Outcastz89

Hey everyone. Alright, here's the story. I got a 1992 Silverado 1500 4X4 with a (5.0L) 305 and a 700R4 transmission. The transmission has about 3500 miles on it. It was rebuilt not to long ago for a plow truck in Michigan and had all the upgrades installed in it as well as a shift kit. Before I got the transmission it had about 1500 miles on it, never did see a plow or snow even. The former owner decided to part out his plow truck after he got it done with it and the engine threw a main bearing. When I put it in at the shop, I put a new filter in, flushed the tranny cooler lines and filled her up with new fluid. She's driven more than fine til' Thursday night. I was on my way home from the shop, when all of the sudden I lose every gear except 1st, 2nd, and reverse. I didn't hear any odd noises, there is no check engine light. She shift fine from 1st to 2nd, when she gets up to the proper RPMs to shift into 3rd it's like she goes into neutral. So I check out Alldata last night. The closest thing I came come up with at the moment, is either the input speed sensor, or the output speed sensor. I brought her down to the shop yesterday when I went to work. I'm going in tomorrow to check the connectors and wiring for the speed sensors. Alldata says that after 1st and 2nd gear it uses those sensors to shift through the other gears. I'm thinking it's kind of like a fail safe mode. I have already checked my tranny fluid and that's up to spec and there are no exterior leaks on the transmission.

My main question is there a way I can test these sensors that anyone knows of? Alldata doesn't show any kind of test I can preform on them. Also, does anyone have any other ideas other than those sensors or connections to the sensors that could possibly be my issue?

Thanks to everyone in advance for their comments and ideas. Sorry for such a long post.

Outcastz89

Anyone got a clue to as what's wrong with my trans?

Chevy4power

A friend of mine had a 4L60e with same problem in a 94 model. He replaced the shift silinoids behind trany pan. Now it shift's like new again.

Outcastz89

Yeah, I was kinda thinking the same thing. I'm taking it to the transmission shop tomorrow. I was thinking it was the DRAC but now I'm not really sure. I don't know a whole lot about transmissions, just basically how they work and a few other odds and ends. Thanks.

transguy37

Hello,

The 700R4 is not an electrically controlled trans, so there is not a failsafe. On the 4L60E failsafe is 3rd gear. If your trans is neutral in 3rd gear,then the 3-4 clutches are wiped out.