Thread: Need Help diagnosing tranny problem.

Not having forward range in D or 3 sounds like a broken forward band, but that wont effect reverse operation. The fact that you lost it all at the same time sounds like you likely have a blown channel plate gasket. Some diagnostic time with a pressure gauge and scan tool to control line pressure may reveal what the problem is but otherwise you are at the mercy of having to tear the trans half way apart to investigate. There is not much you can do with these transmissions without dropping them down and removing the side cover

Thank You Trannyman.

I turned the car on today and let it run for 20 minutes. Then I shifted slowly through the gears Reverse works fine still and so does 1st and 2nd gear. Third gear and drive still do nothing.

Maybe this can help diagnose the problem. When I'm in reverse and when I put it in neutral the headlights and dashlights get dimmer and then when I move it to drive the lights come back to full brightness and the engine revs up to about 1000 rpms then settles back down, it does not do this from drive to 3rd gear.
Could this be electrical?

The next thing you can try is to drive the car by manually shifting 1-2-3-4. Now that you mention reverse working that for the most part rules out the channel plate gasket being a #1 suspect. If you can get all 4 forward speeds by manually shifting then I would definately point at the forward band being broken. This can happen any time out of the blue for no rhyme or reason. If it is in fact broken you can verify this by removing the lower pan and looking up into a windowed out section in the trans case just past the narrow end of the filter. Straight up in this area you will see where the forward band sits and there is an apply pin sticking in from the back side of the case. You will either find a broken piece of band laying in the pan in this area or you will see the band is broken and still in place. If the band is broken it means a complete overhaul as the band is literally one of the last parts to come out of the case.