Oh NO! Transmission slipping when going into SECOND!

Everything was fine and all of a sudden the tranny started shifting weird from first to second.

The shift kinda hangs for 1/2 a second and then changes.

Everything else is completely fine.

Tranny shops says it is more than likely the main pressure solenoid.

Any thoughts guys?

Sounds like you might be a candidate for the valve body mod where they overbore you a new pilot hole and insert an oversized ball valve kit. Could also be that you just have a tired solenoid. They can and do happen from time to time. I would ask about the possibility of either one being the fix needed to keep you rolling before you opt for a rebuild. And boy howdy, do they like to push a rebuild on you. Good and much luck to you my friend!

Yea, I know for sure a rebuild won't be necessary because every single other gear works fine all the time without delay.

Now figure this, I just went out and reset the computer and the delay has seemed to have gone away?

Coincidence?

Yea, I know for sure a rebuild won't be necessary because every single other gear works fine all the time without delay.

Now figure this, I just went out and reset the computer and the delay has seemed to have gone away?

Coincidence?


No actually, if/when I drive mine hard on my 99 the computer shift points are different until I shut it off and it's restored. Has to do with load/torque and then you back off, it still shifted hard until I shut it down (reboot) and it was fine again ....I will do more investigation...

I also replaced the TPS yesterday, reet the computer and went for a drive yesterday and today and the transmission is shifting completely normal now.

Go figure.

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willysjeep [sm_search.gif]
AF Newbie
Joined: Mar 2005
03-13-2005, 07:55 AM
I had a similar problem on a '96 Blazer. After 70K miles 2nd going into 3rd gear on the automatic transmission was slipping. Check GM Bulletin Number 66-71-03A. The cause may be "poor internal ground between the two circuit baords of the VCM can cause the VCM to command erratic line pressure at the pressure control solenoid."

Basically, the control solenoid wasn't working correctly due to grounding issues and it caused the bands to slip, thus trashing my transmission.

If I were you, whether this is the cause of your problem or not, install the "Harness jumper wire and instruction kit P/N 12167310". It's a little jumper wire installed on the computer right under the hood. When you re-build your transmission you will want this fix or it may happen again. The kit costs about $10. If the jumper is already installed you should see a tag around the VCM wiring harness. I only wish my dealership at the time told me this. It would have been a small price to pay if I only would have known at the time.

If memory serves me correctly, I believe the manufacturer corrected this problem at the assembly line in March or April of 1996. I believe this problem existed since the transmission was put into production in 1995.
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Could be related, the "late 1995" blazers with OBD2 sometimes show up with problems that GM says started with 1996. A good solenoid might shift ok with a weak ground, but when the solenoid gets weak the problem shows up.

We proudly make the 4L60-E pressure control solenoids here in Water Valley, Mississippi. Based on analysis of parts returned through GM's warranty system, it is very seldom our solenoid that causes a transmission failure. If the solenoid is going to fail, it will usually do it early in life due to contaminants (machining chips) that were built into the part by accident. Even this is less than a 1 in 100,000 parts problem. If you end up replacing yours, I'd be happy to test the one you pull out of your transmission and let you know how it performed relative to the specification. You can mail it to BorgWarner, Hwy 32 East, Water Valley, MS 38965, ATTN: Matt Allbert.

BlazerLT, By "reset the computer" do you mean disconnect the battery for a minute?

BlazerLT, By "reset the computer" do you mean disconnect the battery for a minute?

I turned the key to the on position and pulled both ECM fuses.

Since then, the transmission has been shifting perfectly.

My blazer has done that on 3 or 4 ocassions while getting on it since I've owned it. It will just do it 1 or 2 times then will be fine a few months and out of nowhere it will do it again. I had a tranny line come loose and after refilling all that I lost (5 quarts) it has not done it since. Maybe a coincidence, though.

I would like to replace the filter, too, but appearently there is a deep pan and a shallow pan. I don't know which one I have. Does any one know the difference?

The normal is the shallow pan and it is all that you need.

If you have a deep pan, the bottom of the pan will likely have a step where it goes from being deeper to being shallower while the shallow pan will be flat across the bottom. A deep pan also may have either a drain plug or a round depression that looks like a spot where a drain plug might have gone. The filters for the deep pan have a longer neck where they plug into the valve body so that they reach deep enough to pull up the fluid from the deeper pan. I've never heard of anyone trying to use a shallow filter in a deep pan, so I don't know how risky that is. The cost difference at AutoZone is minimal, and it's easy enough to tell the difference, so I'd just use the correct part unless someone has a good reason not to.

If you have a deep pan, the bottom of the pan will likely have a step where it goes from being deeper to being shallower while the shallow pan will be flat across the bottom. A deep pan also may have either a drain plug or a round depression that looks like a spot where a drain plug might have gone. The filters for the deep pan have a longer neck where they plug into the valve body so that they reach deep enough to pull up the fluid from the deeper pan. I've never heard of anyone trying to use a shallow filter in a deep pan, so I don't know how risky that is. The cost difference at AutoZone is minimal, and it's easy enough to tell the difference, so I'd just use the correct part unless someone has a good reason not to. Thanks, it's got a flat bottom so it's a shallow pan. I would have done it along time ago, but didn't know what the difference was.

I turned the key to the on position and pulled both ECM fuses.

Since then, the transmission has been shifting perfectly.
Interesting. thanks.