Tranny Problem..please Help!!

Hi,
We bought a used 98 Blazer,2 WD, 4.3 about 4 months ago. It was running fine for a couple months and then the SES light would turn on and off after highway rides, which are not often. Last month it turned on again and stayed on. We scanned it, and it shows the P1870 twice. 1 is now historic. We cleared the codes, and yesterday I took it over to AAMCO,told them what it was doing,(the hard 1-2 shift,then it goes away after the truck cools down,what code we pulled,asked about the TCC solenoid, valve body,etc.) They say it's shifting late in all gears, which I don't feel when I drive it, and that the fluid was burnt and they want to remove the trans and open it for $400. because whatever is wrong with it, is an "internal" problem.
This truck is only a run-to-the-grocery-store truck. It is not driven everyday. Once that light came on, we've only driven it very short distances. Could it have really sustained that much damage in the few months that this SES light showed up? Enough for a rebuild? Beause that's what they were leading up to. AAMCO gave me their quote for a rebuild after a 20 minute once over. $1250. I am starting my search for other tranny shops today, but just wanted your opinion on just how bad this trans could have gotten in such a short time. I am also afraid to get the fluid changed, I've heard that's not a good idea when AAMCO says it's burnt and contaminated. The fluid is a reddish brown. I don't see contamination, but I'm not a tranny expert.
Any opinions? Advice? All is welcome..

Not positive about the 98 2WD 4.3L, but the 97 4WD 4.3L employs the 4L60E transmission. The E stands for electronic - shift timing is controlled by the Vehicle Control Module - it supplies GROUND to the appropriate shift solenoid in the transmission. If the transmission shifts through the entire range 1-2, 2-3, 3-OD then the shift solenoids are good.
I would spend the $20-$30 for a new transmission pan gasket and filter, and several quarts of transmission fluid. Drain the transmission fluid and replace the filter myself - care should be taken when reinstalling the filter and/or pan as the internal wiring harness can get crushed causing a permanent short (blown transmission fuse) and a $100+ replacement.

Wow this is exactly what mine is doing. My mechanic did the transmission fluid change etc and the light came back on after running the AC for a while and now it shifts hard. What to do, what to do. :screwy:

Hi,
We bought a used 98 Blazer,2 WD, 4.3 about 4 months ago. It was running fine for a couple months and then the SES light would turn on and off after highway rides, which are not often. Last month it turned on again and stayed on. We scanned it, and it shows the P1870 twice. 1 is now historic. We cleared the codes, and yesterday I took it over to AAMCO,told them what it was doing,(the hard 1-2 shift,then it goes away after the truck cools down,what code we pulled,asked about the TCC solenoid, valve body,etc.) They say it's shifting late in all gears, which I don't feel when I drive it, and that the fluid was burnt and they want to remove the trans and open it for $400. because whatever is wrong with it, is an "internal" problem.
This truck is only a run-to-the-grocery-store truck. It is not driven everyday. Once that light came on, we've only driven it very short distances. Could it have really sustained that much damage in the few months that this SES light showed up? Enough for a rebuild? Beause that's what they were leading up to. AAMCO gave me their quote for a rebuild after a 20 minute once over. $1250. I am starting my search for other tranny shops today, but just wanted your opinion on just how bad this trans could have gotten in such a short time. I am also afraid to get the fluid changed, I've heard that's not a good idea when AAMCO says it's burnt and contaminated. The fluid is a reddish brown. I don't see contamination, but I'm not a tranny expert.
Any opinions? Advice? All is welcome..

yes, i see alot of this when i search on here...just wondering if is ok to change fluid if it is contaminated, or will my truck go into a hissy fit.

My 99 was doing the 1-2 hard shift , got new filter, 5 or 6 qts of trans fluid, bought a tcc-pwm (transmission clutch control pulse width modualtor) solenoid.. it is easily accessible after draining fluid and removing pan..

