Hello-new here and very frustrated! Have a 2000 blazer that we bought from fire dept....discovered during our forst snow storm that
My 4 wd is not engaging- tried new switch panel, fuses are ok,and new control panel-nothing worked so far...What should my next step be?

 

3 button or 4 button switch on the dash? (2 different systems with 2 different diagnosis procedures.)

 

Start with the Tech Article (DIY) section, specifically the link in my signature. There are others depending on which system you have, but both have common problems. We really need to know more about what's going on and more about your truck as Chuck has already asked.

 

Thank you for the warm welcome...by reading around in the forum, we did seem to fix the 4wd...it was a vacuum hose...(4 button,btw).
Now we have another problem...This vehicle was originally owned by the fire dept- they "pimped" itup with a high amp alternator ( no, I dont know how many amps) to accomodate all the battery chargers and such....the battery keeps dying because the alternator is draining it. The answer seems simple-replace the alternator-right?
Couldnt do that as they removed all the origingal wiring,so a "normal" alternator and its wiring was not compatible with the normal alternator...so we got the original wiring harness and alternator and installed it. (prior to this,my husband was hooking it up to a battery charger every night in order to start the damn thing every morning)
Since the new alternator, it started right up-FOR ONLY 2 DAYS! UGH! Back to hooking it up to the charger at night...back to the stress of having car problems,and back to being broke because of a car!
Sooo, now the question is- do you folks think that the battery needs to be replaced? its a 5 yr battery and had it for 2 yrs.

 

To find out if the battery is bad you need to do a draw down test. Take it to an Auto Zone or such & they will check it for free I believe.

 

They can do a load test on the battery and check the alternator charging voltage and amperage output, but what you really need is a test for parasitic draw, and they don't check that.

 

Could go with a one wire alternator ( just one charging wire to the + batt term),or get the bad diodes in the one you have now replaced.