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Chevy S10 - GMC S15 and Sonoma Transmission Problems



  • :shades: :shades: I just a 96 S10 2.2 liter 4l60E Overdrive Automatic. It had 82,000 miles in good condition. the shift seleonoids are bad only had 2nd and 3rd gear. I took the truck to the transmission shop, I had the transmission flushed, new fluid filter and seleonoids, the problem was fixed. Axp 1,000 miles later while I was driving in town it instantly downshifted into 1st like someone was putting the brakes, but only for 5-10 seconds. Then it seemed fine. The next morning I was driving to work, about 5 miles, and about the time I got to work it did it again. I seem to have all my gears, but it is doing it all the time now. I can not get up to speed, up to 20 mph. I was told that the automatic transmission behind the 4 cyclinders are prone to failure is there any truth to that, if it is bad and have to have it replaced, I don't want to have to worry about it failing early again.
  • gonogogonogo Posts: 879
    Take it to a good independent transmission shop and have them scan it with a transmission capable scanner. That will give you a better idea of what is going on.
    From what I have read the 4 fails about the same as the 6cyl.
    My 4 auto has only 53K, so I don't know how long mine will last.
  • I dont know! But my dad just gave me a 1998 S10 LS three weeks ago and the reverse gear slipped three or four times and went out yesterday, but still works fine otherwise. Any ideas let me know please? My friend said it could be the linkage and I could fix it, I have no idea about this.
  • Ok, my problem with my transmission is this.. i have a 2000 gmc sonoma, 2.2. 2x4.. automatic... i will be cruising down the road in top gear(4th) .. and it will downshift into 3rd gear.. it will not shift back up. even if you floor it.. the only way i can get it to go back into 4th.. is to pull over and turn the ing, completely off, and turn it back on.. that will fix it momentarily. only for it to happen again about 15 mins later.. ive noticed it only happens on long trips. its ver irritatiing. after about an hour of freeway driving.. you cant just pull over and pull back out, u have to acutally turn the car off for it to be fixed.. also.. the service engine soon light is on, and its gives a code for the transmission.. does anyone have a clue as to whats causing this.. anyhelp will be greatly appreciated..
  • gonogogonogo Posts: 879
    I bet it will be PO 1870 slipping. The latest information I got on this malfunction are worn pump bushings. Earlier the fix was repaired or remanufactured valve body.
    The thing is to replace the worn pump bushings the transmission has to come out, the valve body can be done in place.
    You need to go to a good independent transmission shop, stay away from the chain shops, they just want to replace the complete unit.
  • yea thats the code it was throwing.. so i dont need to pay for a complete rebuild? or about what would that run me $
  • gonogogonogo Posts: 879
    Can’t help on pricing, you could ask for an estimate from a good independent transmission shop. A repair can be done, but if high mileage they will recommend a rebuild.
  • hoodlatchhoodlatch Mid-westPosts: 255
    Help! I’m at my wits end. Did you ever see a tranny that throws all its codes at one time? It’s an automatic on a 97 S10, 4.3 with 90k on it. In our case it is intermittent. Sometimes it will allow you to clear all the codes and it runs beautiful. Then out of the blue is goes snafu and has all the codes you can mention on a tranny. I'm confident it’s an electrical thing. I pulled the pan, replaced the two solenoids to the tcc, and replaced the filter, fluid. All of which looked A OK. The bottom of the pan was clean; the fluid was bright red from where I changed it last year. When I put it back together and backed it out of the shop the light came on and still had all the codes it had before. Basically I wasted half a day not to mention the parts cost. What ever happened to good ole power-glides? If you have any suggestions on what magic does the trick please let us know? John :cry:
  • gonogogonogo Posts: 879
    Remove the large 20 pin plug into the transmission and see if it has transmission fluid in it. This has been an issue at times.
  • hoodlatchhoodlatch Mid-westPosts: 255
    Thanks for the reply. Actually the 20 pin plug you mentioned got changed out with the wiring harness that goes to one of the solenoids that I changed last week end. We pulled and inspected all the plugs to the PCM, fuses, associated wiring, all checked out. I think there's an open circuit somewhere. But it doesn't do it all the time. That's the frustrating part. :confuse:
  • Hi, where you able to get any advice on your problem? my 98 sonoma 4.3 v6 is surging also, I have had it to a few shops any no answers yet. frustrating!
  • I Have a 94 S10 with 70,000, pulled some heavy loads withit and tranny went out no gears after fluid change. replaced with Astro Van xmsn with 17,000 miles on. worked great for 500 miles and now it is out same problems. xcept this time put in reverse it slides in gear until rpms increase then it chatters bad and feels like it will shake apart. all forward gears are fine until up to temp then nothing. Replaced fluid and filter again, same gripe. Could it be something external to xmsn or do I need to replace/rebuild. I was a Helicopter Mechanic for 8 years in the Marine Corps, and auto xmsns are as complex, thank God for you tranny guys, or should I specify Transmission Experts. Tranny has a bad connotation, hense aircraft abbreviation XMSN or QMSN. Another perfectly good mechanical word gone bad.
  • gonogogonogo Posts: 879
    The ignition switch has been a known problem, the one at the lower column. Usually at the same time the cluster acts weird.
  • arienarien Posts: 4
    No, No reply yet. It is also the second time I have tried to get any help on this site. What I have been told by a couple independent mechanics is that the overdrive part of the transmission is going out. Which would mean a rebuild or new trans, neither of which I can afford. I still owe 2 years on the truck too, so it sounds like I am screwed. Does your truck have any codes showing? Mine still has not, and I have had it hooked up to a diagnostic machine and driven, and STILL nothing showed. Is your gas mileage dropping? I have gone from 400 miles a tank to 250 a tank. If anyone else is reading this, can you PLEASE reply as to whether it is the trans or not? The problem is getting worse and occuring in higher gears now, as well as hesitating when I hit the gas to turn and cross traffic. Good luck with your problem, maybe we'll both get an answer soon.
  • i do not have any codes that show up. but it seems my gas milage has not changed, I put abot 400 miles a week on, always in the 19-20mpg -98 v6 auto 2wd I live in north wi. I put fuel pump,filter $600, throttle position sensor $50 varrilble speed sensor$50 erg $250.00 chnged tranny fulid & filter$55 so you see why Im frustrated. I now thing a traany rebuild price quote $850 I have 183,000 miles on it. At thispoint it just surging 4 500 rpms not slipping yet. :mad: :sick:
  • hoodlatchhoodlatch Mid-westPosts: 255
    I went to a junk yard last week end and pulled a switch just to see what they look like. The one I seen had three contacts in it. Maybe the one in Dad's S10 has some dirt in a contact thats causing intermittent power loss to the transmission?

