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Discussion Starter #1
I recently had troubles with my Disco,while towing my 944 back from the track.
The truck went into limp mode with the flashing m&s and hasn't come back out.
I took it to land rover after being told that a common code reader or icarsoft would not
be able to clear the issue. What immediately happened when it went into limp,
was that the red indicator lights adjacent to the shifter stopped working, the lcd no
longer showed the current gear, and the car ran in 3rd(i believe) continually. It does still
run and drive, except with no shifting between gears in drive, reverse,etc. no problem. I pulled
the xyz switch and cleaned it. It is the newer style without the copper strips/wipers. I reinstalled it, and
still was not able to get any gear indication on the lcd when turning the switch. Shouldn't
I be seeing some sort of gear indication on the lcd if the switch is good??? Why no red
lights on the indicator near the shifter? I noticed a lead was corroded clean off of what
appeared to be a sensor on the driver side of the tranny near the back. If this was a short,
or if it is not connected(its not) would this be connected to my issue? I plan to change the
tranny fluid and filter. Will this potentially have an effect on the codes if the fluid is low?
Is there some way to reset the computer, clear these m&s lights, and start fresh??
Something similar to "flashing" an ecu?...hard reset???

Thanks,
Giltgy
 

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if you took it to LR, what did they say?

any LR friendly scanner should be able to query the computers and pull codes, and clear them.

if you disconnect + and - from your battery, and short the VEHICLE side + and - (NOT THE BATTERY SIDE (-;) for a few minutes, that will completely discharge all capacitors and effectively reset the vehicle
 

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The ''hard reset" might have a certain effect only for the engine ECU, albeit i doubt that it would be for any use on a D2 nor that stored fault codes would be erased just like that... though it's completely irrelevant for the transmission ECU which has no direct battery feed so while the ignition is off it's ''isolated'' if you see hat i mean. A dedicated tester is compulsory
 

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Discussion Starter #4
Codes

codes that showed up at LR were Airbag, evapP0455, Solenoid valve lockupP743 and Position
switch monitoring. These reappeared when they cleared them.

Hopefully this is fixable, as I really like this rig, and am hopeful that it will continue to rack up
miles.....it now is at 199K!?!?!

Best,
Giltgy
 

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according to my D2 shop manual, "The gear position switch outputs are monitored by the BCU and the EAT ECU. The BCU outputs gear position signals to illuminate the position indicators each side of the gear selector lever and on the odometer LCD in the instrument pack."

Check connections at BCU and TCU, and potentially test the runs between.

you said you cleaned/checked the XYZ switch, but did you test the leads for voltage?

P0743 (7, 25)
* Torque converter lock-up solenoid (MV 3), open or short circuit
Limp home mode in low and high ranges. Shift pressure to maximum, harsh gear shifts/ engagement.
MIL and S/M = ON

What was the "position switch" code?

if you need the shop manual, PM me your email and i'll send it over
 

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Discussion Starter #6
I am still trying .......replaced the TCU and xyz switch. There are still no gear
indicator lights next to the shifter or on the dash. The next will be the BCU.
Does this require some elaborate reflash??? The dealer said "new transmission"
I have a hard time seeing that, and am considering dropping the pan and
valve body and replacing the bad solenoid if I can hopefully get the replacement
part. Is this something anyone else has experience with???
 

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Discussion Starter #7
The Disco does everything, starts, drives, but does not shift, and
is stuck in limp, in 3rd gear. If I fix what is wrong, will it stay in limp
for "40!?!?" trips before it clears out the limp mode, and drives normal?
 

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what were your findings when testing the XYZ sw?

do you have an LR specific scan tool? if you're going to play "parts darts" with it, it would be very helpful to clear/reset everything after an attempted repair and see what comes back.
it would be ideal to clear all codes and then test the XYZ, because it may be sending accurate data to the BCU, but the BCU may not care because of a stored fault.
 

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Discussion Starter #9
I am really not sure how to test the xyz(out of the car). I will
use my icarsoft scan tool. I am not sure if this will do it, and when
i tryed with it initially it said it was not able to communicate with the
transmission for some reason. Since i have now replaced the TCU and
the xyz switch with reportedly good units, I will try again. I will let you know
my results.

Thanks,
Giltgy
 

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Have you checked the battery and alternator connections and output? Low voltage (.5-1V) can start tote truck in a stupid way.

I will dig up the electrical connections for the XYZ switch. It’s possible that your new (and old) microswitches work fine, but the plug or wiring is bad.

There are five microswitches inside, three of which feed signal back to your ECU. If you can start the truck then the neutral/park switches/wiring are ok. If you put the truck in R and the backup lights illuminate then that switch (and wiring is good).
 

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here are the EAT pinouts... still looking for XYZ and BCU

Screen Shot 2019-10-01 at 9.27.56 PM.jpg

Screen Shot 2019-10-01 at 9.28.32 PM.jpg
 

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It has happened to my Disco twice before.

What I have done believe or not ! I have gotten a rubber hammer and go down there and gently bang on the shifter ... last time it was so late and I wanted to get home_I used a long thick screw driver ...I worked. Try it might work for you !
 
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