M and S lights, limp mode, p0743

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R

Reggaerover

Member
Posts
90
Location
Belgium
Hello everyone! I am new to the landy world. I recently bought a discovery 2 td5 from 2003. I bought it with the M and S lights flashing but after research i thought it could only be a bad xyz switch. I could have never been more wrong. I have tried many things but without luck. I have replaced the wiring loom to the gearbox. I have tried 2 xyz switches that I cleaned up and aligned correctly with the adjustment tool, I have placed a new battery that has 12.7V when car is of and (+/-)14.3V when running. First the lights would pop up after driving a couple meters but after changing all these things I can drive for a km or 2, it is never the same distance. I have also cleaned out the ecu for oil. I have sprayed the tranny ecu and plug with contact cleaner. Nothing seams to help. I am always getting the fault p0743. Also I recently bought a Bluetooth device that I plug in my sigaret lighter plug and when the fault is about to appear the music starts cracking realy bad and it’s stays like that even when I clear the code. Until I get into 3de gear again and then the music is normal again. I am absolutely out of ideas. Past weekend I have placed a new ground from the torque converter to the chassis and then I drove a whole day without problems but the day after the fault came back. Please can someone help me? ☹️
 
Is there a chance you have a problem with the wastegate and this is putting the idea of overfuellling into the ECU which is then putting it into limp mode?
You may have a sticky wastegate, so you need to look at that, ensure it is freed off and lubed as far as you can also
that the wastegate actuator rod has no fewer then 13 threads showing and the actuator is working properly.
Best of luck.
PS I haven't looked into the code.
but others on here will tell you what it is about.:):):)
 
Stanleysteamer said:
Is there a chance you have a problem with the wastegate and this is putting the idea of overfuellling into the ECU which is then putting it into limp mode?
You may have a sticky wastegate, so you need to look at that, ensure it is freed off and lubed as far as you can also
that the wastegate actuator rod has no fewer then 13 threads showing and the actuator is working properly.
Best of luck.
PS I haven't looked into the code.
but others on here will tell you what it is about.:):):)
Click to expand...
Stanleysteamer said:
Is there a chance you have a problem with the wastegate and this is putting the idea of overfuellling into the ECU which is then putting it into limp mode?
You may have a sticky wastegate, so you need to look at that, ensure it is freed off and lubed as far as you can also
that the wastegate actuator rod has no fewer then 13 threads showing and the actuator is working properly.
Best of luck.
PS I haven't looked into the code.
but others on here will tell you what it is about.:):):)
Click to expand...
Thanks for helping out! My knowledge of the disco is not so big can you maybe help me out where the wastegate is located on the car and how I know if it is sticky ? And how can I test if the actuator is working properly? I am learning every day from my car but still need a lot of help already big thanks for your help!
 
Take the engine cover off.
Standing in front of the car look to the right of the engine. Above the exhaust pipes off the manifold you will see the turbo protected by its metal cover. Sticking forward out of the cover is the wastegate actuating rod, a metal part threaded bar, which comes to an end in a metal cylinder mounted on the engine by two bolts and nuts, the actuator diaphragm. If the nuts are missing that will cause the limp home mode. It happened to me!
If the actuator is securely mounted, look down the bar to where the threads start, there should be 13 of these visible between where the threads start and the locking nut which secures the metal contraption and the knurled adjustment nut.
They say you can check if the waste gate on the turbo, (which is on the far end of the bar) is moving by grabbing hold of the bar with a pair of pliers of a mole grip and pushing and pulling on the bar. but I found it easier to undo the two 10mm nuts and free the actuator diaphragm from the mount. Once free you can actuate the bar yourself to see if the waste gate is stuck or not.
If you have to get to the turbo to free off the waste gate you need to take the heat shield off, which is a bit awkward, three nuts, or three bolts or a combination, I can't quite remember, but the one on the back is the trickiest. Once off, spray gunk on the end of the waste gate spindle until you free it off then keep moving it until you are sure it is completely free. I have no idea what you could lubricate it with as the turbo gets to a stupid temperature, I just stuck some ordinary oil on it and hoped for the best. it was OK.
The reassemble the way you took it apart.
Best of luck!
 
Stanleysteamer said:
Take the engine cover off.
Standing in front of the car look to the right of the engine. Above the exhaust pipes off the manifold you will see the turbo protected by its metal cover. Sticking forward out of the cover is the wastegate actuating rod, a metal part threaded bar, which comes to an end in a metal cylinder mounted on the engine by two bolts and nuts, the actuator diaphragm. If the nuts are missing that will cause the limp home mode. It happened to me!
If the actuator is securely mounted, look down the bar to where the threads start, there should be 13 of these visible between where the threads start and the locking nut which secures the metal contraption and the knurled adjustment nut.
They say you can check if the waste gate on the turbo, (which is on the far end of the bar) is moving by grabbing hold of the bar with a pair of pliers of a mole grip and pushing and pulling on the bar. but I found it easier to undo the two 10mm nuts and free the actuator diaphragm from the mount. Once free you can actuate the bar yourself to see if the waste gate is stuck or not.
If you have to get to the turbo to free off the waste gate you need to take the heat shield off, which is a bit awkward, three nuts, or three bolts or a combination, I can't quite remember, but the one on the back is the trickiest. Once off, spray gunk on the end of the waste gate spindle until you free it off then keep moving it until you are sure it is completely free. I have no idea what you could lubricate it with as the turbo gets to a stupid temperature, I just stuck some ordinary oil on it and hoped for the best. it was OK.
The reassemble the way you took it apart.
Best of luck!
Click to expand...
Thank you for the good explanation! I will definitely try this today, if not it will be for Saturday :) this is something complete different then all the things I have read on the whole internet! This gives me hope! Thanks a lot I will keep you updated :)
 