    I went to the library last night to research wiring diagrams. From the diagram I looked at I couldn't tell much. The wire for the solenoids coming up from the transmission ended at a fuse. The diagram ended there.

    I can see this is going to be time consuming but I'm convinced there is nothing wrong with the transmission its self.

    I'll keep ya posted. :blush:
  • alrataalrata Posts: 3
    My 99 4 wheel drive S-10 trans whines when I take off and the noise decresses as the speed increases, then it shifts and again the noise is loud at first and again decreasses as the speed increases till it shifts into overdrive. In overdrive it doesn't make any noise, trans is a 4L60E automatic. Anybody have any idea whats wrong? Is it the converter or maybe front pump on trans, just guessing..need help
  • rhtransrhtrans Posts: 84
    Is the noise there in park or neutral? If not then its not the pump. If the noise starts as soon as you put it in gear without moving its most likely the torque converter. but if the noise is only there when you are moving and changes with shfts and speed then most like an internal thrust bearing or planetary gear noise
  • rhtransrhtrans Posts: 84
    Replace the ignition switch in the column. Very common problem.
  • alrataalrata Posts: 3
    The noise starts when I put it in gear, not park or neutral, and stops as soon as it shifts into overdrive. it does change with speed, it starts off loud and decreases with speed.

    Thanks for the answer
  • If the wrong shifter bolts were removed from shift tower when removing trans, the bias springs fly out causing the shifter not to center,or they put the tower together wrong, there is no parts available from GM so they usually get put back together with parts missing!! Only the four bolts at the base of the tower need to be removed.
  • rhtransrhtrans Posts: 84
    If the noise is there when you're "not moving" while in's in the the torque converter. If it only makes noise in gear while "moving" it's an internal transmission problem...bearings, gears, etc
  • hoodlatchhoodlatch Mid-westPosts: 255
    Replaced the ignition starter switch. Seems to have fixed the problem with the transmission shifting. Thanks for the info. :)
  • Ive got a 2002 S10. Love the truck. BUT i had the transfer case replaced 5k miles ago and now im having trouble with the trans. If i try and maintain speed of about 65-70. The Rpms surge and the tranny tries to kick down to 3rd but never takes. Im thinking its the start of the end for the trans. Am I right in thinking this way or is there something else im overlooking? Im about ready to give up on this damn thing.

  • I'm looking at buying a 1987 GMC s15, 4 cylinder automatic with 105,000 miles on it. While driving it I noticed that it shifts 1st to 2nd ok, but really takes some time/ high rpms to shift into 3rd. The salesman said thats the nature of the 4 cylinder s15 and that new ones do the same thing. Does this sound right?
  • jpfjpf Posts: 496
    That 4 cylinder engine I believe is the 2.5 liter or "Iron Duke." I had two cars with that engine and the 3 speed automatic. The transmissions were reliable but the solenoid switch tended to fail ($250 repair). You can tell that it is this switch because when you decelerate the vehicle will stall as you come to a stop. That's the only problem that I have heard with GM's 3 speed automatics from that era. Good luck.
  • gonogogonogo Posts: 879
    No, the new pickup don't do that. Either walk away or have them fix it before you sign any papers.
  • arienarien Posts: 4
    FYI--I finally found someone locally who figured out what was wrong with my seems to have done the trick! The Brake Sensor also controls the Torque Converter. Mine was going bad, so not only did my brake lights not work well, but the Torque converter was not working correctly. About a $20 part--$60 labor, of course, but better than a rebuild!! Try this, and good luck!
  • jfreejfree Posts: 5
    I just replaced the transmission on my 144k Sonoma yesterday for the second time. After driving it only 50 miles on the highway in cruise control it started having the same symptoms it had before I replaced it. It slows down and then revs and downshifts, trying to stay at speed. I limped it home, now it wont move when I put it in reverse. My ABS light comes on at highway speed, usually over 75mph, and the brake light flashes at this speed on and off with no pattern. The lights have done this for the last 80k miles, a mech told me its just the ABS sensor gone bad. ABS has worked fine the few times I have had to use it. Tranny fluid level is fine. I read in a previous post that the brake sensor is somehow connected to the torque converter, don't see how, unless it tries to use the engine to slow the truck during hard braking. Any insight, similar experiences, and help would be greatly appreciated. I hate to think $900+, crawling around under my truck for fourteen or so hours, and a stinking fluid stained garage floor are all for nothing.
  • gonogogonogo Posts: 879
    Engine problems make the transmission do strange things, I would look at an engine problem, like fuel delivery.
    When you step the brake it disengages the torque converter clutch.
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