Hello all,

I have a 2004 FX4 SCREW. When in reverse, if there's too much load, then it doesn't seem like the transmission wants to grab. I just got this truck and went out to the dunes to test it out. Well, I didn't make it all the way up one dune, so I put it in reverse. I pushed on the gas and my engine RPM went up to about 1800 or so, but nothing was happening. Well, so then I put some more throttle into it, then the RPM shot up to 3000RPM, but still nothing. The "TRANS FAULT" light and message came up, and I figured, "Crap, the transmission's slipping."

Well, I turned off the truck, figuring perhaps the transmission got too hot or something. I opened up the hood, felt the cooler, and it wasn't too hot at all. Checked the ATF, didn't smell burnt or anything. So, a few minutes later, I start the engine, try to back up, and I'm out of there pretty easy. At that point I headed home. The trans fault light had gone away when I had restarted the truck, but then I got an SES. Had the codes read, there was a P0720 (Output speed sensor circuit malfunction), and a P2106 (Throttle actuator control system forced limited power). Well, they cleared and never came back, so I figure they came on due to the fact that the engine RPM went high and the drivetrain wasn't rotating at all when I was trying to back off that dune.

So later on, I notice that when I'm reversing, say in a parking lot or whatever, I have to be real ginger on the throttle for the transmission to grab properly and back up. If I push on it too hard, then either the RPMs will go a little high (2200RPM?) before engaging, and/or it feels like the transmission engages and disengages gear intermittently. Kinda like if you were to drive a manual transmission vehicle and push the clutch in and out repeatedly.

Well, I decided to go hit some hills and check this out. So I went midway up a hill, got into reverse, hit the throttle, and it happened again. The engine RPM shot up to about 3000RPM, but no transmission engagement. No lights this time, though. So, I decided to ease into the gas real lightly -- lo and behold, the transmission grabbed with no troubles!

At this point I think I can rule out that the bands are burned up or anything. Would this be like a valve body problem or what? I don't know entirely too much about automatic transmissions. PLEASE HELP!

Thanks everyone, in advance.

 

wow thats weird! you said when you get it to 3000 rpms and nothing happens do you mean your getting it up there and holdin it or quickly letting off? because when im driving my 02 if i get on it reall fast and let off it will pop the trany into a false nutral and rev up the engine with no foreward movement. once the rpms drop back down and i get on it normally it will go back into gear.... go figure but maybe thats what is happening to you

 

What is the hot running fluid level in the trans?
Sure your not uncovering the pickup at extreme angles?

 

No I don't really get on it hard. Just pushing the gas pretty much normally to back down a hill. It's not just that, though. Just backing out of a parking spot, it seems like whatever's supposed to lockup or whatnot is having a hard time and it makes my truck shudder.

 

The fluid reads in the DO NOT ADD range. Could it possibly be overfilled?

It's not just on hills the reverse gear is acting erratic, so I don't believe that's the case.