My wife mentioned that the last couple of times she was driving to work it felt like the transmission was sometimes slipping. I told her to take it anyway (a Friday) and I'd look at it over the weekend. She made it to work fine, but when she started it up to go home that evening, it wouldn't move. I grabbed the car hauler and took a 40-minute drive to meet her and sure enough - nothing. I tried every gear and shifted into low as well just in case. I hauled it home, put it on the lift, and started with the codes:

P0734 - Gear 4 incorrect ratio
P0738 - Gear 3 incorrect ratio
P0741 - Torque Converter Clutch Circuit Performance or Stuck Off
P1884 - Engine Coolant Level Lamp Circuit Short to Ground

I cleared these out and checked the transmission fluid level. Nothing came out, so I started it up, ran through the gears again, kept it running, and began to fill until it dripped out per the book. Surprisingly it was about 1.5 quarts low! I screwed in the plug, let it down, and tried shifting. It went right into reverse with no hesitation. I was pretty excited at that point. However, hope faded quickly when none of the forward gears engaged at all.

I haven't had much luck correlating these codes with a no-shift condition. Does anyone have an educated guess on what's gone wrong? Cooked transmission? Torque Converter? Gearbox speed sensor? Stuck Solenoid?

What would be the logical next steps to diagnose the issue?

On the upside, shortly after this happened a few months back, I found a wonderfully maintained 2006 RR HSE which is what she really wanted. I'm just trying to save the Disco at this point so someone can drive it a while longer before it heads off to the great car lot in the sky.

Thanks!

 

Based on the RAVE I suspect your Torque convertor, but you should get the M&S lights. You could try 3rd gear that is the default for limp home when you have electrical issues, if that fails I would bet on a mechanical failure.

 

Thanks. Unfortunately, 3rd isn't working (along with all other forward gears). M&S lights have never come on.

Can the torque converter go bad while reverse still functions?

 

I had one other thought did you run the gears while filling, you fill until it starts to dribble then run through each of the gears and hold each for about 3 seconds then add more fluid until it does not take any more.

So I did a little more reading, it can be quite a few things which is a pain. Fluid pump could be shot along with some other blockages, which can prevent anything but reverse being able to function. There is a test you can try that may or may not help.

• Start your Disco and let get to normal operating temp
• Bring your RPM up above idle try 800-1000 RPM I would suggest in steps
• FOOT ON THE BRAKE
• Shift from park to drive or 3rd.
• With a bit of luck it will engage or at least feel like it
• Then let the Disco idle for a minute or 2 and try again
• If you get nothing in after 3 tries pretty needs someone very familiar with auto trans help you

Do not go nuts with this you can do driveline damage, say if you try at 2000 + the idea is to get the pump rotating faster to build more pressure 1000 to 1500 is more than enough.

 

Likely the forward clutch is gone, common problem with the 4HP22. If it moves in reverse it is not the torque converter. About $80 in parts to fix, or you can get a working used one for around $300.

 

Yeah, probably toast...if it had been run that low on fluid.

 

Running low on fluid once or twice does not ruin the 4HP22, the pump cavitates first and there is no pressure on the clutch to ruin it. It is more an issue with long term wear and abuse.