UPDATE: its fixed, 550 bill...i pretty much got raped lol. bad motor, bad module, bad TC vacuum switch (which i just replaced about 3 weeks ago) but shes working now, and i trust the mechanic who fixed her

 

If he supplied those parts 550 is actually not bad, are you going to have to eat the motor you bought?

 

Encoder repair on Wife's '04 Blazer.... pictures at: www.rlfarms.com/blazer/

Blazer's 4x4 has been flakey for several years, but on the ranch in central California it never snows so, 2-hi and 4-low worked fine.... But we moved to Reno, Nv. and winter is comming (it snowed a few days ago at Lake Tahoe, so it's comming here in a couple of months). Reading through the GM shop manual, only 2-hi and 4-low IS a FAILURE mode the TCCM (transfer case control module) goes into when it can't properly "read" the encoder signals. To see DTCs (diagnostic trouble codes) for the 4x4 system, ground pin 13 of the ALDL (assembly line data link) connector (under the dash near the steering column), turn ignition key to "on", observe the DTCs on the 4x4 push button's LEDs. Hers had a DTC of 002 (bad encoder or connections). I've cleared the codes before (by unplugging the TCCM for a while so the capacitors could discharge) and it would shift fine for several shifts, then revert to only 2-hi and 4-low again. So, time to fix it (before it snows). I unplugged the connector from the encoder/motor and checked the "channels" with a voltmeter (turn ign key to "on" and measure the channel pins to ground, should be 5.0 volts +/- 0.4) OK. I removed the Encoder / Motor assembly (after removing the front driveshaft), and took the unit into the operating room (aka the kitchen table). I removed the three security torx screws and seperated the encoder from the motor / gear assembly. SEALED.....DANG.... so I tested the Encoder "switch" for channel "A"... WOW, while SLOWLY rotating the encoder, the ohmmeter jumped from 0.9 ohms to 40.0 ohms to 300.0 ohms (very flakey), then open, then back to ground at the other end of travel. I figured if one channel is bad, odds are the other channels are bad too. Well, it's only core value now, so nothing ventured....... I took my pin vise with a SMALL drill bit and drilled two SMALL holes just on the inside of the "O" ring (see web pics). Introduced some contact cleaner into the switch assembly with a syringe (the wife is a nurse, she gives me some very handy tools!!!). I rotated the encoder "switch" through its range of travel several times (like 30) and retested the "channel" pins to the ground pin. Very low resistance and steady, either ground or open for A, B and C, depending upon position, no more high resistance. Channel P is a "pulse" to ground while the encoder is rotating. Reattached the encoder to the motor assembly and reinstalled it into the truck. Cleared the DTC by unplugging the TCCM for several minutes. Tested the truck on and offroad, shifted just fine!!!! many many times... FIXED, at least for now... Later I thought that I should have put a drop of silicone seal or black tape over the holes....... oh well.....

 

ya i was able to get a return on the other motor hopefully it get back to the guy before my 14 day turn around lol (fingers crossed). i know the Stealership probably would have charged me like 900 so im ok with what i paid and piece of mind going down the road, besides i trust the guy who worked on her. i have been going to him for about 7 yrs now and he always treats me well

 

i think your problem may have been different from mine, since my TCCM and motor was bad. im not sure if there is any repair on the modules since im told they are solid state. if there is its way out of my experience level to deal with lol

 

I was an electronics tech 1st, and an almond farmer 2nd (now retired)... Years ago I opened up the TCCM box and looked at the circuit board... A lot of surface mounted componants (requires special soldering equipment), plus it has a conformal coating on it, and since you could never get a schematic diagram or a board layout for that module anyway, I figured it is not really "field" serviceable. As far as the Encoder Motor goes, my motor worked fine, just the encoder part was messed up..... The $200.00 factory shop manual is invaluable from an electronic servicing standpoint.... Glad you got yours fixed....

 

lol i kinda wish i kept my old motor cause it would have given me something to explore and possibly learn about and maybe fix and would have saved me about 90 dollars off my bill..lol oh well. glad to have you hear im gonna come to you for electronic problem in the future lol

 

Back on the ranch the motto was Don't throw anything away, you never know what you may need it for in the future.... after 22 years all that saved junk was worth several thousand $$$$ at the scrap yard...... always willing to give logical advice.....

randy@RLFARMS.com