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Transmission fault limited gears u0402-94
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johnhorgan
 


Member Since: 23 Sep 2019
Location: Richmond
Posts: 117

New Zealand 2006 Discovery 3 TDV6 Base 7 Seat Auto Siberian SilverDiscovery 3
Transmission fault limited gears u0402-94

Hopefully someone can help me with my transmission fault.
Transmission fault limited gears available appears on dash sometimes it takes 10 or 20 miles, sometimes much less.
The car drives as if it cannot properly change up into the next gear. The revs drop as it tries to change, then go back up again, whilst staying in the same gear.
Also if I drive in sport mode it sometimes looses all gears, until I put the lever back into drive.
Normally when you move the shifter from drive across to sport mode the D on the dashboard changes to Sport and shows the gear selected. However when playing up the dash goes from displaying D to not displaying anything at all in Sport mode.
Along with this fault code U0402-94 invalid data from transmission control module. I dont know if this is related to the limited gears fault or not.
The iid tool I have does not recognise the transmission in live data or ecu info. I tried the iid tool on another vehicle and it recognised the transmission so I presume the iid tool is working correctly.
Thanks John.
  
Post #223034916th May 2021 7:51 am
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aja4x4
 


Member Since: 14 Apr 2019
Location: Westbury
Posts: 2459

United Kingdom 2005 Discovery 3 TDV6 SE Auto Zambezi SilverDiscovery 3

The fact the lld is not comunicating with the transmission would lead me to think its a bad conection somewhere.
I would start by checking the wiring plug on the gearbox and the wiring plugs behind and under the battery.
 Andrew

D3 2.7tdv6 2005
D4 3.0 SDV6 Commercial died and gone to LR heaven
D5 3.0 SDV6 HSE 
 
Post #223038716th May 2021 9:53 am
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Pete K
 


Member Since: 15 Jan 2016
Location: GL
Posts: 10336

England 2005 Discovery 3 TDV6 HSE Auto Rimini RedDiscovery 3

yeah check the wiring, particularly the twisted yellow CAN wires.

Don't rule out a fault with power and ground connections
  
Post #223041316th May 2021 11:39 am
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johnhorgan
 


Member Since: 23 Sep 2019
Location: Richmond
Posts: 117

New Zealand 2006 Discovery 3 TDV6 Base 7 Seat Auto Siberian SilverDiscovery 3

Aja4x4 and Pete K
Thanks I have checked the plug on the transmission, the pins are all looking good and lined up when plugged in. Can you tell me which pins to check for voltage / earth, and ignition status ?
Can you explain how to test/check can wires ?
(On the gearbox plug and on the transfer box)
Are there any other plugs to check behind the battery or anywhere else.
John.
  
Post #223053516th May 2021 8:13 pm
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johnhorgan
 


Member Since: 23 Sep 2019
Location: Richmond
Posts: 117

New Zealand 2006 Discovery 3 TDV6 Base 7 Seat Auto Siberian SilverDiscovery 3

I meant gearbox plug and transfer case control unit plug.
  
Post #223054816th May 2021 9:17 pm
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Pete K
 


Member Since: 15 Jan 2016
Location: GL
Posts: 10336

England 2005 Discovery 3 TDV6 HSE Auto Rimini RedDiscovery 3

Check to see the wire insulation has any lumps in it.

purple with stripe +
green/white IGNITION (same colour is also diagnostic !!)
black -
  
Post #223065917th May 2021 11:17 am
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johnhorgan
 


Member Since: 23 Sep 2019
Location: Richmond
Posts: 117

New Zealand 2006 Discovery 3 TDV6 Base 7 Seat Auto Siberian SilverDiscovery 3

I have checked continuity on each wire between each end of the transmission control unit plug (gearbox end and under battery). All wires have continuity and look in good condition- no lumps or anything.
I took apart all the other connections around the battery, transfer case module and engine control module and cleaned them with contact cleaner.
Since reassembly the vehicle is driving better, it now says "GEARBOX FAULT" periodically, (previously it said "TRANSMISSION FAULT LIMITED GEARS"), but is driving almost normally. Sometimes after the gearbox fault light chimes it no longer has 6th gear, so if doing 60mph and the light comes on it will change down to 5th even in automatic mode, whilst driving normally and changing gear at slower speeds, regardless.
All of the connections looked clean and in good condition, even before using contact cleaner.
The iid tool still cannot see the transmission control unit.
Any ideas what to look at next?
John.
  
