Someone help me please!

I have a 2002 Chevy S10 ZR2 4x4, the transmission will shift through 1st and 2nd gear up to 30mph then will not shift anymore. I have notice if you are easy on the gas you make get lucky to shift into 3rd, but the transmission downshifts to 2nd and only 30mph. I’ve tried shifting into 3rd manually, if the rpm is high it will not shift into 3rd but if they’re low it will shift and if you press the accelerator just a little harder it will shift back to second and speed will drop to 30mph. I’ve changed transmission fluid and filter. The fluid was dark. I put DEX VI transmission fluid back in. Problem still exist. If the description doesn’t make any sense please let me know. I just have so much to explain and not sure how. I bought this truck from a person who bought this truck brand new in 2002. He was always kept the truck maintenance but he said he has never changed the transmission fluid. The truck has 276,000 miles but they are mostly highway miles from driving from NC to DC and back. I can assure you guys this truck hasn’t been “dogged”. If you guys have any ideas please let me know. I read one forum and someone said to changed the ignition switch wire harness. I’m not sure if that has anything to do with it, but I only seen one person say that and I’m not sure if it works.

Are any dash lights on? CEL or O/D? At 13 years and 276,000 miles, it may be a case of needing to get the transmission overhauled. Even with good care, which with over 12 years, 250,000 miles and no fluid change this transmission did not get, 276,000 miles is a decent life for a transmission.

A chevy s10 with that many miles has served you well. It’s time for a change. I would not put much money into a fix. Get an estimate. If you do mostly highway driving, I wouldn’t spend much to fix it before I replced it.

@BustedKnuckles There isn’t any CEL lights on. I’m not sure where the overdrive light is.
@dagosa Sorry buddy anything I buy I plan on keeping it. That’s why I buy older cars, parts are cheaper. I have a Honda Accord with the odometer broken at 464,000 miles there is way more miles on that car than that. When the engine stops turning I will buy a $439.99 rebuild kit and rebuild it in the backyard. I’ve successfully done it before. BTW thanks for the advice though!

Just because you don’t have a CEL on, does not mean that there aren’t codes stored in the PCM. The PCM stores codes for the transmission as well.

Most auto parts stores except CA and HI, will read the codes for free. Try that first and if you get a code or two, post the actual code here, not what the counterman tells you what it means. You could have something as simple as a stuck solenoid. But 276k miles is a lot of an automatic transmission. It may need a rebuild.

Since this truck has been pretty well cared for, a rebuild by a local independent may be better than a reman from a national chain.

I dunno, things wear out like transmissions regardless of how well they are maintained. At the least I think a trip to a trans shop for a diagnosis is in order but I suspect your clutches are worn and need an overhaul.

It appears that you are flogging a lame horse. Most likely the 3-4 clutch is slipping badly. The 2-4 band seems to be holding as you have a useable 2nd gear. Since this truck has mostly highway miles, the 3-4 clutch would have been engaged most of the time. Shifting between 3rd and 4th would have been applying and releasing the 2-4 band. With the full engine torque on the 3-4 clutch it eventually will wear out. The black fluid indicates that something was slipping and burning the fluid. Do get the PCM scanned for codes. If possible, pull the freeze frame data from the PCM during the transition from 2nd to 3rd. That will show if 3rd gear is being commanded and any errors in the actual ratio.

If you are mechanically inclined you might try a rebuild on this as there does not appear to be any hard part problems. Get a Chilton or Haynes transmission manual for this transmission; buy the soft part overhaul kit; and go to town. Another route is to get a rebuilt unit from a respected transmission rebuilding firm. Finally you might hunt up a lower mileage recycled transmission from the truck salvage yard.

I wish ‘transman618’ was still active on this site as his knowledge and experience is invaluable.

Good luck on this. Keep us abreast of your progress.

You need to have a proper scan done to see if any transmission codes pop up.

The transmission is 14 years old and never had the fluid/filter changed. It’s time for it to die; the only surprise is that it’s made it this far.
The dark fluid is a sign of overheated fluid and friction material from the clutches.

Many of the seals inside the transmission are designed to hold fluid pressure. Aged rubber loses its elasticity and pressure problems can develop. That in turn can lead to slippage and friction material loss which then leads to darkened transmission fluid.

This kind of failure can occur no matter the type of driving or how gently it was driven. The best cure to prevent transmission failures is regular 30k miles fluid changes and if possible; the installation of an external fluid cooler if the vehicle does not have one.

A lifetime long friend of mine has worked in and run a transmission shop (family business) for about 40 years. He sees trans problems 5-6 days a week all day long and has told me that the vast majority of transmission failures that he sees are caused by one thing; lack of fluid changes.

