Lurked the forums since purchasing 03 Disco II on a whim a couple years ago.. and if I'd have
known then, what I know now.... anyway.
It was mistreated by the PO, and several hundred (or thousand) dollars later, most everything under the hood has been
either fixed or replaced by myself.
Stopped the running hot thing, replaced radiator, water pump, all hoses, etc..
Replaced all O2 sensors.
Replaced coil packs, alternator and wires/plugs.
Cam pos sensor, crank pos sensor.
Intake manifold gasket, front plate gasket, valve cover gaskets, oil pan gasket.
All fluids changed. Both axles oil changed. Transfer case oil changed.
Gas tank emissions tank and sensor, and a few other things i can't seem to remember right now.
Ok, on to the issue. (just wanted to illustrate how much work has been done so far)
Ran GREAT after the year of work done above.. then, it went into limp mode one day.
Checked all the "normal" problems that seem to fix it. Battery, cables, etc...
All of that is fine/perfect.
Took the XYZ switch off/apart, cleaned and slightly scuffed the copper contacts to ensure
proper connectivity.. fiddled with the position after reinstalling the switch,and got it to where
it would start, run, drive, etc..
Same issue.
It seems as if when trying to maintain speed/coasting, you feel the tranny disengage??
Kinda like it's slipping into neutral going 30-50 mph.
One of two ways fix this immediately after..
1. If not paying attention, with foot still on the gas, the engine will rev up to 3k-4k RPM and then the tranny kicks back into gear..
THAT causes it to go into limp mode...
2. If I slow down to say, 10-15mph, with RPMs at idle, it will engage 2nd gear (while still in drive), and
you can go on about your business.
Might do it again, might not..
Dumped trans fluid, changed filter, etc.. filled fluid, drove it a week or so,(about 200 miles I'd say), repeated
the process.. Same issue.
Adjusted XYZ switch again, thinking it might be off a hair, didn't matter.
Only thing I have yet to do at this point is change out the speed sensor tucked up inside the tranny.
Would that be the logical next step?
I'm tired of throwing money at this thing... it's getting old.
Like I say, I've looked around the different forums for this exact issue, and wasn't able to find one
acting like this.
Can anyone point me in the right direction here?
I'd sure appreciate it.

Thanks!!

 

Unless I missed it, what trouble codes are you getting?

 

Purely a guess, but given the comment about the speeds involved - 30-50, it slips then engages then limp mode.
But at low speed it re-engages and continues OK.

This sounds like the transfer case is going in and out of neutral - since you can shift the transfer case while moving (at low speed).

Just a thought - no evidence, just a "hypothesis"

 

Trouble codes.. Right. Sorry..
Here's what I pulled this afternoon..
P0301
P0442
P0722
P0741

OK, 0722 is telling me the speed sensor isn't functioning properly.
That may have just explained the problem..
P0741 - No clue on that one... related to the speed sensor maybe??

 

Yeah I was thinking speed sensor issue from what you described....quick internet search says.P0741 has something to do with the torque converter.

 

Check all your and I mean all your vacuum lines and everything attached to the throttle body intake hose. Those last 2 741/722 are often symptoms of other issues rather than the sensor or transmission. I have had the clamp holding the intake hose come loose and toss both of those codes, as well as a vacuum hose in that area.

 

Ok, thanks guys for the replies.
I'm going to order the speed sensor, go through all of the vacuum lines and check for leaks.
Has anyone had to change their speed sensor in this transmission?
If so, any good deals on price anywhere?
I've seen the range of price, pretty narrow.. and high (just like everything else)
Don't know about the #1 plug giving a foul reading.. I'll reset the errors and see what throws
again.?.?
It doesn't have a lot of miles on it, 135k abouts?
Mostly because I've had to work on it so much and it stays parked... and I'm afraid to take it anywhere
outside of 50 miles.

I'll reply with what I find/results, I HATE reading posts where someone like me asks questions and never replies..
I'll reply.





Thanks again!!