Well, 'tis the season for the AWD in my Bravada to go flaky...

Last year, when my AWD went out, the mech tracked down the issue as a bad TCCM, and replaced it with a used one. Once again, the AWD won't engage, so I'm gonna start by swappng out the TCCM (encoder motor is new) again.

My question is, once I swap the units out, is there anything else that needs to be done - codes erased or some such? As always, thank you for the info!

 

dont swap it just yet. look at other things that might be much cheaper to fix.

which system do you have?

my awd wasnt working either........i started spending money on parts, new encoder motor, new tccm and new dash swtich and it still did not work.

turned out it was just broken vacuum hose under the hood by the firewall, a repair that costed me $6 (if you dont count the other $350 I spent on the parts i didnt really need).

give us some symptons of what the system is doing (or not doing).

 

Well, it's the Smartrak system, so there are no dash switches, it's all automatic. As far as the symptoms go, the front wheels are not engaging when the rear wheels slip. I've checked out all the vacuum hoses I could find, but I'm certainly open to suggestions regarding ones I may have missed.

 

pfffffff goes to show how much I know.

if the front wheels on bravada are engaged the same way as they do on the blazer, then you want to remove your battery and tray and inspect the air balloon located under the tray. makesure it has no rips or holes in it. makesure there is vacuum in the hose going to the balloon.

 

Please take Tinteds advise, mine was a hole in the line up by the firewall also but it only cost me 250 before i found it.

 

In another thread here, I found a vacuum schematic for the s-10 blazer. Can anyone verify if the Bravada (Smartrak) uses the same system?

 

An AWD Bravada front axle is always engaged. As such, there is no vacuum actuated components for the 4wd system. The vacuum supply will still run from the same fitting as the PCV hose, to a check valve which splits to the vacuum reservoir (inside the driver side fender) as well as into the firewall for the HVAC system.

As far as your problem, if the TCCM is the problem, then replacing it should fix it. You may want to resistance test all of the wiring to/from the TCCM & encoder motor just to be sure.

I recently diagnosed & repaired a friends 2000 Bravada AWD and the problem was a faulty encoder motor. The motor windings were shorting out. It would attempt to move, but wouldn't get very far before the resistance would shoot up. It was fairly easy to diagnose having my AutoEnginuity scantool to engage & disengage the transfer case, but without a scantool capable of such tasks, it can be difficult.

 

Ok, I had the codes pulled, and there are no relevant codes showing up. Does the lack of codes mean I can rule out the TCCM? I know when the TCCM failed before on this vehicle, it was throwing a C0308. Will a bad encoder motor cause a code? The Encoder motor is about a year old, but I know that it having failed is not out of the realm of possibility? As always, thanks!

 

Culprit turned out to be the less-than-a-year-old encoder motor. Fortunate for me, as there wasn't a junkyard TCCM to be found, and I happenned to have a take-off encoder laying in my garage.

In my junkyard search, I came across several Bravada TCCMs with a single orange connector, as opposed to the large green and small black ones on mine. Is this for a different setup? I thought all Smartrak systems were the same...