Transmission woes

[1987_345]

Just got back from our longest trip yet. 425 miles one way up to beautiful Ouchita State Park in Arkansas. Pulled back into our home town and gassed back up so as not to leave the tank empty and forming condensation while it sits for awhile. Pulled out of the gas station only to find I had no 2nd or 3rd gear!!! Got it home in first, high range, and checked the trans fluid. Full to the level, no bad or burnt smell, no leaks, not hot or smoking either. Checked the vacuum hose down to the trans, and its fine as well. Coach gave absolutley no trouble on the trip, but gets me home really scratching my head. Any ideas on where I should start looking for a problem? Oh yeah. Original 1987 345 trans with 36,000 miles

[lahrfarm]

I had the exact thing happen to a pickup, and I mean exactly to your description. I found it to be a large snap ring, I guess you'd call it, that held the higher gear clutches on the shaft in the transmission. I dont really know what all the parts are called I had someone do the work. The trany was completely aprart to find this out, so we rebuilt the whole thing. If it would have been a standard I'd have done the work, but I'm not sure about an automatic. This may not be your problem, but they sound the same.

[Delaware]

I had a similar experience with my 350LE. It turned out not to be the transmission but the ECM or Electronic Control Module. When the ECM fails the vehicle goes into a "Fail Safe" mode [also called the limp home mode]. You are limited to first gear. You may want to check this first as it's less expensive then a transmission rebuild. Good Luck.

[au_ee]

Had a similar problem with a Winnebago Brave with a Chevy chassis. We were going down the interstate and the transmission shifts down and would only operate in low gear (safe mode). We located a dealer and after testing the transmission they found a shift transducer had gone bad. They went ahead and replace both, just to be on the safe side, and we were on our way. On the chevy tansmission these are accessible from outside the transmission housing and didn't take long to repair.

[ibgl6]

I had that happen just a couple months ago in a 99 1/2 ton surburban it was the ignition switch located on the lower end of the steering wheel. Was told not geting proper power to the electric shift thingy's for the transmission to shift been working fine since....SAM

[1987_345]

Finally got around to fixing it. It turned out to be the nylon gear on the shift control module. I guess the age of it was more than it could bear. It had just crumbled. I would suggest replacing it at your earliest convenience. It was a little hard to locate one, but an easy replacement.

[John H.]

Originally Posted by 1987_345

Finally got around to fixing it. It turned out to be the nylon gear on the shift control module. I guess the age of it was more than it could bear. It had just crumbled. I would suggest replacing it at your earliest convenience. It was a little hard to locate one, but an easy replacement.

do you have a Chevy Part Number ?

[1987_345]

Let me see if I can find it for you when I get home tonight. I searched transmission shops all over town to no avail and ended up urdering it online from a vintage type supplier