1996 Yukon Transmission problem

mike-patton · 02-18-2003, 10:10 AM

First off, sorry this is so lengthy, but I wanted to get everything in here so you guys had the whole story. I really need some advice on this. I have read through and searched these forums and didn't find anything that completely matched my problem, so here it is.

The other day I was driving along and got on it (the tranny dropped into second gear) to get around a car so I could get on the highway. All of a sudden the tranny dropped into first gear so I let off and as I was slowing down to pull into a parking lot to check it out I noticed that second was completely gone (like it was never there). It would rev up to about 4000 RPMs and then shift directly to third gear. It had done something simialar to this when I first bought about 2 years ago and turning it off and the back on fixed it, so that is what I tried to do. Needless to say that didn't help it. Here is the kicker though. Second gear is not the only gear gone. Every other gear I have doesn't work. Park (works), Reverse (gone), Neutral (works), OD (gone), third (works), Second (gone), First (works). I have tore up two tranny's in the past (usually second gear) and it has never just completely bypassed that gear when it went out. What is wierd is it doesn't even try to engage that gear. When I put it into reverse it does nothing, no jump like it normally would when it engaged into gear or anything like that. All the gears I noted that were bad act exactly like neutral now. Is there a sensor or switch that would cause this behavior????? I am in desperate need of some help here.

bowtiebandit · 02-18-2003, 10:40 AM

Is the Check Engine light on? Did you here any strange noises? Does 4wd work? if so do you get the same results?

mike-patton · 02-18-2003, 10:50 AM

Yes, I forgot about that. My Check Engine Light came on when this happened. I did make a slight clunking noise, but that could have been from being suddenly thrown into first gear.

mike-patton · 02-18-2003, 10:51 AM

I haven't checked 4WD yet. Let me go do that real quick.

mike-patton · 02-18-2003, 10:58 AM

Yes, 4WD works just fine. I get the same exact results in 4WD though as I do in 2WD.

Any ideas as to what it can be. I don't really think it is tranny problem (required rebuild or replacement) because it doesn't even try to use the gears that are no longer working where in the past when I had a tranny go out it would still try and use that gear but lock up when it did.

bowtiebandit · 02-18-2003, 11:15 AM

What may have happened is the PCM saw a rapid change in line pressure from the PC solenoid and went into default mode. Although I dont do transmissions I do see this alot. The Service Engine light is a clue to what may have happened. I'd see your dealer before any other damage occurs, you may try to pull the trans fuse and see if it resets itself.

mike-patton · 02-18-2003, 11:26 AM

Where is the Trans Fuse located?????

mike-patton · 02-18-2003, 11:50 AM

Well, I found the Trans Fuse and pulled and then started my Yukon. Then killed it and re-inserted the fuse. However, it didn't fix my problem. I guess I will just take it to a transmission shop.

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