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Chevrolet Blazer GMC Jimmy Transmission Problems



  • Not yet. I suspect it's the BTSI Switch on the shifter, but haven't had a chance yet. I probably won't have a chance to tinker on it for another couple weeks, but I'll repost my progress. Holler back if you get yours figured out in the meantime. Good luck and happy holidays.
  • ok so i just joined to see if someone can help.

    i have a 99 jimmy 4x4 with a 4L60E transmission that is acting up in park no problem.
    when i put in reverse it engages but it jerks the rpms just bounce i go to neutral it stops. i put it in drive a it starts back up and if i put in D1 or "LOW" it dose it worse and kills the motor. please if you can help email me at thanks chris

  • tidestertidester Posts: 10,059
    email me at

    Let's keep the discussion here so everyone will benefit. :)

    tidester, host
    SUVs and Smart Shopper
  • Okay, I've swapped out the shifter, BTSI Solenoid, and the Brake Pedal Switch. None of that fixed my problem and the shifter button would still not depress. I crawled under the truck and fondled the plug that goes into the Neutral Safety Switch and was momentarily able to depress the button. Another attempt wouldn't depress. It was off and on. Everytime I jiggled and tried to repush in the Neutral Safety Switch Plug, I would momentarily get it to work.

    However, even while the button would depress and I could shift the shifter out of park; my truck would still not go forward or reverse at any rpm.

    I've not yet ruled out this being an electrical issue, since I still believe the PCM needs a valid signal from the Neutral Safety Switch to provide an output to the TCC solenoid, which is keeping a tranny fluid exhaust valve open, preventing and fluid from building up which would allow my tranny to engage in any gear other than park. I'm not certain, but that's what I'm pursuing now.

    I've got a great parts truck. A 1997 GMC Jimmy with only 82k original miles. It was wrecked on the driver side (between the doors, damaged the pillar) in 2004-2005. It was parked in a garage and never put on Non-op. So, with 5 years of back registration fees and penalties, the DMV officially killed that truck, which is why I'm parting it out.

    A few days ago, I removed the harness from this parts truck and sometime next week I intend to install it in my 97 blazer; if it still won't engage in forward or reverse, I'll have to swap the tranny out.

    In the meantime, I got a great parts truck if anyone needs anything. It's black, leather, billet grill, etc. ran great until I pulled the harness a few days ago. It'll be on Craigslist in the SF Bay Area in the meantime. I can also list parts on eBay and/or accept pay pal if you need something mailed out.

    Best of luck everyone.
  • jlflemmonsjlflemmons Posts: 2,242
    Well, it sounds like the TTC is locked. Acts sort of like a clutch in a manual tranny. That, or the torque converter itself has failed and is in a locked condition.
  • :mad: i got this blazer about 4 months ago and it had no reverse and hesitated between 2nd and 3rd gear i just got a good transmission out of a 98 blazer($1100 from a neighbor's brother that rolled hiswas working fine for him) and put it in the only thing i had to reuse it the nuteral safety switch and i replaced it with a new one and i still have the same problem... any help will be apprshate
  • Hi,
    when i push the 4x4 button on my 98 4.3l 4x4 blazer, i hear a clicking noise under the dash on the passenger side. the button lights up (no light on the instrument cluster (is there one?)) but front wheels will not turn (tested it on the recent snow) clicks sound like bad axle bearings. Any thoughts?
    Thank you.
  • When the 4WD button is pushed it activates a vacuum actuator located in front of the Battery box that engages the front differential, I suspect it has partially failed and is trying to engage the front end and causing the noise you refered to. Changing it out should cure your problem and give you four wheel drive again.
  • I appreciate this forum for being here!

    I have a 1997 Chevy Blazer, recently purchased with 175,000 miles. Very nice, clean, practically perfect for its age and mileage. Here's what's developed as of late and hope that someone can tell me what might be the problem.

    This truck runs perfectly, until I am on the intestate, and hit a decent incline, going 70, and sometimes midway, the truck will kick into that higher gear (overdrive maybe?) and of course the RPM's go up slightly.. This issue has just started. The "Check Engine Soon" light comes on, blinks, and it's not like the RPM's jumped a great deal either. It sometimes will kick back down to normal once I've cleared the hill, "Check Engine Soon" light stays on, is still on.

