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Blazer Jimmy 4WD Questions

I just had both front bearing assembies replaced and now the ABS brakes are activating on most every stop. What can be wrong ? Also; I pulled the fuse for the ABS brakes temporarily to avoid the ABS activating and when I pulled the ABS fuse the Cruise control quit working. There are separate fuses for the ABS and for the cruise. Will pulling the ABS fuse dis-able the cruise? Is it supposed to work that way?


  • I have a 2003 2dr. Chevy Blazer and the 4wd just went for the third time (once a year for the past three years). Since I'm leasing it, it is being fixed free of charge, but my lease is running out in March and I have to decide whether or not to keep it (and won't if this is a chronic problem with the 4wd). Has anyone heard of this being a chronic problem (i.e. bad units being produced)?

  • guestguest Posts: 770
    All newer 4wd systems seem to have some quirks due to the move to shift on the fly smart systems. You never said what problems you had but if you read the posts most are small things that the owner can easily fix. Search other forums and see if your "next" vehicle has any problems. If not, then turn it in. The ZR 2dr was pretty good off road but not the best on road and the back seat is terrible so if any family now or planned dump it.
  • Thanks! The problem I have had three times so far is: when I clicked the button to shift into 4WD from 2WD it made a grinding noise and then went dead (i.e. it was in 4WD high and I was unable to shift back into 2WD). Each time they've replaced the the unit and once the dashboard switch (although that has gone once as well). I was just wondering if anyone's heard of these 4WD units being defective. I love the truck otherwise and have not had one problem in 4 years other than this, but since I need the 4WD, if it is I'll dump it for something else.
  • Which part the encoder motor? Is this a 3 button dash switch? Problem depends on case type and exact area and did a GM dealer work on it?
  • It is a 3-button dash switch, and each time a GM dealer has worked on it; they've replaced the unit each time.
  • guestguest Posts: 770
    If they are just changing the dash switch thats why it keeps craping on you - there is a vac line to the transfer case 3 port switch that the encoder motor for 4HI directs vac to the front actuator and engages the front driveshaft. Sensors tell the TCCM (4wd computer) status and allows all to occur. 4Lo then has the encoder motor further engage the low gear. Someone isn't finishing the complete fix.
  • Actually, they've replaced the switch as well as the transfer case (which is always the problem). When it's gone on me it has made a grinding noise and then it gets stuck in 4WD (as it is now). It seems to happen when it's cold; I live in the Northeast and need the 4WD for winter, so this is a huge problem. I'm just wondering if anyone has heard of this being a chronic problem, i.e. that the transfer case units are junk. I'm thinking they are, since this has happened to me 3 times in 4 years, two of them when I really needed the 4WD (in major snow storms). I'm thinking that it's time to let this car go at the end of lease and get something reliable.
  • I had mine into the dealership (full extended warranty :)) last week. Thumped into 4hi on the fly and stuck. Got it back out in neutral only to have it stuck there. They changed the transfer case control module. Switched to 4hi once then tried on the morning I needed it. Tried in neutral moving, neutral still, in gear and both 4hi and 4lo lights would only blink at me. Then in the parking lot in neutral I tried again to go into 4hi and it thumped into 4lo. Ok enough of that.

    Back to the dealership. They called and said my battery wasn't good enough to engage the motor (my volt meter never wavered...seemed to hold a charge ok). I said go ahead and replace it. They called back and said there was another problem with the encoder motor.....they are in the process of replacing that now. Seems to me diagnostics would have shown that right away. I questioned the need for a new battery but not having tested it myself have to succumb.
  • Yep, they were winging it. How much for that Delco battery - ask them to put the original back if that wasn't the problem or just pay it (only battery cost as that was NOT the problem you brought it in for and did not fix it - but you're a good guy so ....) As for a 2003 encoder motor if you are in a wet salt use state thats possible and that was free so ... sounds good if it now works.
  • They just called and said with the new encoder motor, they still can't get it to go into 4hi (just 4lo). I gave them some info from here, wiring harness and vacuum line and they said that's where there going next. They also said the battery failed on the diagnostics........I'm on my way over to get a loaner. Thanks for the forum and the info. Will keep you posted.
  • I looked back and never saw if this was a 3 or 4 button dash switch - 4 is Autotrac case. If it went into 4Lo then the front axle coupler worked. 3 button np233 case the encoder steps once to 4HI and sends vac to front actuator via a 3 port vac switch on the case and engages the front drive shaft. Steps again for 4Lo.

