AWD Transfer Cases

• • 90-98 used a Borg-Warner 4472 full time AWD transfer case, uses regular ATF.  The BW4472 is a single speed, chain drive, two-piece aluminum cased, viscous clutch type transfer case.  It's engaged all of the time, no exceptions and can not be disabled.  20-25lbft to turn a viscous clutch, too loose and it will slip, if it's seized it will create binding/wheelhop. 1990-1995 and the 1996-1998 use a different size transmission flange.  Chain (1.75" Wide) 43 Links (1 Blue Link) - HV033

  • 99-05 uses the New Venture Gear NV136, uses AutoTrak2 fluid, is a single speed, clutched, electronically controlled transfer case.  It's engaged by the encoder motor only when the computer detects slip.  Can be disabled by removing the Automatic Transfer Case 20amp fuse in the under hood convenience center.  Uses ONLY AutoTrak2 fluid!  You can also install the Borg-Warner case in place of New Venture case, you would just need to grab the front and rear propeller/drive shafts that fit the Borg-Warner case. Chain (1.00" Wide) 49 Links - HV062

If you are having low speed binding/chirping/shutter/etc, a common cause is using the wrong or contaminated fluid.  First check tires for even wear and pressure, rotate/swap tires around.  Second step is to replace the fluid with AT2, then do a bunch of figure 8s, put 50-100miles on it, and then replace the fluid again with AT2.  Note that the clutch packs can hold the old fluid for several hundred miles.

If changing the fluid doesn't help, and you are still getting binding/chirping then first remove the ATC(TCCM) fuse located in the under hood convenience center.  If that doesn't help, remove the encoder motor.  If removing the encoder motor still doesn't correct the problem, then the transfer case clutch pack has to be re-shimmed.

99-05 encoder motor:  http://amzn.to/2tV0Y3K  Rectangular Plug w/2 Pins, Fits New Venture Gear 136/236/246, RPO Code NP4 (All Wheel Drive Transfer Case) Torque to 15ftlbs.

99-05 Transfer case actuator(encoder motor)insulator https://amzn.to/2qQdmmq and front shaft spline seal (Shaft To Yoke)GM 12544077

The transfer case on the 99-05 vans uses just under 2 liters of AutoTrak2 fluid(it's blue in color), NOT REGULAR ATF, make sure to use the right stuff.

If you have issues with your NV136 and want to switch to the older full time BW4472 case, you will need the case and both front and rear prop/driveshafts to swap into your newer van.

Auto Trak II(AT2) Transfer Case Fluid GM 88900402 ACDeclo 773494 (used to be GM 12378508) is available at:

Prices are from the last time I looked and can change so make sure to do your research.

• • ACDeclo 773494 @ Amazon.com $6.26 ($7.45 shipping for 2) http://amzn.to/2pqU1FM

  • GM 88900402 @ Summit for $7.97($4.95 handling for 2) http://www.summitracing.com/parts/nal-88900402

  • GM 88900402 @ Amazon $12.58(Prime free ship) http://amzn.to/2owEbfu

  • ACDelco @ O'Reilley Auto Parts # 10-4017 $8.99($11.72 shipping for 2) http://www.oreillyauto.com/site/c/detai ... rd=10-4017

  • Some independent NAPA stores carry it as well, have to call to find out if they carry it. Mine sells AC 104017 $9.69 a liter.

  • AC Delco distributors will usually carry it as well, if you have any locally.

  • GMpartsDirect has the best prices but you have to order 12, other online retailers had it but the shipping cost(up to $20) was way out of line.

  • Both local dealers said they charge $8.95 a liter plus tax, but no shipping   However, when I went to buy, they only charged me $7.16 a liter.

Auto Trak II alternative:

• • • It appears that Valvoline states that their universal transfer case fluid, Valvoline Transfer Case Fluid Part # 855459(~$10 a quart) is compatible with Auto Trak II.

    • Valvoline also states that it's Valvoline Maxlife Multi-Vehicle Transmission Fluid is recommended to replace Dexron II/III/VI and Autotrak II, so could be a universal fill for our vans.

    • HOWEVER, it is red, so you would have no idea if what you were draining is regular ATF that is not Auto Trak II compatible or if it was the Valvoline.  This would also apply if it was taken in for service and they noticed that it was red they would want to change it out because of the previously mentioned binding issues.  Personally I would stick with the blue AT2, and can even be purchased cheaper than the Valvoline 855459.

C0310 Motor A/B Circuit Open 'Service AWD' light

Using a cheap bluetooth OBD reader and Car Gauge Pro on Android, it showed me the C0310 code.  I OHMed out the encoder motor and it is bad. Really easy to replace the encoder motor after removing the front propeller shaft and lower shield. I just cleaned the gasket really well and reused it. It comes off so easy if I notice a leak I will pull it and replace it. Three easy bolts and it's done, torque to 15ftlbs.  No more code or AWD light!

~$110.00 and free shipping http://amzn.to/2Efip5e