Suburban wouldn't shift out of second gear temporarily

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South VA

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Pulliing a camping trailer, using third gear, I stopped at a stoplight, and then went up a steep incline over a bridge. It started fine, shifted into second, and then ... no more shifts. Fortunately traffic wasn't heavy, and I managed 40mph, at about 3000 rpm. Saw a truck repair place and pulled in. Wrong type of truck, however, but they were friendly and sent me about a mile back to the Chevy dealer I'd passed on the way. When I started it up to leave and pulled into traffic, it shifted normally. I went to the dealer anyway, and the helpful guy at the service counter came out and checked the fluid level, color, and gave it a sniff. He said everything appeared to be normal. I'd just had the transmission flushed, and he said a solenoid might have stuck open, possibly due to loose debris.
In the process he also noticed a leaking air conditioning cycle valve, and suggested I replace it at the soonest opportunity, since they didn't have the part there. I've since ordered one.
Back on the road for another 60 miles and no further problems.

I asked at the shop where I take the Burb for work and the mechanic said that what the service guy told me sounded correct.

I'm wondering if this is going to crop up again, or was it a one-off thing? Anybody else experienced this problem?
 

Erik the Awful

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What year and model? From your signature, your '93 probably has a 4L60E and your '96 probably has a 4L80E. I'll guess your '93?

I doubt this is a problem that happens once and disappears. If you feel froggy, drop your pan, change your filter, and check the condition of your transmission's internal wiring harness.
 

Schurkey

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WHAT VEHICLE??? What transmission?

Pulling a trailer over a steep incline?
First Guess: Trans went into limp mode based on fluid temp or some other perceived problem. Shifting and TCC locked-out, trans operates in whatever gear is achieved by having all the shift solenoids turned "off". I'm too lazy to look 'em up, I'm thinking that 4L60E is different than 4L80E, one limps in 2nd, the other limps in 3rd.
 

South VA

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I talked with a transmission specialist, and he said it sounded like the 2-3 shift solenoid was acting up. What would cause that he didn't say. But he said that if I'm going to replace it, which is apparently a pretty easy job, to use the GM part, rather than aftermarket. He doesn't like to install the aftermarket solenoids as in his experience they tend to fail, for some reason. He also mentioned that the GM solenoid (2423089) is no longer available, anywhere. I searched and confirmed that it is not available. I found that AC Delco has a part with the same number, and I'm wondering if it works as well. Interestingly enough, the GM 1-2 shift solenoid (2430288) is available, for some reason

I'm not sure what to do, at this point. The problem didn't recur on the remainder of the trip, nor has it recurred in the limited amount of driving without the trailer since.
 

South VA

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The problem reoccurred on our last camping trip. At one point it wouldn't shift out of second, and a couple of times it wouldn't shift out of third into OD. Temporarily fixed it by pulling over and shutting it off, then starting again. Also, it shifted hard, but not consistently so. I called the transmission guy back and he said that bad solenoids would cause both issues. I ordered a GM solenoid from Rock and a Delco from Jegs, which is on backorder, so we'll see when that one arrives. The guy said it would take an hour or so to do the job, including cool-down time for the transmission. He said he could do it while I wait, which is great because it's a 45 minute drive to his shop.

I'm hopeful that that will fix it. If it does, it will be a relatively cheap and simple fix. I'll post the followup here when it's done.
 

tayto

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it's the ignition switch, very common problem. a bad shift solenoid will not cause a hard shift, it just won't shift at all. your truck is losing power to the transmission and is going into limphome mode thats why its not shifting out of 2nd (both shift solenoids off) and shifting hard (default to full line pressure).
 

South VA

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it's the ignition switch, very common problem. a bad shift solenoid will not cause a hard shift, it just won't shift at all. your truck is losing power to the transmission and is going into limphome mode thats why its not shifting out of 2nd (both shift solenoids off) and shifting hard (default to full line pressure).
I’m trying to wrap my mind around how they are connected, but if it’s a common problem , I suppose it wouldn’t hurt to replace the ignition switch.

I’m also having an intermittent charging system issue where the voltage will drop a bit after it’s warmed up. The alternator and associated wires have been replaced. Now I’m wondering if the switch could be affecting that as well.
 

South VA

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Can't find a Delco switch so I ordered an aftermarket version from RockAuto. It'll be here on the 15th. I'll hold off doing more until I have it installed.
 
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