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Discussion Starter · #1 ·
With no previous transmission problems, I was on a recent trip and I noticed the rpm on my tach was running about 2500 rpm at 60mph in overdrive (normally runs in the 1700-1800 rpm range at this speed). I manually downshifted to 3rd gear then back to overdrive but rpm remained at 2500. I continued at this pace for about 6 miles to a local Wal-Mart so I could check the transmission fluid and in case I needed to purchase some Dexron. Coming to a stop at my exit, I noticed the transmission did not drop down to 1st gear. When I accelerated, it was still in 2nd gear and slow to move. The passing (kickdown) gear was not operational either. At Wal-Mart, the fluid level was fine and had a nice pink color with no burned smell so I made no additions. Upon leaving Wal-Mart, I shifted manually to 1st gear to see if was working and it was. I then manually shifted up to OD (at highway speed) but the transmission would only go to 3rd gear. On the drive home, I left it in OD to see if there were any changes. No changes at all. So I have a 4L60E in a 1995 Chevrolet K2500 P/U(6-lug) with 95,000 on the clock. Overdrive is not working at all, 3rd and 2nd gears are fine, 1st gear works fine only if shifted manually from a stop. Please HELP! :confused:
 

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trans problems

No check engine light, hum. You should still have it scanned though.

You may want to run it by a trans shop, to let them have a look see.

And by the way, are you sure this is a 4L60E? It may be a 4L80E, different trans, different possibilites, for this concern.
 

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remington7 said:
With no previous transmission problems, I was on a recent trip and I noticed the rpm on my tach was running about 2500 rpm at 60mph in overdrive (normally runs in the 1700-1800 rpm range at this speed). I manually downshifted to 3rd gear then back to overdrive but rpm remained at 2500. I continued at this pace for about 6 miles to a local Wal-Mart so I could check the transmission fluid and in case I needed to purchase some Dexron. Coming to a stop at my exit, I noticed the transmission did not drop down to 1st gear. When I accelerated, it was still in 2nd gear and slow to move. The passing (kickdown) gear was not operational either. At Wal-Mart, the fluid level was fine and had a nice pink color with no burned smell so I made no additions. Upon leaving Wal-Mart, I shifted manually to 1st gear to see if was working and it was. I then manually shifted up to OD (at highway speed) but the transmission would only go to 3rd gear. On the drive home, I left it in OD to see if there were any changes. No changes at all. So I have a 4L60E in a 1995 Chevrolet K2500 P/U(6-lug) with 95,000 on the clock. Overdrive is not working at all, 3rd and 2nd gears are fine, 1st gear works fine only if shifted manually from a stop. Please HELP! :confused:
Check the fuse block for a loose blue wire.

Bogie
 

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Since you have a light duty 2500 series truck if may be a 4L60E....... as Brisco mentions it may be a 4L80E too. Knowing for sure would help the diagnose process.


IF you can get the truck scanned properly to see IF the computer is commanding the correct items and the tranny is responding helps a great deal..

Some break out boxes fit in between the vehicle connector and the trans case connector. You can watch the PCM data stream to the tranny , interrupt it , or operate the trans separate from the PCM

In the mid nineties there was a problem with the PCM board. Something with grounding , a crack or something...there was a GM TSB on this and a repair kit too

Mayb Brisco or airworld2 remembers better than me.
 

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Trans ID for the 4L60E is located on the passenger side of the case about halfway up the trans. It is 0.5 inch tall cast in lettering. Can't miss it.
I just rebuilt my 4L60E because it was slipping in 3rd gear. Found out the 3rd gear clutch pack was fried as well as the stator shaft ID. After a complete rebuild and a few replacement parts, as well as a new internal wiring harness I took it for the initial test drive, exact same issues you are having. No 4th, no 2-1 down shift, no fault codes (I had them checked), manual shift to 1 will get 1, but not in drive mode.
Since mine is all new hardware, this should suggest the internal mechanics are OK. Looks like we have an electrical problem as a few suggest.
 

