I want a 4wd Bravada

[bravad'oh]

Hi all. I just bought a 2002 Bravada with 100k on it. The front axle coupler splines are stripped off as well as that end of the intermediate shaft. I have already purchased a used disconnect and shaft to install. I don't want full time AWD so I think if I can just add my own switch for the front axle disconnect I can turn it on and off when I want to. I did see a post on Trailvoy where a guy said he did it but I can't find any more info. From what I gather so far, I would have to send + or - voltage to the actuator to tell it what to do. Is that going to be +5v and -5v? If so where can I get that?

P.S. Love this site and lots of great info!

 

[CdnGMan]

Hey mate...
Welcome aboard!!!
Always good seeing another Southern Ontario Canuck in our midst...

We're having a meet up in Barrie / Midland on the 29th if you're up to meeting a few of the peeps from the GTA...
Check out the link in my signature for more details... if you're interested of course.

 

[Wooluf1952]

Can't help on the conversion, but,

Welcome

In case you haven't heard:
http://gmtnation.com/f5/welcome-gmtnation-com-heres-story-226/

 

[bravad'oh]

Hey mate...
Welcome aboard!!!
Always good seeing another Southern Ontario Canuck in our midst...

We're having a meet up in Barrie / Midland on the 29th if you're up to meeting a few of the peeps from the GTA...
Check out the link in my signature for more details... if you're interested of course.

Thanks for the invite. Sounds like fun.

 

[The_Roadie]

Interesting project. Did you get the connector for the front axle actuator to make the connection easier?

In my master thread on the OS about the actuator's theory of operation, I posted:

There's a 4-wire harness on the right side. It needs +12 and ground. The control signal from the TCCM goes high to command the actuator to extend its probe for 4WD, and goes low to command retraction for 2WD. There is a feedback signal that confirms to the TCCM that the actuator is working, and it sends a low for extended and a high for retracted. Upon first use, the TCCM senses the feedback signal, and if the actuator doesn't succeed in changing state when it's commanded to, the TCCM gives up, starts blinking one of the control switch LEDs, and (importantly) gives up. It won't try again until you turn the car's power off and reset the system. So if the actuator ever fails once to go to the position it's told to, the TCCM stops trying. It's not a serial data bus kind of module like the door switches or HVAC control box.

So you need to give the actuator a fused 12V on pin D, ground on pin B, High on pin A to command 4WD (and low (ground) for 2WD), and you can ignore pin C because your TCCM doesn't look for a status signal. I don't actually remember at this point if "high" in my description is +5 or +12V, but I could check sometime. If you need +5, the TCCM should be putting it out on connector C2, pin B8. I can post a picture of the connector if you don't find it in the available manuals. http://gmtnation.com/f23/need-service-manuals-get-them-here-371/

Only fly in the ointment is that without a NP226-programmed TCCM, you're going to get NP126 behavior, which is 5% torque being sent forward all the time, increasing as the TCCM detects wheel slippage. There will be no way to command full-up 4WD behavior with that system, so your biggest benefit might only be in keeping it in 2WD mode for more predictability on variable-traction surfaces.

 

[bravad'oh]

Interesting project. Did you get the connector for the front axle actuator to make the connection easier?

Yes

http://gmtnation.com/f23/need-service-manuals-get-them-here-371/[/url]

I did read that post and that is what got me thinking about +5/-5v. I know some electronics do communicate that way. Thanks for pointing me to the manuals. I got some more readin' to do. You guys should stick that link right in your welcome letter.

What I really want is control over AWD/2WD. My TCCM seems to quite happy actually not accomplishing anything. I will just leave it alone and when I want the extra traction I will turn on the front axle.

Thanks for the help and I will let you know how it works out.

 

[bravad'oh]

Well, I did a little bench test and I am surprised how simple the actuator is. I connected 12v to pin D and ground to pin B. Nothing happens(not suprising, just powering up the circuitry inside) Pin C, which connects to Axle Switch Signal at the TCCM, shows open. No ground, no power. Connect 12v to pin A and then the actuator moves the plunger to the engaged position. Pin C gives a ground, which is good for me cuz I can use it to turn on a light signaling engagement. As long as 12V remains at pin A the actuator stays in the engaged position. If I remove all the power at once or just the ground the actuator stays in engaged, which could explain why some trucks get stuck in 4wd. When power is removed from pin A only the actuator returns to the disconnect position and pin C goes back to open. This is probably not news to alot of you but it showed me that this is alot less complicated than I thought. Instead of using an expensive Tech tool to get the TCCM to shift the disconnect you can just go right to the actuator and do it yourself.

 

[bravad'oh]

Hey mate...
Welcome aboard!!!
Always good seeing another Southern Ontario Canuck in our midst...

We're having a meet up in Barrie / Midland on the 29th if you're up to meeting a few of the peeps from the GTA...
Check out the link in my signature for more details... if you're interested of course.

I was seriously thinking about joining you folks on Saturday but I could not work it out. Please keep me in the loop for any future get togethers.

 

[CdnGMan]

I was seriously thinking about joining you folks on Saturday but I could not work it out. Please keep me in the loop for any future get togethers.

No worries... while it was fun, the rain made it that much more interesting...
As for the date of the next meet, check out the link in my sig - that's where we tend to post up the info...

When I'm in PP next, I'll keep my eyes open for you tho...

 

[bravad'oh]

I have refurbed my new disconnect, added a grease fitting, and installed it yesterday. I used broken acuator stuck in the connected position to test my AWD system and it performs as it should. That is a relief since I did not want to have to fool with a sleeping TCM. I am curious as to how I can get my transfer case to give me actual 4wd, but first I need to get my wiring set up for my disconnect. 4WD light indicator on the dash would be cool as well.

 

[bravad'oh]

Well, I did a little bench test and I am surprised how simple the actuator is. I connected 12v to pin D and ground to pin B. Nothing happens(not suprising, just powering up the circuitry inside) Pin C, which connects to Axle Switch Signal at the TCCM, shows open. No ground, no power. Connect Ground to pin A and then the actuator moves the plunger to the engaged position. Pin C gives a ground, which is good for me cuz I can use it to turn on a light signaling engagement. As long as ground remains at pin A the actuator stays in the engaged position. If I remove all the power at once or just the ground the actuator stays in engaged, which could explain why some trucks get stuck in 4wd. When ground is removed from pin A only the actuator returns to the disconnect position and pin C goes back to open. This is probably not news to alot of you but it showed me that this is alot less complicated than I thought. Instead of using an expensive Tech tool to get the TCCM to shift the disconnect you can just go right to the actuator and do it yourself.

I edited this post to make the information correct. I was using a power supply that had two black wires for connections and I did not notice that what I was thinking was the + connection was actually the negative.