    Autotrac np 236 case is different and front driveshaft always on. For 4Hi you have a firewall solenoid that the TCCM energizes to supply vac to the front actuator and the encoder only steps for 4LO.

    Would look at TCCM,dash switch, 3port or firewall solenoid (by type) or a cut wire/loose connector. First I hope they tried to reset the TCCM by removing power for 30 minutes.
  • I'm sure this topic has been discussed on the boards before, but I could not find anything about it. I have a 2001 Chevy Blazer that I've never had a problem with until recently. In the past snowstorm I put it into 4 wheel drive (3 buttons on dashboard) and everything was fine. But when I tried to put it back into 2, it would only blink a few times but go back into 4hi. After turning the car off and back on it eventually went back into 2wd. Now when I try to put it into 4wd, low or hi, I can't. The buttons don't blink, I don't hear any noises or anything. The only way i get anything out of the buttons is if i put it into neutral, in which 4hi and low will blink 2 times but then remain in 2wd. Any ideas on what the problem could be? Could i fix it myself or do i have to take it to a dealer and how much could it cost to fix?
  • Sounds like the same problem I am having with my 2004 Blazer. It will go into 2 hi and 4 low the lights will blink but WILL NOT go into 4 hi. Chevy dealership stated that I had to put it on the computer to find out what the exact problem is. ANYBODY KNOW WHAT IT IS AND HOW I CAN FIX IT WITHOUT SPENDING A FORTUNE ?
  • Sounds like the same problem I am having with my 2004 Blazer. It will go into 2 hi and 4 low the lights will blink but WILL NOT go into 4 hi. Chevy dealership stated that I had to put it on the computer to find out what the exact problem is. ANYBODY KNOW WHAT IT IS AND HOW I CAN FIX IT WITHOUT SPENDING A FORTUNE ?
  • Check the vac lines under hood and to the reserior drivers side fender. Then 3 port vac switch on transfer case. Then encoder motor must steps once for 4Hi and 2nd time for 4Lo. Then TCCM computer must see all sensors response good. Pull battery power for 30 min and see if TCCM resets. There are many posts on all these found with a search.
  • 93 chevy s10 Blazer 4wd hi lo switch not working checked accumulator fine replaced 3way ball switch on TC. I can get my 4wd switch to work fine as long as the truck is in neutral it will go into 4wd low-high and back to 2wd. Didnt realize it would work in neutral until after working on truck i realized i was stuck in 4wd high but the light on dash didn't indicate anything got to trying anything to get it out and discovered it worked in neutral. Any advice?
  • N is the only position you can go to 4 Lo in - always was. As for 4Hi the encoder motor probably has rust or crap on it and is hanging up - remove and inspect/replace as necessary. Th edash switch sends a voltage to the TCCM to tell it what to be in and if the lights out thats probably bad or connector to the TCCM dirty. Believe on yours its behind the center console/ashtray area.
  • cnm50cnm50 Posts: 1
    I have an 03 trailblazer. The 4 WD light will switch to 4hi &awd.The light will stay on like it should. You can hear it actuate. It will sometimes make a grinding noise and you can hear it grind into gear. once it is in gear it seems to work fine. It seems the only way to get it in 4WD is to stop, switch it into 4WD then creep forward untill you can hear the gears mesh.
  • I'd look at the vac to the front axle actuator and make sure the line is good - sounds like a partial vac so the front axle coupler is slowly engaging.
  • kenagirlkenagirl Posts: 4
    I recently replaced the baring/hub assembly on the driver's front side of my 98 Chevy Blazer. I also replaced the front tires, as they were bigger than the back tires. Truck drove great and 4WD worked like a charm through the last couple of snow storms. However, just a couple of days later, the alignment is off, the steering wheel sits crooked to make the vehicle drive straight and the steering feels very loose. Do you think this is due to 4WD use? What should I check for? Highway driving has become a bit scary. I would appreciate any advise you may have to offer. My regular mechanic has retired and closed shop and I'm at a bit of a loss now. Much appreciated as always.
    Kenagirl. :confuse:
  • repairdogrepairdog Posts: 948
    Have an alignment shop check the front end out. My guess is worn steering components such as the lower ball joints, tie rods, or idle arm and the shop can pinpoint for you - estimates are always free. This assumes the hub replaced was correctly bolted in and all items tightened and that the other hub is OK.
  • scoop2scoop2 Posts: 2
    I have a grinding noise in two wheel drive and when i put in 4 hi it stops i had at a shop and when they took it out for a test drive it was good after i took it home it never made a sound.I used it for a week driving around no noise,i used 4 hi and went back to 2 hi was ok and then all of a sudden it started to made a grinding noise but it seem to be coming from the right hand side,it seem to shift from 2 hito 4hi with no problem the only thing when making sharp turn 2 hi is seem to be jerky
  • repairdogrepairdog Posts: 948
    Would have to point to the front axle coupler partially engaging due to a leaking vac solenoid located on the firewall. Follow that vac line from the drivers side and you will see the solenoid. Pull that line, plug it with a golf T or something and see if that fixes the noise. If so simply unclip that solenoid and get a new one at the dealer - you need the part or # to help them about $30.
    If thats not it check the front diff fluid and transfer case fluid.
  • scoop2scoop2 Posts: 2
    i have 2001 blazer that realy hard on fuel it gets about 13to15 miles to the gallon i phoned gm and they said they can't do anything and they are a little hard on fuel so is there any reason i can't put a fuel mizer cam in it and if so what do i have to do to the computer thanks
  • repairdogrepairdog Posts: 948
    Wrong approach. Depending on gearing (3.42 vs 3.73) and how you drive you have a problem that is simple maintenence. My 99 4wd gets 20mpg avg with the lower 3.73 gears if I drive normally, but if cranked up to 80 over 2500rpm constant down to 18, add AC on down to 16. Slow her down to 70 and mpg go up. Other 4wds with the 3.42 I have get same but alittle better at highway as rpms lower. If you have 2wd then should be better by 1-2 mpg also.

