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2000 Blazer LT 4WD Problem


raymo69
12-23-2008, 05:47 AM
I have a 2000 Blazer with the 4 button 4WD system (Auto 4WD, 2HI, 4HI and 4LO). When i engage the Auto 4WD button (light on button flashed for about 5-10 seconds then stays on) and drive the truck for about 2-3 minutes, the service 4WD light comes on. When i try to shift back to 2HI i can't unless i shut the vehicle off and restart and when it shifts back there is a 'clunk' and you can feel the 4wd disengage. When i put it in 4HI or 4LO, i can feel the 4wd engage and it runs fine for about 5 mins before the service 4wd light comes on. When i put the truck in neutral and switch to 2HI (the 2HI light blinks and takes about 15-20 seconds before the light stays on) i can feel the 4wd disengage with the familiar clunk. Another thing to mention is that when the 4HI/LO is engaged and i turn left or right, it seems that something is binding (as the truck will not roll freely if i am on an incline). I had a shop scan for codes and it only came up with C0374 - General System Malfunction (doesn't tell me much).
I live in Canada and this is the first time that this has happened (recently with the amount of snow we have had) and other than winter driving i never use the 4wd (except in the spring driving around the fields on my farm).

The truck has a little over 196,000KM and matched tires.

Any help or suggestions is greatly appreciated.

Thanks

Leeann94astro
12-23-2008, 07:50 AM
Has the transfer case ever been serviced with the GM blue AutoTrak II transfer case fluid?

If not, now is the time.

MT-2500
12-23-2008, 10:21 AM
Code 374 points to front or rear speed sensor circuit or.problem.
Any other codes like 300-305?

Clear codes and watch for what comes back.

Needs to be put on a transfer case scanner for testing and checking.

MT-2500
12-23-2008, 12:35 PM
Watch front and rear wheel and or front and rear drive shaft speed sensors for reading the same.
If a repair shop scanned it they should have checked it when they had the scanner on it.

Settytb
01-06-2009, 10:10 PM
I have the same problem...It will go into 4wd...then after driving for awhile the service 4wd light comes on and you can't shift out. If you turn the car off and back on then you can go back to 2wd. Lately i noticed a grinding noise coming from either the tcase of front end. I'm not sure which but after stopping and turning it off and back on it will work fine for a little bit. I was thinking it might be a speed sensor until i heard the noise. I only tried 4lo for a minute but it seemed to work fine. I need to try it for longer. Does 4hi use the speed sensors or is that only the auto mode? I just bought this 2000 blazer 2 door 5 speed manual and this problem is annoying since i just bought it!

MT-2500
01-07-2009, 09:06 AM
I have the same problem...It will go into 4wd...then after driving for awhile the service 4wd light comes on and you can't shift out. If you turn the car off and back on then you can go back to 2wd. Lately i noticed a grinding noise coming from either the tcase of front end. I'm not sure which but after stopping and turning it off and back on it will work fine for a little bit. I was thinking it might be a speed sensor until i heard the noise. I only tried 4lo for a minute but it seemed to work fine. I need to try it for longer. Does 4hi use the speed sensors or is that only the auto mode? I just bought this 2000 blazer 2 door 5 speed manual and this problem is annoying since i just bought it!

Welcome to AF.
If you want help on yours start your own New thread.
And also research some post on same problem.
And someone will help.

raymo69
01-30-2009, 06:19 AM
I'm back and the problem is not much better (maybe even worse). I had the transfer case fluid changed and i think it already had the GM Autotrak blue fluid (since the old fluid was blue) but i changed it and added fresh Autotrak fluid (genuine stuff, bought it myself from GM dealership parts counter). I put it in 4HI and cannot get it to to back to 2HI, but it will go into Auto 4WD.
On startup all 4 buttons light up then 3 go off and only the mode that it is in stays lit.
When i try putting it into 2HI i can hear some clicking noises (and the dash/headlights dim for a second) and the 2HI button flashes a few times and then goes off and the 4HI button lights up (this happens if it is in Auto 4WD and i try to put it into 2HI. If it is in 4HI to start off then that button stays lit and the 2HI flashes then goes off). After driving for about 30 seconds then the "SERVICE 4WD" dash light comes on.

BTW, i have tried changing to 2HI when on a slight grade, the truck in neutral and that did not work.

This is becoming very frustrating and expensive (but that is the price for owning a vehicle). I may have to park/sell and take the bus.:crying:

MT-2500
01-30-2009, 08:41 AM
Back to post 3 and 4.
Needs to be put on a good transfer case capable scanner and tested out and codes ckecked.
A lot of good shift test in the scanner.
If still code 374 check wiring circuit and your speed sensors.

raymo69
01-30-2009, 01:20 PM
I am taking it to another mechanic with mentioned scanner. A new wrinkle happened today. When i started it up this afternoon none of the lights (2Hi, Auto4wd...) came on. After the truck was started both the 2HI and 4HI lights are on. I fear that this may be the begining of some very costly :2cents: repairs.:crying:

MT-2500
01-31-2009, 10:36 AM
Needs to be put on the scanner.
Post back all codes.

raymo69
02-02-2009, 07:29 AM
I tried to start the truck last night and the engine did not turn over (just clicking). There were no interior lights and the security light was not blinking and i assumed that the battery was dead. I know it is not (i assume it is not) the alternator/generator since that was replace about 1 year ago and it has been starting fine since then. This only happened since the 4WD drive issues started happening (actually, this is the first since time the battery went dead since the 4WD problem). I managed to boost and start (using a portable battery pack) and let it run for a while and it started again this morning (the battery did seem a little low on juice (it did turnover and start, but not with the same power as before). I am wondering if the 4WD problem that i am expierencing is can casue the battery to drain/lose power?:banghead:

MT-2500
02-02-2009, 08:29 AM
Improper voltage and grounds can cause all sorts of problems.
If you want it to leave home and get you back home you need to fix the battery voltage system first thing.
Before you are walking or thumbing a ride.

raymo69
02-03-2009, 05:48 AM
I took it in to the new shop and they scanned the TC and it came back with a DTC of c0300. While on the scanner we found that shifting from 4HI to Auto4WD the reading changed from 4WD to 2WD, so i assume that those buttons are still working. Next, i took off the passenger kickplate and removed the TCCM and found that there was corrosion on the connections. This was then cleanned and dielectric grease added and put back in, but the problem of shifting into 2HI was still there.
Another funny thing, the scanner also reported that the two front and the rear speed sendor had the vehicle moving at 5KM/hr while it was parked. The mechanic found it difficult to believe that all three sensor could be bad at the same time.:banghead:
Is it possible that the computer needs a firmware update?:confused:

MT-2500
02-03-2009, 08:40 AM
Was there any transfer case codes present or past.
If it is not shifting right there should be codes.
Post back the codes.
Fix check and fix the battery/charging/starter system first.
And go from there.

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