Lost 4th Gear; Code 28 and 58; 4L60E

[1500z71]

1993 K1500 5.7

Hey guys, looking for a little direction here, as I haven’t been able to find anything with my combination of issues.

Last summer ‘21 my transmission overheated pulling a buddies big pontoon. Pulled over and let it cool, topped it off, ran fine again for a long time until now.

Went on an hour and a half long trip this weekend and completely lost fourth gear. It has been having issues getting there for a few weeks now but as of yesterday it’s completely gone. Was still able to get home and it walked through 1-3 seamlessly, but there is now a second or so lag between R and 1 sometimes, at least that day there was. My check engine light stays on most of the time for EGR, but I checked it as soon as I made it home and it threw Code 28 and 58. Pressure switch and temperature sensor (both transmission) I believe. Few things I’m wondering about -

Code 58:
My question is could running it with high RPMs (~3K) at highway speeds for so long cause it to throw a 58 by running much hotter without the 4th gear? Does it work like that? Or is it saying that the temp. sensor itself has failed?

Code 28:
Did the overheating last summer cause this sensor to fail? How common are failures like this after overhearing?

And then finally - I’ve never torn into a transmission, but I consider myself mechanically inclined. How hard of a job is it fixing these two issues? I’ve got a guy that can rebuild these trannys in a day, but I always like to at least look into myself first.

Or is this basically tell-tale that the tranny is on the way out after overheating this summer?

 

[1998_K1500_Sub]

I'm pondering what may have happened.

From what I remember (I don't have my 700R4 Technician's Manual handy) the shift from 3rd to 4th is caused by engaging the band, the same band that's involved in 2nd gear as well. Since you claim it shifts 1-2-3, then evidently 2nd gear is functional and the band is able to apply. This suggests to me the problem (well, one problem) is in the valve body. Let's see what others say.

Code 58:
My question is could running it with high RPMs (~3K) at highway speeds for so long cause it to throw a 58 by running much hotter without the 4th gear? Does it work like that? Or is it saying that the temp. sensor itself has failed?

Running in third shouldn't have made much difference typically, but if you were running with the torque converter unlocked (for whatever reason... the trans was already acting-up) it would have run much hotter for at least one and maybe more reasons:

- driving with an unlocked converter is adding heat to the oil, and
- the oil path through the cooler is impaired if operated with the TCC control valve "unlocked"

 

[1997]

how do you know it overheated?
did you tow in O/D, that's something that will kill a 460. How my miles on it? might be rebuild time regardless if its lots ....

running in 3rd at highway speeds wouldn't set a code if things are working as they should.
towing is done in 3rd.

how's the fluid? how long since a fluid and filter? maybe its time.

if you clear the codes do they come back? if so look for the common items in the codes.

i would test shorts/gnds/opens from the ECU connector and use a shop manual.

ECU is a common item but you need to rule out everything else 1st.

 

[1500z71]

I'm pondering what may have happened.

From what I remember (I don't have my 700R4 Technician's Manual handy) the shift from 3rd to 4th is caused by engaging the band, the same band that's involved in 2nd gear as well. Since you claim it shifts 1-2-3, then evidently 2nd gear is functional and the band is able to apply. This suggests to me the problem (well, one problem) is in the valve body. Let's see what others say.



Running in third shouldn't have made much difference typically, but if you were running with the torque converter unlocked (for whatever reason... the trans was already acting-up) it would have run much hotter for at least one and maybe more reasons:

- driving with an unlocked converter is adding heat to the oil, and
- the oil path through the cooler is impaired if operated with the TCC control valve "unlocked"

Oh yeah it’s certainly fine in 1-3. Toward the latter half of that drive I had a good bit of red lights, and I counted the shifts each time and even walked it though on the column a couple times.

How would you be able to tell if the torque converter is unlocked or not? The torque converter was replaced not terribly long ago (I have a post on it) and haven’t had trouble from it since.

 

[stutaeng]

This is a 4L60E, right?

Look here. I've posted this before. Disregard the highlight row:

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I wouldn't think it's the torque converter.

 

[PlayingWithTBI]

Is your 93 trans a 4L60E or a 4L60 (700R4)?

This is a 4L60E, right?