@ok4450, @researcher, @Bing, @keith Thanks, for all you response. It really helps on my next decision. I am going to get the PCM checked for trouble codes and let you guys know. However, I found (what I seem to think) an awesome on a transmission and I bought it.

I found this transmission at a salvage yard. This transmission has 85,000 and a 6-month warranty. I heard from other people that rebuild transmissions doesn’t seem to last long. I’m not sure if there is a specific break-in procedure that needs to be followed. I seen a forum this morning, someone said that their “rebuilt” transmission only last the length of the warranty.

@dagosa In my neck of the woods, 4x4 S10 pickup trucks seem to hold their value

I’m assuming it’s because the mudders like them, or maybe because they were relatively rare, compared to the rwd S10 pickup trucks

I think the 4x4 S10 trucks actually had a wider and higher stance, and were better equipped

Definitely not your run of the mill S10 gardener’s truck

Not all rebuilt transmissions should be considered to have a short life. There are several ways of rebuilding a transmission; a soft rebuild with seals, gaskets, clutches, etc and a hard rebuild which includes all of the previously mentioned plus all hard parts including bushings, bearings, solenoid pack, update parts, etc, etc.

Many people opt for the cheaper soft version and while most may hold up well a percentage of them may have problems. This is where the complaints and painting all rebuilds with the same brush comes from.

Before installation of a salvage yard unit I would recommend a filter change, and changing any external seals on the transmission such as output shaft and front pump (torque converter) seals along with the engine rear main seal.

The reasoning for that is those seals are aged. Murphy’s First Law states that if you don’t change them then sure as hxxx within 2 weeks one of them will start leaking and the trans will have to come back out just because of a 5-10 dollar seal.

It depends on who rebuilds the transmission. I’ll take a good quality rebuild over a used one any day.

Make sure the engine isn’t worn out first. I would do a compression test and put a vacuum gauge on it. If an engine doesn’t have any power when you put a load on it, the transmission will keep downshifting like you are pulling a steep hill.

rebuild transmissions doesn't seem to last long.

I had my Ford truck auto transmission rebuilt about 100K miles ago and it is still working fine.

A good transmission shop is able to rebuild many types using super-duper parts where you end up w/a transmission that is better and more robust than when it was new. It’s just a matter of what you want and what your budget is.

276K ? There is actually no point in even asking what is wrong. Can you possibly imagine how many times this trans had to go thru its shift cycle? Its in the millions… Its WORN OUT…DEAD…DONE…It owes you and us Nothing. Sorry bout that. How much more do you think you can get out of this tranny? They usually die at 120-140K. You are WAY WAY WAY past due. Your options are limited…Since a low mileage factory tranny is prob not going to be found… Rebuilds are almost comical in their longevity… I’d convert it to manual if i liked the truck enuf. I don’t see a pretty way out of this. Auto transmissions put more vehicles in the salvage yards than any other issue.


I’ve swapped transmissions with one that has 85,000 on it, and the same issue still exist. Any ideas or sugguestions? I’ve replaced the Vehicle Speed Sensor. I’m not sure what it could be. I have no “SES - Service Engine Soon” lights. I’m not sure what to try.

After all that work, installing a replacement transmission and having exactly the same performance issues, it’s pretty clear to me that there is something not right in the management of the transmission. You need either a factory service manual to study or the help of an experienced transmission specialist. Some component outside the transmission itself that directs the operation of the valves and switches inside the transmission is faulty. My knowledge of the electronics of all that is zero, but someone certainly knows, and either that’s going to be you, after a lot of study, or you have to find that elusive expert.

If I’ve swapped transmissions and that’s not the issue than would it be something to check with the transfer case? Any fuses to check?

The other sensor the PCM monitors to determine the transmission shift points is the Throttle Position Sensor. If this was faulty it should affect the timing and severity of the 1-2 shift. If you have a VOM or some means of measuring the resistance of the TPS potentiometer, you might determine if the element is open or the wiper is making intermittant contact. Alternately, replacing the TPS might be cost effective.

At this point a transmission specialist with a scanner capable of capturing the PCM data is needed. A freeze frame grab of the PCM data at the time the transmission should be shifting might show what the PCM is having problems with. Does the throttle show high percentage? Is the PCM commanding 2-3 shift? What are the input and output (VSS) readings?

I went to the stealership and found out that there isn’t anything wrong with the transmission. The problem is the catalytic converter. I removed the catalytic converter and was able to get up to 50 mph in the city. I don’t have any tags on the vehicle so I couldn’t put it on the interstate.