Transmission (4L80E) First and Second Gear Only

[JohnC]

Have you checked for DTC codes?

Are you sure you have first? Default behavior is 2nd gear only, all solenoids off. If the PCM detects a solenoid fault during power up, it will default to 2nd gear only and set codes.

[danbenili]

It shifts between 1st and 2nd - I've test this and verified in D and D1 and D2.

Yes - Code 87 (I replaced this solenoid - which would point to a potential wire harness issue). I'm trying to figure out how to test the speed sensors.

[Bnave95]

Hold in hand and run really Fast

[JohnC]

I suggest you try this:

Clear the code and verify it is cleared.

Start the engine and shut it down without engaging any gears. Check codes again. If you get 87 then the problem is definitely in the wiring or the power to the trans cicuit (or the solenoid). The fact that it only sets one code points to specifics to that solenoid.

If no code, try again but just engage drive, but don't move. Check again.

Lastly, try engaging reverse.

Let us know what you find.

[danbenili]

I happened to run through this procedure after clearing codes (and verifying). I ran through the gears and checked the codes while in a stationary position. Still coming up with 12 12 12 i.e. no codes. I moved it to the garage in drive before pulling the valve body, but didn't check the codes after the move. How long would I need to run it to get codes? I was surprised that I didn't get the code 87 again after running through the gears. My guess is that the codes may not show up immediately i.e. you've got to drive it for x minutes before it will log some codes?

Thanks,

Paul

[dieseldummy]

I've had the no reverse problem before... As said above your looking at hard parts most likely. In my case it was a broken low band. There were no warning signs and no debrie in the oil. I checked all the electrical and and changed the fluid to no avail.

[JohnC]

[QUOTE=danbenili]I ran through the gears and checked the codes while in a stationary position.[quote]

I assume you mean you ran the shifter through the range from 1 to OD. this will not engage any solenoids other than for first. I don't have the manuals anymore, so i don't remember which solenoid positions engage which gears. However, this seems to point to a problem with something other than the solenoid as it passes the self test which tests the elecrtrical part.

I moved it to the garage in drive before pulling the valve body, but didn't check the codes after the move. How long would I need to run it to get codes?

Only long enough for the PCM to decide there is a problem; longer than the allowed shift time.

If you didn't disconnect the batteries, the codes will still be there if they were set, although I'm thinking they probably weren't. Did you put it into reverse for any length of time during this process?

[danbenili]

Yes I ran through all gears, including reverse with no codes being set - in a stationary position. I did not recheck codes after moving Truck (my bad) and I did disconnect battery before pulling the valve body out.

I've signed up for at www.alldatadiy.com and have found some interesting troubleshooting info that should help eliminate any electrical stuff as the culprit.

I think I'm in need of a GM shop manual for the Truck. I have a Chilton manual and it is severely lacking (IMO) and the alldata does not appear to have everything the shop manual would contain.

Is the only source for the shop manual a dealer?

Thanks!

Paul

[BobND]

http://www.helminc.com/helm/Result.a...4BLH0MF01JEV90



Or, watch ebay!

[DmaxMaverick]

....I think I'm in need of a GM shop manual for the Truck. I have a Chilton manual and it is severely lacking (IMO) and the alldata does not appear to have everything the shop manual would contain....Paul

The GM shop manual won't have anything in it (except dust) you can't find at alldatadiy, but the same can't be said about the reverse. Try using the search feature. Some things are located categorically and not so easy to find. Terminology can be an issue as well.

If you already have alldata, there's no advantage to having a manual, unless you just want a bound copy. Also, if you get one off Ebay, it may not be current, and lack updated bulletins and part numbers.