'00 Won't Shift Into 4-Low

Hello,

Just bought a pristine looking 2000 Chevy Blazer. Looks showroom new.

Aside from a weak lock motor on the driver's door, a power mirror switch that needs replaced, and a CD player that doesn't play CDs, it works very well...

But the 4 Low will not work.

I have 2-hi, 4-hi auto, and 4-hi, but no 4 lo. It tries to shift - there is a definite "thunk" from the transfer case - but the light stays flashing and goes back to whatever mode it was in before. Just a quick shift in and shift out, I guess.

When I shift, I am in neutral and I have tried it with my foot both on and off the brake.

Any help?

Thanks,

Josh <><

Hello,

Just bought a pristine looking 2000 Chevy Blazer. Looks showroom new.

Aside from a weak lock motor on the driver's door, a power mirror switch that needs replaced, and a CD player that doesn't play CDs, it works very well...

But the 4 Low will not work.

I have 2-hi, 4-hi auto, and 4-hi, but no 4 lo. It tries to shift - there is a definite "thunk" from the transfer case - but the light stays flashing and goes back to whatever mode it was in before. Just a quick shift in and shift out, I guess.

When I shift, I am in neutral and I have tried it with my foot both on and off the brake.

Any help?

Thanks,

Josh <><

You need to get it on a transfer case capable scanner and d the shift test and read out transfer case codes.
Post back any codes/code no.

Yeah, I was thinking along those same lines.

I just went out to see if I could "paperclip" the TCCM codes on this OBDII system, but it looks like I only have chassis ground, signal ground, bus, and battery power.

I've had OBDII scanners in the past but don't remember them ever being TCCM capable. I doubt Autozone carries them - was hoping to get this done tonight or tomorrow.

Where do you recommend I get this scan tool?

I removed the battery today for charging, and I foolishly checked only the 4hi for function before I bought it. I do not know if it worked before. I unhooked the battery and am hoping that perhaps this will do it.

Anyway, about that TCCM scanner..?

Thanks,

Josh <><

P.S. Had a Bravada for a number of years, so I don't necessarily need 4-low. Would just be nice to have the option, and to have everything working. Thanks again, J.S.

My truck does the same thing. I also cannot get the transfer case to shift into neutral, have you checked that as well? I believe either my shift motor is bad or the shifting mechanism in the transfer case is frozen due to lack of use. These trucks that have "auto" 4WD have the front driveshaft spinning all the time anyways so it is easy enough to still have 4WD even if the transfer case does not shift since nothing actually shifts when you lock it into "auto" or "4HI".

Hello,

No, I do not have neutral either.

I'll find someone to pull the codes or find a code puller, and report back.

Josh <><

Hello,

No, I do not have neutral either.

I'll find someone to pull the codes or find a code puller, and report back.

Josh <><

Sorry.
Auto Zone and or paper clip or code readers or battery disconnect does not work on the auto 4W transfer case.

You need a high end full manf. spefic capable scanner that will read out and test all engine /transmission/transfer case/abs computers.


High end Snapon or GM tech scanners will test them for you.

If any ABS or tarnsmission /engine/transfer case codes post back code no.
Best to find a good repair shop that has one.

I will put the TECH2 scanner on my truck this week and see what it says. I have honestly not cared since I have little use for "4LO" or "Neutral" so I haven't even thought to test/scan my truck. I wll post back with my results in case it will help you fix your truck.

(I still say the transfer case itself is gonna be the issue. I am still betting the shaft that goes from the shifter motor to the shifting mechanism in the transfer case is frozen due to lack of use).

But it moves - that's the thing. I'm betting on a switch. :D

Not to discourage you, my shift motor makes noise as well like it is doing something. THis is the one thing that really makes me not like 4WD without a good ole fashion pull lever....

Not to discourage you, my shift motor makes noise as well like it is doing something. THis is the one thing that really makes me not like 4WD without a good ole fashion pull lever....