    Also, alot of the times, the RPM's will not kick back down at all, as if it is stuck in that higher gear. Eventually the transmission will have a short jerk from 1st to 2nd, taking off from a stop light.

    This seems to happen only when I'm going at a higher rate of speed on the interstate, rather than a 2 lane highway going 55 to 60 mph.

    It seems to 'reset' overnight, and as long as I don't go that one interstate route, everything's cool, no problems in town whatsoever.

    Anyone know what could be the problems?


  • Your transmission is kicking down probably out of lock up in the converter, that's why the rpm's go up, it should return to lockup after the hill has been crested. I don't know why your check engine light is coming on, you should get a scanner to check the codes if you want to know why the light came on. It comes on when a code is set in the ECM.
  • jlflemmonsjlflemmons Posts: 2,242
    Several franchise auto parts stores will read the codes for you. With the miles you indicate, this could be a number of problems, some rather simple. Bad plug wires, rotor, distributor cap, plugs, any of which could cause weak spark and allow the engine to misfire, setting the code.

    The driving condition you describe puts a load on the engine while it is running at low rpm, and if spark is a bit weak, the tranny will sense the additional load on the engine and downshift, or unlock the converter.

    Your first course of action would be to find out what the code is. When you have that, let the forum know and we will help you further.

  • duntovduntov Posts: 133
    The first thing I would replace is the EGR valve. I have the same problem with my '91 S10 Blazer 4x4. Carbon build up in the EGR valve is a common problem with high milage engines. It does not seem to hurt the performance of the engine in ay way. If my SES light comes on after a few miles at 70 MPH, I pull over at the first opportunity and turn off the engine for 10 seconds and the SES light is gone. Otherwise, I just ignore the SES light until I reach my destination.

    I may replace the EGR valve someday if I get tired of seeing the SES light. . I can also install a gasket under the EGR valve assembly that has a fine mesh screen to keep the carbon particles from restricting the movement of the pentel in the EGR valve. You can make a screen out of a fine mesh coffee filter and epoxy it to the gasket. . TOMCO, Inc. offers screened EGR gaskets to help prevent the EGR carbon fouling problem.
  • Thanks Y'all, I will definately look into those possible issues, and get back with the forum! Let's hope it's something simple, and can help other Blazer owners too!

    Talk back at ya soon!