Beat me to it, ha ha! You can test the TCC by cruising at a steady speed in 3rd or 4th above 50 MPH, watch the tach, and lightly tap the brake pedal with your left foot, while maintaining your speed. If your RPMs go up, your TCC is working OK.

 

[1998_K1500_Sub]

How would you be able to tell if the torque converter is unlocked or not? The torque converter was replaced not terribly long ago (I have a post on it) and haven’t had trouble from it since.

If the torque converter's locked then, when you add just a bit more throttle, the engine RPM doesn't just rise immediately before the speed; instead, RPM responds like a manual transmission... engine RPM moves in lockstep with speed.

There are other "seat of the pants" ways of knowing (see others' posts above).

 

[1500z71]

how do you know it overheated?
did you tow in O/D, that's something that will kill a 460. How my miles on it? might be rebuild time regardless if its lots ....

running in 3rd at highway speeds wouldn't set a code if things are working as they should.
towing is done in 3rd.

how's the fluid? how long since a fluid and filter? maybe its time.

if you clear the codes do they come back? if so look for the common items in the codes.

i would test shorts/gnds/opens from the ECU connector and use a shop manual.

ECU is a common item but you need to rule out everything else 1st.

I noticed a little smoke in my rearview, which was quickly followed by a big cloud of smoke when I started to pull over. Smelled burnt transmission fluid for the first time, pretty gnarly smell. But that's the thing - I was towing it in D. I mean it was a good size pontoon, no idea the weight, but it couldn't have been much heavier than hauling a trailer full of cattle like this truck has done plenty of times before, but that's been a long time ago now. Truck has 184K, tough to say on the trans, it's been rebuilt twice before early in it's life, but I would say it has anywhere from 80-100K on it, I can confirm that here in a minute if I can find the papers.

Fluid and filter, possibly when the torque converter was done, if not then I'm not sure. The codes for some reason aren't instant, they only come on after driving more than about 15 minutes. I will try the reset though and let you know.

 

[1998_K1500_Sub]

You must be registered for see images attach

Yes, as I thought, the 2-4 band gets applied... that's the difference between 3rd and 4th. And since 2nd works, and 4 doesn't, that suggests (to me) it's a problem in the valve body.

Of course, the "problem" may be that some hard parts started disintegrating and dumped a lot of debris in the oil, and consequently one or more valves (in the valve body) are gummed-up and aren't working as they should. So... the "problem" isn't really the valve body, it's damaged hard parts.

 

[1998_K1500_Sub]

how do you know it overheated?
did you tow in O/D, that's something that will kill a 460. How my miles on it? might be rebuild time regardless if its lots ....

Yes, towing with the pre-1996 trucks in D is generally a no-no.

My father's 1995 K1500 had a GM sticker on the driver's door that said, basically, "Don't tow in D".

The issue is the pre-1996 ECU doesn't properly interpret the operating conditions which exist under a load when in "D" (such as towing in overdrive) and may not lock up the torque converter; if so, the heat issues I mentioned in my prior post ensue. Not Good.

One can tow in D, but it's up to the driver to monitor the TCC and, if it's running unlocked, take remedial action... which is to shift into 3rd as it facilitates TCC lockup (for reasons I won't try to explain).

(edited later on Feb2)

Note that on certain GMT400s with 4spd auto, overdrive is denoted simply as "D" (on at least 1995 and later, i.e., PRD321) and as "OD" on years prior. In the context of this post, "D" means "overdrive is selected".

I mention "pre-1996 ECU" above. To be more specific, I've personally noticed the described behavior in both 1995 models K1500 and S10 (both using the same ECU and $0D firmware). To my knowledge the 1994 models were similar (ECU and $0D firmware) but possibly with differing configuration parameters for shifts and lockup. Too, reportedly the transmissions are different (see link below).

But, to emphasize the issue, running with the TCC unlocked for any reason on TCC-equipped 700R4 or 4L60(e) transmissions, particularly while towing, has potential consequences for the oil temperature and thus the longevity of the transmission.

The real differences in 700r4/4l60/4l60e transmissions by year

I have been compiling this info for a while, finally got around to posting it. I could not find a thread on here that outlined the actual differences in the automatic transmissions of our trucks. Feel free to comment or ask questions if you need anything. I BELIEVE all this is correct, but feel...

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