The biggest problem is that I do not have 4-lo. It will try to shift, and I'll even hear the transfer case shift, but it will shift right back out. The bypass for this does not work, so I'll have to get familiar with this style - I usually do not like push button 4 wheel drive for this exact reason. - Me, here: http://www.familyfriendsfirearms.com/forum/showthread.php?t=87460

We think alike :D

Wish I had pin 13. Make this a whole lot easier.

As I understand the transfer case and its shift motor, there are internal sensors as well. As soon as the case says that it's in 4wd, it activates the motor which engages the front wheels.

I've not been able to get my hands on schematics though - nothing online that I can find, and def nothing in the Haynes Manuals at Autozone. Napa is of course closed today, so no Chilton manuals available.

So all this is best-guess conjecture. Dad was a GM engineer before being forced into retirement due to the economy, and I've been chewing his ear off ever since I got the thing - and we both hate phones! :uhoh:

Cold and rainy today or I'd be under the beast checking fluids.

Thanks very much for your help.

Josh <><

Well folks, local dealership doesn't have a TechII scanner. Gonna have to drive about 45mins east to find one.

But an update: It snowed a bit today with ice patches, so on the way to work I ran 4wd on demand. I pulled up to a stop sign and decided to try 4lo just for the heck of it.

It went into 4lo, but wouldn't shift back out!

Was fun finishing the commute at 10mph and hitting every gravel patch I could find.

After work (only there for a couple hours today to cover a partial shift due to a call off), I went out, hit 2wd, and it thunked back into 2wd!

So I don't believe the shift motor is dead, but it's def weak. Front axle engages just fine, no probs there.

Any thoughts besides 1) the TC shift motor and 2) needing to get the codes?

Thanks,

Josh <><

I'd wait for MT-2500's response first, but I'd say you really need to have it scanned first just to be certain. You are braver than me, I don't hit the "4LO" button just for this very reason, LOL!

Well folks, local dealership doesn't have a TechII scanner. Gonna have to drive about 45mins east to find one.

But an update: It snowed a bit today with ice patches, so on the way to work I ran 4wd on demand. I pulled up to a stop sign and decided to try 4lo just for the heck of it.

It went into 4lo, but wouldn't shift back out!

Was fun finishing the commute at 10mph and hitting every gravel patch I could find.

After work (only there for a couple hours today to cover a partial shift due to a call off), I went out, hit 2wd, and it thunked back into 2wd!

So I don't believe the shift motor is dead, but it's def weak. Front axle engages just fine, no probs there.

Any thoughts besides 1) the TC shift motor and 2) needing to get the codes?

Thanks,

Josh <><
It is not safe to operate it on dry payment in reg 4W.

Very strange your dealership does not have one.
All GM dealer service departments are required to have all tools and diagnostic equipment to repair GM stuff.
But not all dealerships have factory trained techs.
If not ask for your money back and find one that does.

It is your choice but I wolld just find a good local repair shop that has the equipment and know how to test and fix it.

For repair info and wiring diagrams you will need a factory repair manual or a All Data on line sub.
http://www.alldata.com/products/diy/index.html
Some public libarys also have auto repair info.

It is not safe to operate it on dry payment in reg 4W.

Very strange your dealership does not have one.
All GM dealer service departments are required to have all tools and diagnostic equipment to repair GM stuff.
But not all dealerships have factory trained techs.
If not ask for your money back and find one that does.

It is your choice but I wolld just find a good local repair shop that has the equipment and know how to test and fix it.

For repair info and wiring diagrams you will need a factory repair manual or a All Data on line sub.
http://www.alldata.com/products/diy/index.html
Some public libarys also have auto repair info.


Hello,

I know about the 4x4 lock not being good on the transfer case. So I disengaged the front axle when it stuck ;) No biggie. Just ran in 2 low for a bit - I modified my CJ to do this when I had it, and pretty much the same principle. Just not full floating axle on the Blazer.

I've got a Chilton on the way. Had to order it; no way I was going to try to mess with this thing using a Haynes from Autozone :rolleyes:

I thought the dealership not having one was a bit strange as well, but I also thing they're getting ready to go out of business. They're def running with a skeleton crew, and one other GM dealership already went out. :shakehead

Thank you,

Josh <><