Hi, my 98 4x4 is doing the exact same and AAMCO wanted 2300 + to rebuild without LOOKING at the fluid or pan. I have it with a good honest guy who will hopefully pinpoint the problem and hopefully its the valve body (which is external) which is what goes bad and causes the problem. My fluid looks good and does not smell. This seems to be a common problem :(

From what I've read, it is fairly common for one or another of the valves in the valve body to wear and begin leaking (more so when the fluid is warm and thin) and cause loss of pressure which leads to harsh shifts (run through) or slippage that wears the clutches prematurely. I think it is the boost valve that is often the culprit, but the TCC solenoids are also known to be under-engineered. However, for my money, I would almost always try the fresh fluid fresh filter fix (less than $30) before spending the big bucks to let a trans shop rebuild the whole thing or even the valve body. Your chances of fixing anything might only be 1 in 5 or less, but given the difference in expense, I would still take that gamble.

From what I've read, it is fairly common for one or another of the valves in the valve body to wear and begin leaking (more so when the fluid is warm and thin) and cause loss of pressure which leads to harsh shifts (run through) or slippage that wears the clutches prematurely. I think it is the boost valve that is often the culprit, but the TCC solenoids are also known to be under-engineered. However, for my money, I would almost always try the fresh fluid fresh filter fix (less than $30) before spending the big bucks to let a trans shop rebuild the whole thing or even the valve body. Your chances of fixing anything might only be 1 in 5 or less, but given the difference in expense, I would still take that gamble.

By the way, Sonnax makes repair kits for the worn valve issues. If you can pin down the problem to this area and you're a do-it-yourselfer, you can probably repair your own valve body for a lot less than the trans shops. If your fluid isn't showing any signs that the clutches are too far gone already, you might buy a lot of miles for the price of the kit.

anyone have pix or directions on inspecting the tcc while the trans pan is down? i mean, if i'm going thru the trouble of changing out the filter and fluid, which IS a little nasty looking, is there a way to check if the tcc is bad or not? i don't even know where to begin to look for it.

Changing the fluid and filter is not going to fix this problem (as diehlga points out). Blazee posted a TSB that says a P1870 and a harsh upshift may mean that you need to replace the valve body on the 4L60-E. There is tons of info available on the internet on replacing the valve body vs other potential fixes. In my opinion, they all cost about the same amount (~$150). I looked at all the options and decided to replace the valve body. I will know soon if that worked for me (have only driven to the grocery store once so far - my Blazer is a grocery store truck too - 97 4.3L Blazer). My trans fluid looked brand new. One option I did not look at real hard was the "do-nothing" option. With a grocery-store-truck, that may actually be a viable option - I do not know. It may be the best option if you have low DIY skills and would have a shop do your tranny work for you (may cost ~ $900 for a shop to do a valve body replacement for example).

i have a 99 blazer, it was doing the hard 1=2 shift, i replaced the tcc-pwm solenoid 27.50 full delivered price. drop pan, drain fluid, solenoid is right there, put in new filter & o ring, new gasket, about 4 qts of new tranny fluid. Solved the problem on our blazer 4l60e

My '97 Blazer is doing the same thing....when I drive on the highway for a while, then drop into town, it slams from 1st-2nd from every dead stop. (only does this in the summer though).

What I found was that when it's doing this, I can pull over, turn the ignition off for about 5 seconds, then start back up & it will drive fine.
This led me to believe that the problem is electrical, rather than with the TCC apply valve which apparently is a common problem.

I've read on this forum & elsewhere that the infamous 97 Blazer ignition switch can make the tranny shift hard under conditions like this, so I finally replaced the switch today. took it on the highway for ~40 miles, & got back into town & it's still acting the same way...hard shift 1-2, I can shut down for 5 seconds, & she does great all the way home.

Wonder if the replacing the TCC-PWM solenoid deal would help? I still think it's gotta be an electronic component since it corrects (temporarily) by shutting down for such a short time; I'm guessing if it were a case of the valve overheating/expanding, 5 seconds wouldn't be enough time for it to shrink back.

Hmmmm...

-Mike

I've had 2 vehicles do this very same thing to me. One was a 97 s10 4x4 with 150,000.. The problem with that truck was it shifted fine for about 15 minutes of driving then it would start to shift real hard.. Pull over let it cool and it would be fine until it heated up again. Second was a 98 S10 blazer with 80,000 miles on it and that truck would slam in second and third gear all the time. I had replaced the valve body on both trucks(Myself) and that fixed both problems. Now even if they rebuilt your transmission without rebuilding your valve body you would end up with the same problem. If this was me I would replace the valve body and put in a new trans filter and fluid. Good Luck

Is anyone getting codes or lightd from this problem?