  • Hi, thanks for an answer.
    I got to the vacuum actuator and found that vacuum line is disconnected. Now i have a problem finding where is it coming from to the vacuum actuator.
    Thanks again.
  • Did you hook it up to see if it works?
  • I've read just about most of the post this evening, and have tried some of the answers. I bought a 97 blazer from my sister. My brother in law changed the fluid and filter prior to this problem, or so I'm told. I dropped the pan and replaced the filter and fluid on the chance he put the wrong fluid in it, and have did the Battery Disconnect trick, then took it for a spin for the first time. Fluid is at correct level, no drips or runs. I start out with it feeling like it's driving through syrup, like I'm giving it more gas than needed to go. It will shift from first to second, but when it feels like it's shifting from second to third, it's like I shifted into neutral. (side note; while the pan was off, I did some looking around. I pulled the clip from the 1st/4th solenoid, and a white looking plunger pushed the solenoid out of the hole it was in. I reinserted it and replaced the clip. Upon removing the clip from the 2nd/3rd solenoid, there was no plnger and I had to pull it out of the hole it was in manually. I reinserted it back in and replace that clip. I visually looked at, and physically felt each wire to make sure none of them were nicked or cut. I plan on calling a Mason Brother who is a Service Manager at a Chevy Dealer tomorrow or Monday, so IF I get any answers from him, I'll post them too...
  • Can some one tell me an easy way to tell if a 97 blazer transmission will fit my son's 1998, both trucks are 4x4. Thanks in advance.
  • Check for vacuum leaks! Just had the same problem in my 2000 blazer. Other than that it is probably the vacuum actuator.
  • I have a 97 S-10 Blazer. Sometimes it will not start like it is not in Park. After many tries of wiggling the gear shift and such, then it will start and run fine. Anyone have any ideas about how to fix this.
  • heavnlycareheavnlycare Posts: 1
    edited March 2010
    My Blazer shifts all the time. It shift wrong it will shift up instead of down and visa versa. Also the blinker sound (not the light) blinks when Im not pushing the break. Would all that me connected to the main computer or wires or all seperate problems. PLEASE HELP i'm sick and tired of haveing issues with this truck
  • I have a 1997 Blazer and for the most part it runs strong. I have 132,000 miles on it. I had a problem with the transmission shifting very hard out of 1st gear after I would drive for about a half hour, or when ever the check engine light would come on. This problem occurred with in weeks after buying the vehicle. I drove it this way for about a year and a half. I changed the transmission and with in 10 minutes of putting the new transmission in, I was already experiencing the same problem. My mechanic says its a bad transmission. Could this be an electrical problem? My ignition switch has a tendency to stick and sometimes and probably should be replaced, I cant get the key out of the ignition for weeks. Could this have anything to do with the transmission problem??
  • I'm having the same problem a few of you have discussed here. I have a 96 Blazer 4wd and when I got it at auction and drove it home it shifted OK albeit a little hard from 1st to 2nd. When the vehicle reached operating temperature though, the check engine light came on and it wouldn't downshift to first or shift into overdrive. It would start out in 3rd unless I manually downshifted, and even then it would only downshift to 2nd. I un-hooked the battery for 15 min or so, hooked it back up and the problem went away a few minutes only to trip the check engine light again, and shift goofy again. I have seen replies of "change the fluid and filter" a lot and have yet to do it. I guess what I'm asking is if anyone that has had this exact problem (I've read several instances of it here) changed the fluid and it fix the problem? I know its one of those things to narrow it down, but I want to know if changing the fluid with this particular problem has ever fixed it instead of only ruling it out as a possible cause. So.. that said, what should I do, I am mechanically inclined, I was a certified mechanic at one time (not in transmissions though) and have a few tools. Any help you can provide would be greatly appreciated!! Thanks!
  • gkitegkite Posts: 11
    I have a 96 GMC jimmy, which had the same problem. A friend of mine which worked at a chevrolet dealer did some research and and said that we needed tio replace the wire harness going to transmision. We did and I have not had a problem with it going on 5 years now. the wire harness develops some kind of voltage drop and keeps it from down shifting
  • Was your problem exactly like mine? I want to be sure before I take drastic steps in what could be the wrong direction. I only ask because others have stated they have the EXACT same problem I do.. I just want to be certain.
  • gkitegkite Posts: 11
    I'm pretty sure it is. My check engine light came on and when ever i came to a stop and restated it would start out in like second or third gear, would not down shift to first. also there was no passing gear. At that time i took it in and had the transmission rebuilt. on the way home from picking it up it did the same thing .check engine light back on and no first gear. $1200.00 dollars down the drain. All I can say is when we replaced the wire harnes and pigtail going to transmision my problem went away and has not been back since.
  • tonyb6tonyb6 Posts: 1
    I have a 1995 jimmy , I can put it in drive or overdrive and try to pull out but it is a real strain on it , but if I Put it down in 1st or 2nd and pull out it does fine , then I can put it in drive, then it wont shift in overdrive , I changed the shift silniod but it didnt work , someone help ! Thanks !
  • memebearmemebear Posts: 1
    edited April 2010
    My Blazer won't shift out of 2nd and acts like it's in neutral when it hits 25mph. Has reverse and the fluid, filter and pan was all just changed and clean. Was running fine till a few days ago. Can someone please help me. I love my truck and don't want to get rid of it. :(
  • cmed06cmed06 Posts: 1
    Bought my jimmy 6 years ago from orignial buyer. Good shape, well cared for. Few issues - alternator, a/c. For last year it's had several engine codes dealing with transmission. Taken it to 2 different tranny shops and neither could figure out problem. All codes hint at electrical problems. Could this be a computer issue? Any help would be appreciated.
  • boygoneboygone Posts: 1
    When i start my jimmy after it has been sitting for a couple hours it delays when i put it in drive or reverse, can anyone help, what could this be?

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