on 2009 h3).

Please give advice... thank you.

 

[alrock]

Why do you want to connect the diff to the PCM? I'm rear diff only and it's aftermarket and not tied to the PCM. I can turn on or off at will and not be dependent on the logic that GM prescribed.

 

[lsv_palana]

I like Factory setting

 

[SGT-Wright]

I think you may need to get a PCM/BCM from a 2009 H3 alpha that came with the front and rear lockers. I believe the wire harness may need tapped into since the 2008 never had the front from the factory. As alrock said you may be better off with the diff locks under your control instead of the computer. That way you could lock up in 4HI if you are in deep snow.

 

[Bruces]

Isn't the diff locks controlled by bcm not pcm?

 

[4speedfunk]

A few owners with lockers have actually modified them to do just the opposite. They re-wire them direct so they can use them in any t-case mode. I'm not 100% positive but, I think the factory front locker is also wired to operate "downstream" of the rear one. That is...the rear locker must be engaged before the front can (so the front cannot be engaged by itself). If someone can verify this, speak up.
My front locker was added and it's on a stand-alone circuit. My factory rear locker is still wired thru the factory switch and only works in low range. I rarely use either.


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[Ordieh]

You are correct. The front locker can only be engaged if the rear is in locked mode.

 

[4speedfunk]

Ok. Thanks for confirming that. To me that is reason enough to rewire the system to full manual control. There might be times when a front locker is wanted but, not the rear.


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[lsv_palana]

As i said i create electrical scheme that works like factory and can engage front lock while 4wd low, not depend on rear locker. Have changed last right key on control panel and replace stab sys off key to it place on 2009 h3..

 

[SuperBuickGuy]

I eliminated the BCM control of the locker - in my opinion, it makes the system weaker because if it detects wheel speed greater then 30 mph; it'll shut the locker off - and that could easily cause damage.

 

[4speedfunk]

True. We must remember that GM is trying to make these features "soccer mom" proof. If you know how to drive, and you understand what a locker is...how to use it...and the dangers of using it improperly....then there is no issue. But unfortunately I think the H3 demographic is about 90% soccer moms....and 10% educated wheelers.
I deal with H3 owners daily, and I am continually amazed by the comments and situations I run across. While it can be wildly entertaining, it's also very frustrating. I have lost count of how many "hard-core" people I have surprised by telling them they do not have an AP model or lockers.


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[lsv_palana]

How you solve problem with service 4wd on display when disconnect rear locker from BCM ?

 

[SuperBuickGuy]

The computer runs a signal through the two wires - and looks for a voltage drop. I put a (iirc) 2 ohm resister between the two wires. Now the computer thinks there's something there so no light.

 

[4speedfunk]

Then run a new non-computerized circuit to control it independently?
Only downside I see to running this setup is that the Stabilatrac might fight the locker if you use it in either high range mode. In low range, the stabilitrac is defeated by the computer so lockers can be used. As long as you're aware of this, you can mimic this control and only use them in low range. I'm sure you could use them in high range but aggressive driving (wheel spin and/or drifting) would certainly induce stabilitrac and individual caliper clamping...and that might cause some issues, because the computer will try to control each wheel separately (which is not possible with the locker activated). I think that is why the factory lockers are only active in low range when stabilitrac is defeated, and visa versa.
I only use my add-on front locker in low range, just like the factory system.

 

[Panzer07]

But Don't we have this little guy to shuts off the traction control

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[4speedfunk]

Yup. That's the mystery button. Pressing shuts off Stabilitrac & holding fire five seconds shuts off traction control? Who freakin knows?
Traction control and Stabilitrac are different systems. One controls wheel spin and one controls vehicle attitude and prevents loss of control during a skid or panic maneuver. I'm sure the two are related but I'm very unsure on how they are controlled and activated. Some say both can be toggled via this button...but only on some years.
Long story short...I don't know what my computer is doing most of the time, and really don't care. I just know that GM only allows locker use in low range, and there must be a reason. So I play by those rules even though my front can be engaged at any time.

I'm proud to say I have never pressed that button, and can't imagine a situation where I would.

 

[lsv_palana]

"Drunken car" button turns off only stabilitrack. It turn it off while pressing this button 5 sec. Traction control can be turned off only by causing some issue. For me i make a switch that cut wire to brake pedal switch. Then i turn switch off - computer thinks that wire is cutted and generates traction system error. So traction turned off.

 

[lsv_palana]

 

[SuperBuickGuy]

turn traction control off when you're on slippery surfaces that don't require 4lo. 4 lo turns the stability trac off too. Why turn it off? easy, so you don't cook your brakes. If you're on low-speed, but slippery conditions the brakes will constantly apply to "maintain control" problem is the brakes heat up very quickly and really for no purpose. Another situation to turn it off is when you need tire speed - such as running deeper mud. You will spin your tires, but the brakes will try to apply to maintain traction - eventually they cook and you have to replace the pads.
Traction control is really nice when you're going to a ski resort and you want to go faster - but not when you're trying to spin through a mud-hole.

Also, your locker will unlock at 30 mph - go through my build thread, I put instructions and photos on how to wire in a resistor.

 

[Schwarttzy]

I like Factory setting

I do to.

I think the factory lock out settings are completely necessary. I have yet to run into a situation where the factory setting didn't make sense. Then I just imagine a pissed of passenger pushing the button at 70 miles an hour and causing damage that I couldn't afford. (Basically a self destruct button LOL) Also if the hummer is over 30 miles per hour, should not have a locker engaged. A locker in the snow a higher speeds makes a vehicle much harder to steer (except for torsion bias lockers) and keep on the road, along with some odd handling characteristics.