It almost always sets a code 1870 (component slip) on my '97.

I can pull over, turn the ignition off for a few seconds & start again and the truck will shift fine, though the light stays on for a few days.

sad news...
I finally took the truck in to the trans shop. After going over all the options, I finally gave permission for them to drop the trans. Turns out, yes it is the valve body, but also the clutches were cooked, and 2 check balls were stuck. You could see the indent on the plate. They said it still ran well, considering everything they found. They are rebuilding it, updating w/sonnax, this afternoon. $1200. I guess I knew it was coming. Hopefully this is one less headache for us now. Just about anything else that goes wrong, we can do ourseves. But trannys are a no-no.
And, while it was up on the rack, I noticed a fresh oil leak.......I hope it's not where it appears to be..the oil pan!

This is exactly what happens to the tranny when you have a bad TCC regulator valve that is worn, which is almost always the problem with these valve bodies. This is the common sonnax part everyone talks about. The part is not that expensive, and is rather easy to install if you have the specific reamer that is required. The reamer though is expensive (Around $ 150.00)

You usually will get the common P1870 code, indicating trans component slipping, sending max line pressure to the transmission, giving you the hard 1-2, and basically slowly, yet surely destroying your transmission. Anyone who drives with the P1870 code and does nothing about it, should be prepared to rebuild their transmission, becuase it will eventually fail.

The TCC PWM solonoid can cause a harsh 1-2 shift also, but this can be checked with a scanner while test driving the truck. The scanner will verify if the PWM is within range. If its not within range, the PWM would have to be replaced. If its sending proper voltage values to the scanner, then the next thing to look at(assuming all other readings from the transmission are within spec. and no service engine light is on, is to look at the TCC valve regulator (the sonnax part).

The check balls are common, Trans-Go makes a thicker valve body plate that resists the common problem of check balls going through the valve body plate. The Trans-Go also resists the rusting, which is common on these plates also.

The clutches they are referring to usually are the 3-4 clutches. They are a very common problem, and burn up as a result of the TCC regulator wearing out in the valve body. A very advisable thing to do(especially if you plan on keeping it or if you do a lot of towing), is to upgrade the weak 3-4 clutches to something like the Raybestos Z-Pack, or Alto 9-clutch pack. They can take the higher stress in these trannies, and last a lot longer than OEM. That being said, the O.E. 3-4 clutch pack has been redesigned to take more stress than the previous ones used. In my opinion, I still don't think they are good enough.

Another good thing to do is to just replace the sun gear shell with a stronger, better built unit. Something like "the beast", or something stronger. This is a very weak point in the 4L60e.


Ask and see what they replace, and what they leave in the tranny. Some builders will replace bushings, bearings, all clutches and stuff, others will just replace whats broken. This last option is not a full rebuild, just a fix(hopefully). Either way, I hope this helps give you an idea as to whats going on.

Also, here is a link for the Sonnax TCC regulator.
http://www.transmissionspecialty.com/parts/PDF/77754-Combo(rb).pdf

blazes9395
thanks for all the info.
I checked into what was being replaced. They brought me into the back room where they rebuild, my parts had just came in. They are replacing everything. I got all the old clutches and stuff from them. Actually, I got the truck back late yesterday afternoon. Drove it for a short time. Seemed o.k. Today I had to take the kids somewhere, got on a mainstreet out of town..Now it seems to be slipping from 1st into 2nd. I took it back to them, just as they were closing. They are going to have the builder come in on Sunday and look at it. I don't know what's wrong with it now. Even before they rebuilt it, it NEVER slipped like this. I hope it's nothing serious, my husband almost blew a blood vessel when he felt it slip like that, especially after shelling out $1200 bux! Oh well, I guess I'll find out tomorrow...stay tuned.

Hey, my 96 felt like it was slippin alittle at highway speeds (pulsing?) My 95 did th same thing:it was low on fluid. i checked the fluid and did the new filter/gasket option, and now the original problem seems better, but the check engine light is now on, the gear indicator light PRNODD21 doesn';t show up at all, and it seems as though it starts out in 1st or maybe 2nd gear. i can't spin the tires in my gravel driveway, unless i manually kick er down to 1 or 2. Please help me figure out what i screwed up. thanks