Transmission won't shift past 2nd gear (most of the time)

[Shuck]

I've got kind of an odd one on my hands here and I could use some expert advice.

My truck is a 95 K1500 (L56) 6.5 TD with just under 200k on it.

On my last long trip, we had trouble with the transmission "falling" out of drive and overdrive. Checked the fluid and it was low, so I added some and it seemed to fix the problem. Well, it came back further down the road. Fluid level was fine, but it was late at night, so I pressed on. I could tell if the transmission was going to work or not by watching the shift indicator light and tach/speedo on the dash. If the transmission wasn't going to hold D/OD, the tach would drop to 0 and the speedo would slowly creep up and the shift indicator light would go out.

So i figured maybe the D/OD solenoid was going out. BUT then I drove along for a while and boom, gauges came back and transmission worked fine. Same thing the next morning. Started it up, no tach, weird speedo, but after driving for about 15 minutes, gauges came back and the transmission worked.

So, I haven't had much time with the truck the last two weeks, but I figured one more thing out. I have a remote start on my truck and just for kicks, I engaged it while driving down the road. When I engaged the remote start, the transmission worked fine and the gauges came back to life.

Is there a signal from a switch on the ignition that might be causing my problem? Should I plan on having to replace the D/OC solenoids in the transmission? How big of a job is that? Any help is greatly appreciated as I'd like to have the truck fixed to drive home for Christmas in 3 weeks (about 1000 miles).

Thanks!
Ryan

[patrick m.]

being a 95 model, i would suspect ignition switch. There are multiple power feeds to the fuse panel from the switch. When this switch fails, one of those power feeds gets poor contact inside the switch causing lower voltage to a row of fuses.

you can verify this with a volt meter measuring voltage at the trans fuse. Measure with the switch in every position, and while turnning the switch from off, to crank, and back to run.
Any voltage drop below 9.5 volts is trouble.

[ZZ]

Did you ever figure this out? It could've been in what they call "limp mode"

[Shuck]

Yes, I did get this fixed. I replaced the ignition switch. Before doing that, Idid try just resetting the PCM. It got it out of limp mode, but still didn't fix the dash / intermittent OD problem.

I ran into two problems while doing this switch. One was that you need and E4 inverse Torx socket to remove the two bolts that hold the switch on. You also need an E5 socket to remove the top of the steering column.

The other problem I ran into was that you need to actually cut a slit in the top piece of the column around the keyhole to avoid having to pull the column and remove the lock cylinder. I used an exacto knife and cut a straight line and you can't even tell it now that I put it back together.

I had another thread going on this and received some great help in there.

Thanks for all the help!

[DA BIG ONE]

I my thread the Tahoe for hell, I mentioned I had changed out the switch only to find the fix short lived. Shops are baffled and want big $$$$ to keep truck and try to figure the problem. So, we just disconnect the battery for now to reset, then get to the next failure then do it again, surely a PITA.

Tranny problems w/randum codes all over the place, then sometimes a driveability issue again w/randum codes all over the place.

I now believe it is a heat related ecm issue (like the main chip overheating), simply because the tahoe will run perfect, getting high 20's mpg then crap on itself randomally.....

This week a rebuilt ecm install is on list.