4wd system operation 98up Blazers

[jackwfire]

Good Morning,

Just purchased a 2001 Blazer S10, 41,500 miles. Been reviewing your forum and it looks like this site is going to be invaluable to me in the months to come.
Thanks to all for posting this information.

One question, at what mileage do ball joints start to go ?

Thank you,
Jack

[lancescott67]

In my experience, ball joints start to fail on average at about 70,000 to 80,000 miles, but thats here in Minnesota with rough roads all winter long, and pot holes up the ying-yang all summer! The better drivers get about 120,000 or more out of them. Be sure to keep an eye on the control arm bushings as well, not sure if they have improved them over the older models, but they are a common failure as well.

[jb-ihm]

Quick question.....My 4hi and lo actually engage, but, the light still blinks in both positions. I have confirmed that they engage and work well. The only other caviat to that is that if in Auto4wd, it will switch back to 2wd. But, again, switching to 4hi engages 4wd and it stays there. It just continues to blink. Could this be a bad switch that needs to be replaced with one from motormite? Thanks

[Leifmb]

Hello, I have an 04 Blazer with NP8. There is something wrong with the transfer case shifting (every Blazer I get has something wrong with that system!). I've narrowed the problem down to either the TTCM or the Encoder Motor assy. However, the Encoder Motor works it just doen't seem to shift the TC all the way into gears. As soon as I press the Auto 4WD from 2Hi the Service 4WD light comes on but the system seems to work. However SOMETIMES after changing out of 2Hi and back the drivetrain will be in Neutral or pop into Neutral (happened while driving). I suspect the encoder motor's POSITION SENSOR is the problem. Does anyone have the pinout of the position sensor so I can check it with a meter for proper operation before I drop $$ for a new Encoder Motor Assy? Does anyone know where I can buy the Encoder's Position sensor seperately from the Encoder Motor?

Thanks,
Leif

[burnchassis3]

Is my blaze throwing a code if the service 4wd light is not on?
It wont go into 4wd the light just flashes.
How much will it cost avg to hook it up to a scanner at a shop? $100.00?
Anything I can try myself ,before I go that route?
Thanks!
CS

[96_blazer_5spd]

i have a 99 with the 4 button switch, my 4x4 wont engage, and the lights wont come on on a brand new switch, could all this be because my abs light is on. oh and my service 4x4 light is not on

[offroader2000]

Originally Posted by laxman21

Here was my problem.



On 99up there is an additional vacuum switch on the firewall that switches the vacuum on and signals the TCCM also.

hey bud were abouts is it located what side firewall???

[Leifmb]

That switch is located above the distributor on the center (engine side) firewall.

[offroader2000]

Originally Posted by Leifmb

That switch is located above the distributor on the center (engine side) firewall.

call me a dope but i dont see that switch,do all 99 blazers have this mine is an electric shift tc.i followed the vac line from the actuator(under the battery tray and it leads all the way to the tranny where it does hook up to a vac switch of some kind.any thoughts?

[Leifmb]

The actuator is under the battery tray and is NOT the same as the vacuum switch located on the center of the firewall above. The vacuum switch is pretty small and has one electrical plug with two wires and two vacuum lines going to it.

[offroader2000]

Originally Posted by Leifmb

The actuator is under the battery tray and is NOT the same as the vacuum switch located on the center of the firewall above. The vacuum switch is pretty small and has one electrical plug with two wires and two vacuum lines going to it.

yes i understansd the difference between the actuator (under the battery)and the vaccuum switch u say is located center of the firewall near the distributor,problem is that i just dont see it.do u need to remove the distributor cap to see the vac switch?//?perhaps a pic might help.usually im pretty mechanically inclines but shit i just dont see it lol.

[kuhlman5]

Originally Posted by laxman21

Here was my problem.



On 99up there is an additional vacuum switch on the firewall that switches the vacuum on and signals the TCCM also.

Do you have any additional info on the part (i.e. part number, where available). I have the same problem want to get fixed ASAP. Any help greatly apprecaited.

[Leifmb]

12577412 is the part number for the Transfer Case Control Module (TCCM). I changed that and all my problems were fixed. Same part failed on two different blazers of mine- 1st a 2000 and then a 2004.

[JoulesWinfield]

Only one problem with the technical description.
"Note that if 4 Hi selected no action done in the transfer case."
Not true. The front drive shaft is always connected to the front left tire. Not the x-fer case. When 4-Hi is selected the transfer case is engaged and there is a ball plunger actuated vacuum switch that sends vacuum to the diff actuator. That diff actuator (located under the battery) is what draws the collar inside the front axle to couple the differental to the front right tire.

This is a common misconecption and misrepresentation in the GM tech documents.

[s10blazerman4x4]

Still not seeing this vacuum switch that is on the 99s and up, Anyone have a picture? Above my distributor cap there is nothing but red paint and a fancy sticker from the General.