Transmission problems!

1971Corvette · January 28, 2015

While plowing out from yesterdays blizzard I got a bit stuck with my 2004 GMC Sierra 1500. As I usually do I started rocking the vehicle back and forth by shifting from Drive to Reverse. I definitely wasn't hammering on it while doing this - I would drive forward, hit and hold the brakes, put it in reverse and then simultaneously hit the gas and release the brake. In any case, while doing this my transmission decided to protest what it must have thought was unfair treatment. Here's what it's now doing.

When this first happened the service brakes warning light came on. Eventually they turned off and haven't been back on.
All forward gears work and drive ok. However, performance seems to be a tad more sluggish than typically (kind of like the brakes are dragging just a hair). It's possible I'm imagining this.
Neutral is not neutral. When shifting into neutral while driving down the road the truck will coast and the RPM will drop. However, when I hit the gas some power still makes it to the rear wheels because the truck surges just a bit.
Reverse is bound up. When I rev the motor the engine comes up to about 1500 RPM and simply bogs down. The wheels don't spin. No odd sounds or anything from the tranny.
Park has the same issue as reverse. When I hit the throttle the engine bogs out. Again, no odd sounds from the tranny.
In hopes of resolving this (a hail Mary pass) I drove up a steep hill (about 15% incline) and put the truck in neutral so it started coasting backward. When I hit about 5 mph I shifted into reverse. The truck simply came to a stop. So much for that idea - seemed like a good one at the time.

So, at this point I'm driving around in forward gears only and suspect I have a major issue on my hands. However, I thought I'd check here to see if anyone has any ideas on what I can check quickly before taking it to a transmission shop.

For what it's worth for the past year or so the transmission was always slow to transition from reverse into drive (about a 1.5 second delay).

I replaced the filter and fluid last year and plan to check fluid levels when I get home tonight. I did crawl under the truck last night and verified the shift linkage is working properly and that there's no snow or ice jamming anything up. After getting the truck unstuck this morning there was no visible signs that the truck had lost a bunch of transmission fluid.

So what do you guys think? Is there anything else I should check before heading to the shop, or am I completely screwed?

durandetto · January 28, 2015

I would check the shifter cable for being out of adjustment. It's not common, but you never know. Sure beats paying a trans shop to tear into it.

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txab · January 28, 2015

Plan on having it looked over by reputable, qualified trans guy.

00Silverado4x4 · January 28, 2015

Plan on having it looked over by reputable, qualified trans guy.

+1. Something has gone wrong and I personally would rather leave it to the pro's personally.

gmtech4 · January 28, 2015

+1. Something has gone wrong and I personally would rather leave it to the pro's personally.

+12,890

02suburbanZ71 · January 29, 2015

First problem is you were using a 1/2 ton to plow in a blizzard. Like others said- trans shop

1971Corvette · January 29, 2015

Hey guys, quick update. I'm not sure what happened but it appears my truck fixed itself tonight. When I got in to leave work I started it and, just on a whim, goosed the throttle a little bit while in park. It bogged down briefly and then I heard a small "ker-thunk" and the motor started revving normally. Ever since everything seems to be back to normal - reverse is working again, neutral is neutral, etc. There's still a minor delay shifting from reverse to drive but I can live with that. Needless to say I'm pretty pleased!

When I got home I finished plowing the driveway and everything was fine. I was definitely babying it though!

First problem is you were using a 1/2 ton to plow in a blizzard. Like others said- trans shop

Gotta make due with what you've got!

02suburbanZ71 · January 29, 2015

It might just be the shifter cable try to disconnect the battery and hold the 2 cables together for 30 seconds. You really need to scan for codes first

durandetto · January 29, 2015

Sounds like something was up with your shifter cable. Maybe ice packed up there not allowing to move freely.

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Colossus · January 29, 2015

When rocking the vehicle back and forth like that it is pure torture on the transmission. The fluid temp soars and that in turn causes damage. Get that old fluid out of there and new fresh fluid in as soon as you can. While you have the pan dropped it will give you a good chance to look around the pan and underside of the tranny to see how things are looking, but regardless, I strongly suggest fresh fluid. I bet after doing that it will run even better, and if not, well the transmission was near it's end anyway. Aside from the reverse issues, how is it shifting now? I believe an 03 had adaptive learning on the truck trannies/computers but am not 100% sure. if it does, you can always disconnect the battery for 30 min or so (and make sure you touch the positive and negative cables together as well before putting back on the battery) and this in most cases will put the on-board computer back into learning mode for a little while and might see an improvement in shift patterns as well. Again I am not 100% certain on an 03, but know it works on the newer trucks.

Hope this helps.

00Silverado4x4 · January 30, 2015

When rocking the vehicle back and forth like that it is pure torture on the transmission. The fluid temp soars and that in turn causes damage. Get that old fluid out of there and new fresh fluid in as soon as you can. While you have the pan dropped it will give you a good chance to look around the pan and underside of the tranny to see how things are looking, but regardless, I strongly suggest fresh fluid. I bet after doing that it will run even better, and if not, well the transmission was near it's end anyway. Aside from the reverse issues, how is it shifting now? I believe an 03 had adaptive learning on the truck trannies/computers but am not 100% sure. if it does, you can always disconnect the battery for 30 min or so (and make sure you touch the positive and negative cables together as well before putting back on the battery) and this in most cases will put the on-board computer back into learning mode for a little while and might see an improvement in shift patterns as well. Again I am not 100% certain on an 03, but know it works on the newer trucks.

Hope this helps.

I'm pretty sure '04 did not have adaptive programming in the transmissions. The trans needs to be looked at internally for damage, pan drop will not allow you to see any potential hard parts problems.