    So, tune it up - cap/rotor/plugs/wires/air filter and clean the MAF sensor in the intake (if you use a K&N oiled filter that is common problem as owners over oil and get sucked onto sensor and milegae drops). Any brakes dragging (like the rears if a recent brake job that did not replace the rear calipers). Something easy is wrong.
  • repairdogrepairdog Posts: 948
    ABS sensors are contained in the new hubs so whoever installed them probably ripped one of the senor wires or didn't plug the connector in all the way - get them to fix it. Without looking at the wiring diagram I'd say the ABS (brakes) has to be working due to the cruise is kicked off by the brake being applied so computer assumes brake on or problems so deactivates the cruise.
  • most automatic vehicles tend to move(in DRIVE) immediately once you release the brake.
    However, my 2001 blazer just stands still even when the engine is cold (and idles faster). On pushing the accelerator slowly, the engine revs up to 1500 - 1600 rpm and only then +- half a second later you feel the torque convertrer doing its job and the car starts moving.
    does this indicate a problem or is it normal for blazers?
  • repairdogrepairdog Posts: 948
    This is a problem. Should go immediately, unless the rear calipers are locking up or if pulling a heavy trailer. Check the trans fluid level and fill if required - engine idling and note the hot and cold lines on the stick. If full get the filter changed next.
  • acarlsonacarlson Posts: 1
    Ok, I'm sure that people have posted this before, I've seen some of them. My 99' Blazer is stuck in 4Lo, I made sure it was nuetral, I checked all the vacuum hoses and I disconnected the battery in hopes that it would reset the computer but thus far it's still stuck in 4Lo. I am trying to see what else I can to try and fix it before I decide to take it to a mechanic. So if theres anyone who has any suggestions please let me know.
  • repairdogrepairdog Posts: 948
    Put the vac source line to the front axle (drivers side under hood) and see if it drops out when you push 2wd. As the many posts have talked about you have vac, transfer case encoder motor, that TCCM or computer in the pass isde kick panel (put the conncetor and make sure its clean and tight), and the front actuator.
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