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remington7 said:
It has 16 bolts in the pan. Can't really find any identifiable markings on the case. :confused:
16 bolts would be a 4L60E trans
 

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Discussion Starter · #11 ·
With no previous transmission problems, I was on a recent trip and I noticed the rpm on my tach was running about 2500 rpm at 60mph in overdrive (normally runs in the 1700-1800 rpm range at this speed). I manually downshifted to 3rd gear then back to overdrive but rpm remained at 2500. I continued at this pace for about 6 miles to a local Wal-Mart so I could check the transmission fluid and in case I needed to purchase some Dexron. Coming to a stop at my exit, I noticed the transmission did not drop down to 1st gear. When I accelerated, it was still in 2nd gear and slow to move. The passing (kickdown) gear was not operational either. At Wal-Mart, the fluid level was fine and had a nice pink color with no burned smell so I made no additions. Upon leaving Wal-Mart, I shifted manually to 1st gear to see if was working and it was. I then manually shifted up to OD (at highway speed) but the transmission would only go to 3rd gear. On the drive home, I left it in OD to see if there were any changes. No changes at all. So I have a 4L60E in a 1995 Chevrolet K2500 P/U(6-lug) with 95,000 on the clock. Overdrive is not working at all, 3rd and 2nd gears are fine, 1st gear works fine only if shifted manually from a stop. Please HELP!

Based on my original post above, I am a bit befuzzled :confused: as to the trouble code I pulled from the ECM diagnostics. I received a DTC 66 code which according to my Chilton's is a 3-2 Control Solenoid Circuit fault. I was having trouble with OD and 1st gear. Would the 3-2 Solenoid cause the OD/1st gear problem I described? Thanks.
 

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Check this out... 1st gear- solenoid A is on, Solenoid B is off
2nd gear- sol. A is off, Sol. B is off
3rd gear- Sol. A is off, Sol. B is on
4th gear- Sol. A is on, Sol. B is on

So you can see that in first and 4th, solenoid A has to be on to accomplish the shift. I think solenoid A needs to be replaced.
 

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briscoe said:
Check this out... 1st gear- solenoid A is on, Solenoid B is off
2nd gear- sol. A is off, Sol. B is off
3rd gear- Sol. A is off, Sol. B is on
4th gear- Sol. A is on, Sol. B is on

So you can see that in first and 4th, solenoid A has to be on to accomplish the shift. I think solenoid A needs to be replaced.

Did we determine that this is a 4L80E trans?


:cool:
 

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Discussion Starter · #14 ·
Sorry about that, it is a 4L60E (stamped M30 on case) with the 16-bolt pan. The solenoid on/off analysis seems right, but if I were to purchase a "Solenoid A" at my local auto parts store, which solenoid would I ask for? The reason I ask is that AutoZone, Advance, or NAPA do not list a "Solenoid A" for a 4L60E transmission. Would it be called by another name? Thanks.

:thumbup:
 

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4l60e

Well, with 95,000 miles on the unit, if you pull the pan to change a shift solenoid, you may want to change both shift solenoids.

They are the same, so if you ask for two shift solenoids you can't go wrong.

Just throwing parts at a trans, in hopes of fixing it, sometimes does not work out, but if your vehicle was in a trans shop there is a multitude of tests that could be run.

Most require expensive test equipment that wouldn't be practical for anyone, other than a shop to own.

The solenoids are cheap enough, it's either this or off to a shop you go!

A quick word about your 3-2 solenoid error. It is possible that these symptoms your truck is displaying, could induce this code. It is also possible the 3-2 downshift solenoid is bad also.

Analyzing the shift solenoid sequence, it seems very likely the A shift solenoid could be the only culprit, however, I don't like fluid dripping on my head, so I may be inclined to change that sucker also. Please let us know how it turns out.
 

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Discussion Starter · #16 ·
Having never dealt with a local transmission shop, I'm not sure which direction to go. Word of mouth around these parts is like forecasting the weather, 50/50 chance of anything ;) . I'll have to do some searching for a reliable, reputable transmission shop in my area. I think my AAA membership offers a mechanic recommendation service at no charge. I'll try that and see where it leads. I'll let you know what I find out. Thanks.
 

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Discussion Starter · #17 ·
Hello all,
I changed out the A & B shift solenoids yesterday and the problem is still there. I'll get an appointment with a shop for a transmission scan. An earlier post said something about a GM tech bulletin for the ignition switch possibly causig this problem. Does anyone have a link to this bulletin? Thanks
 

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Discussion Starter · #20 ·
Thanks for all the helpful suggestions. I got the truck into a local repair shop and the tranny was in poor health. They're doing a rebuild and I also had a leaking seal on the transfer (I saw this when I put in the solenoids). DOes anyone know the warranty period on new GM transmissions? Thanks again.
 
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