Post #223122119th May 2021 6:18 pm
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Pete K
 


Member Since: 15 Jan 2016
Location: GL
Posts: 10336

England 2005 Discovery 3 TDV6 HSE Auto Rimini RedDiscovery 3

I'd suspect a mechanical fault with the gearbox (cracked drum)
but its odd you still have comms problems. Worth sorting out first.
  
Post #223122319th May 2021 7:03 pm
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johnhorgan
 


Member Since: 23 Sep 2019
Location: Richmond
Posts: 117

New Zealand 2006 Discovery 3 TDV6 Base 7 Seat Auto Siberian SilverDiscovery 3

Click image to enlarge

Click image to enlarge

The only weird thing I could see was the 11.35 volts reading from the obd2 plug number 9 terminal.
Do you have any suggestions?
Second pic is from the gearbox transmission control module plug.
Regards John.
  
Post #223151521st May 2021 8:04 am
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Pete K
 


Member Since: 15 Jan 2016
Location: GL
Posts: 10336

England 2005 Discovery 3 TDV6 HSE Auto Rimini RedDiscovery 3

what is the first pic ?

Did you confirm you had an ignitiion supply at the gearbox ?
  
Post #223156621st May 2021 10:30 am
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johnhorgan
 


Member Since: 23 Sep 2019
Location: Richmond
Posts: 117

New Zealand 2006 Discovery 3 TDV6 Base 7 Seat Auto Siberian SilverDiscovery 3

First pic is the obd2 plug.
Yes I did confirm battery voltage to the gearbox at pin 9 the ignition supply red wire. Although there was only 11.35 volts at the red wire pin 9 at the obd2 plug. However everything seems to work through the obd2 plug, apart from no transmission ecu listed anywhere. It does not show it even to as not fitted, no mention.
  
Post #223166221st May 2021 6:32 pm
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johnhorgan
 


Member Since: 23 Sep 2019
Location: Richmond
Posts: 117

New Zealand 2006 Discovery 3 TDV6 Base 7 Seat Auto Siberian SilverDiscovery 3

Finally figured out the problem, I eventually managed to find transmission ecu.
I must have been pressing the wrong buttons or something just as stupid !
I went to tool config, find ecus and it appeared !
John.
  
Post #223170122nd May 2021 12:55 am
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aja4x4
 


Member Since: 14 Apr 2019
Location: Westbury
Posts: 2459

United Kingdom 2005 Discovery 3 TDV6 SE Auto Zambezi SilverDiscovery 3

Thats good but are there any fault codes relating to your issue?
 Andrew

D3 2.7tdv6 2005
D4 3.0 SDV6 Commercial died and gone to LR heaven
D5 3.0 SDV6 HSE 
 
Post #223170922nd May 2021 6:54 am
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johnhorgan
 


Member Since: 23 Sep 2019
Location: Richmond
Posts: 117

New Zealand 2006 Discovery 3 TDV6 Base 7 Seat Auto Siberian SilverDiscovery 3

Yes there is P0741 Torque converter clutch solenoid circuit performance or stuck off.
I had problems previously with revs fluctuating by a few hundred rpms, when at 60mph on a constant throttle, and when going uphill at 30 mph on a constant throttle.
There were no fault codes listed for this problem.
I sent the torque converter away to be reconditioned.
I rebuilt the gearbox changing clutches and bushes and rubber seals.
I ordered solenoids as well but they had not arrived.
I suspected the 4th 5th and 6th gear solenoid playing up, so I swopped it with the solenoid next to it, the torque converter clutch solenoid.
When I test drove the vehicle after reassembly the rev counter fluctuation had disappeared.
That was when the torque converter clutch solenoid P0741 reared its head.
Now I have replacement solenoids, hopefully changing them will cure the torque converter clutch P0741 problem.
  
Post #223177322nd May 2021 6:05 pm
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johnhorgan
 


Member Since: 23 Sep 2019
Location: Richmond
Posts: 117

New Zealand 2006 Discovery 3 TDV6 Base 7 Seat Auto Siberian SilverDiscovery 3

My new set of solenoids finally arrived.
Thankfully fitting them resolved all of the gearbox problems.
  
Post #22340744th Jun 2021 12:33 am
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