Trans slip in 1st gear...

unkleJ · March 30, 2005

Guys,

Today my transmission was acting kind of funny. To set the stage the only mods are a magnaflow catback and a MIT intake tube (paper filter). I am running the stock tune and my truck has 13,000 miles. I don't beat on the truck that often and there are only 8 runs down the 1/4 mile.

Anyway, I was almost to work (10 miles on back roads) when I got stuck at a red light for a few minutes. Then, when I went to accelerate from the light it seemed like my transmission was slipping for a few seconds (until ~15 mph) and then grabbed. It has acted normal ever since.

I remember reading about this same thing on a few boards awhile ago and it seem that a lot of people had the same problem, every once and a while the trans would slip like that. Has this happened to any of you and what did you do about it (if anything at all)?

Jeff

SS Crew · March 31, 2005

You trans isn't slipping, the trans is staying in high gear. When you take off and the truck doesn't accellerate you give it more gas. The engine lugs and downshifts. I had 125,000 on my '99 ECSB and it did that probably once every 2 months. I pulled my boat and never had a problem. Chevy could never duplicate the problem. But I did have it documented at the dealer in case something did happen in my warranty period.

Good luck!

am70043 · March 31, 2005

I had the exact condition you've described happen to me twice within the first 8 months of ownership. After the second time I dissconneted the battery over night and it has not happen again. I figured the computer was learning my driving habbits----go figure! No mods bone stock.

March 31, 2005

My truck did the same thing last night on the way home. It has happened about four times in 40K miles and always catches you by surprise so you can't remember exactly what happened. Thanks for the info SS Crew. I think I'll sleep a little better now.

BADGERMAN · March 31, 2005

I have also had that happen and the dealer couldn't get it happen to them.

They told me it was the fan clutch engaging and disengaging. IMO thats a bunch of

It really happens bad on cold mornings. It's almost like it can't figure out what gear to be in.

Bish · March 31, 2005

This has happened to me about 6-8 times in 135K. Happened under warranty and got the old "unable to duplicate" from the dealer. It definitely is in 2nd gear when it happens (while stopped) and then it downshifts with a slight bang. After the first time, I could recognize the other times it happened and went easy on the gas and it took away the bang.

Haven't had any tranny problems other than this problem in over 135K so I don't think it is doing any damage.

unkleJ · April 1, 2005

Wow, I guess I'm not alone. Thanks for the replies. This is something I found on LS1tech... I think this sounds like what is going on.

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Intermittent Neutral from a Stop or 2-3 Shift - kw flare information launch slip #PIP3002C - (Sep 22, 2004)

4L60E/4L65E Intermittent Neutral from a Stop or 2-3 Shift

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The following diagnosis might be helpful if the vehicle exhibits the described symptoms in the PI.

Condition/Concern:

The 4L60E/4L65E may experience an intermittent neutral condition while accelerating from a stop (category one) or while driving (category two).

Category One: Intermittent neutral condition occurs on accel from a stop with the shifter in D4. The neutral may be associated with an engine flare and then a harsh engagement. The Transmission Fluid Pressure Switch should read correct signal "A" High "B" Low "C" Low.

Category Two: Intermittent neutral occurs during 2-3 shift and the transmission will not have 3rd or 4th gear. The "B" Shift Solenoid is not bleeding off during the 2-3 shift allowing the transmission to stay in 2nd gear and return to first during the 3-4 shift.

Recommendation/Instructions:

Category One:

Attempt to duplicate the condition and if possible capture a snap shot of the condition with the Tech 2 or VDR while monitoring the transmission line pressure with a gauge. The following should be monitored to ensure the PCM is not commanding a higher then first gear start.

The Transmission Fluid Pressure Switch. The correct reading for D4 is as follows "A" High "B" Low "C" Low.

VSS should be monitored at stop to ensure that it is reading 0 MPH/RPM

Commanded Gear should be first Solenoid Status "A" on "B" on

Engine cooling fan operation should be noted and discussed (TSB 01-06-04-052, 02 Trailblazer, Envoy Bravada with 4.2 engine) Transmission line pressure low during the condition may cause an intermittent loss of pressure and neutral condition. Some customers may describe a launch in a higher then first gear as a neutral due to the greater amount of engine noise associated with the launch and lack of acceleration. In the event the dealer is unable to duplicate the condition, the dealer may consider installing an entire transmission shift cable, inspecting the forward clutch seal/piston and inspect for a broken or missing oil pump spring (two springs on units built 15-DEC-03 or earlier, one spring on units built 16-DEC-03 or later, reference bulletin 04-07-30-006)

Installing Transmission Assemblies, Lo Roller and the Forward Sprag have not been proven to be an effective repair.

Category Two:

Attempt to duplicate the condition. The "B" Shift Solenoid should be air checked for being restricted and not exhausting. However air testing the solenoid may remove the restriction. The "B" Shift Solenoid should be replaced.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance

Markeaux · April 1, 2005

This is something I found on LS1tech... I think this sounds like what is going on.

That's not the same thing as what you originally described since you said you got up to 15mph before it dropped down ... that tech note only describes flaring in neutral then dropping in gear ... Anyway yes the the very intermittent 2nd gear start happened to me about 6x, seems to be a common complaint.

It seemed to happen the most when going pretty fast, coming to complete stop, then quickly taking off again. I had my PCM flashed with the latest updates a couple years go but I think it happened one more time ... The problem was not on the PCM fixes list at http://calid.gm.com/vci/VINEntryPre.do so I had to complain about a problem that was on the list before they would reflash under warranty.

unkleJ · April 2, 2005

Yeah... it could either be the second gear start or the trans slipping thing. It has only happened once and it happened so quickly that I'm unsure on all of the fine details. Anyway, thanks for your help.

Jeff

budone · April 2, 2005

This happened just yesterday to me. I took it to the dealer and no codes, up to date software and 'Never heard of it before'.

Only 3700k on my truck.

100R1 · April 2, 2005

Perhaps a sticking solenoid or sticking valve

even could be debris in the valve body/ spacer plate

Under warrenty take it back to the dealer, I would tell them it has happened more than once to get more attention. Let them make sure that your PCM has all of the current "FLASHES". Updating to current flashes has solved some other owners tranny driveability problems.

I would also change the Tranny fluid & filter. New fluid would have better cleaning qualities than old fluid and could help flush out any debris causing sticking parts.

Make sure you get the latest Dexron fluid specification Dexron III-H. This Spec. is far superior to the older DIII-G with newer additive packages and longer fluid life this may help in your driveability problem also.

If it only happens once more than likely no big deal, but if it starts to occur more often it can only get worse.