Before you go and do more than you need to what the symptoms are are these.
You jump in the car and turn it on, it runs fine and drives fine until you ask it for a bit more power, i.e. you try to accelerate, especially going up a hill.
Then the engine kind of feels strangled and you do not make normal progress at all. This is cos the wastegate is not being opened by the actuator. The turbo builds up too much pressure, the ECU senses this as overfuelling and cuts the fuel going into the engine to prevent damage. (This description may not be entirely accurate and others will jump on and make it clearer for you.) You are then forced to drive with it like this until you stop. Once you stop and turn the engine off, on restart, it is OK again until you ask the engine for a bit of power then it all happens all over again.
When it happened to me I had to endure this for 5 out of seven days of a holiday in Cornwall at Christmas as all the shops were shut and I couldn't buy two 6mm, (10mm spanner size) nuts and washers!
If this isn't exactly what is happening then you may have another fault, or faults.
 
Stanleysteamer said:
Before you go and do more than you need to what the symptoms are are these.
You jump in the car and turn it on, it runs fine and drives fine until you ask it for a bit more power, i.e. you try to accelerate, especially going up a hill.
Then the engine kind of feels strangled and you do not make normal progress at all. This is cos the wastegate is not being opened by the actuator. The turbo builds up too much pressure, the ECU senses this as overfuelling and cuts the fuel going into the engine to prevent damage. (This description may not be entirely accurate and others will jump on and make it clearer for you.) You are then forced to drive with it like this until you stop. Once you stop and turn the engine off, on restart, it is OK again until you ask the engine for a bit of power then it all happens all over again.
When it happened to me I had to endure this for 5 out of seven days of a holiday in Cornwall at Christmas as all the shops were shut and I couldn't buy two 6mm, (10mm spanner size) nuts and washers!
If this isn't exactly what is happening then you may have another fault, or faults.
Click to expand...
Yes most of the time the fault comes on after a hard acceleration like for example, going up a bridge and when down taking a roundabout that’s when it happens or when I drive 70km/h for 2km and then stop for a red light and then start to accelerate that’s also when it happens. But sometimes it just pops up when driven normal. I forgot to mension this but the fault code means P0743(7, 25)=* Torque converter lock- up solenoid (MV 3), open or short circuit. Can it still be the thing you said or ?
 
Reggaerover said:
Yeah was going to try this this weekend but I did change the wiring loom that hangs on top of the tranny box because that’s also a common cause of the m and s lights but the harnass was damaged but the threats weren’t but still replaced the loom with another one just to be sure.
Click to expand...
Unless you take the harness completely apart it is often well hidden.
Did you replace it with a new harness or a secondhand one? cos if the latter, it could still have the same fault.
 
Reggaerover said:
Yes most of the time the fault comes on after a hard acceleration like for example, going up a bridge and when down taking a roundabout that’s when it happens or when I drive 70km/h for 2km and then stop for a red light and then start to accelerate that’s also when it happens. But sometimes it just pops up when driven normal. I forgot to mension this but the fault code means P0743(7, 25)=* Torque converter lock- up solenoid (MV 3), open or short circuit. Can it still be the thing you said or ?
Click to expand...
The fault does sound very much like limp mode after a wastegate fault. whether it would put the fault code up because it is forced into limp mode by the engine ecu, i have no idea. i am not the electronics guru on here. Far from it!
Maybe @sierrafery will spot this and advise you.
Best of luck!
 
Stanleysteamer said:
Unless you take the harness completely apart it is often well hidden.
Did you replace it with a new harness or a secondhand one? cos if the latter, it could still have the same fault.
Click to expand...
I have a donor car, took the loom from that one so secondhand but that harnass was also A little damaged but took of a big peace of the harnass (not completely) and it all looked good, I also putted a ohm meter on every pin of the plugs and it all looked fine
 
Whereabouts in Belgium are you?
My ex-wife is half Belgian and came from the border village of Jeumont. I met her in Lille and spent many happy times in La Belgique!
 
Stanleysteamer said:
The fault does sound very much like limp mode after a wastegate fault. whether it would put the fault code up because it is forced into limp mode by the engine ecu, i have no idea. i am not the electronics guru on here. Far from it!
Maybe @sierrafery will spot this and advise you.
Best of luck!
Click to expand...
I really hope it is what you say haha I will check this weekend for the wastegate :) maybe sierrafery can help us more on the issue thanks a lot for the help I will keep you updated on the wastegate
 
Reggaerover said:
I have a donor car, took the loom from that one so secondhand but that harnass was also A little damaged but took of a big peace of the harnass (not completely) and it all looked good, I also putted a ohm meter on every pin of the plugs and it all looked fine
Click to expand...
If you checked every single wire was whole and the meter didn't move even when you moved the wire all over the place in every direction, and that all was insulated, then you may well be OK with it.
SF will come on about the code, but at the mo, my betting money is on the wastegate or the actuator or both.
 
Stanleysteamer said:
If you checked every single wire was whole and the meter didn't move even when you moved the wire all over the place in every direction, and that all was insulated, then you may well be OK with it.
SF will come on about the code, but at the mo, my betting money is on the wastegate or the actuator or both.
Click to expand...
Yeah I think the loom is good, maybe there is still something wrong with it but since i have to take apart my whole console for the loom I will wait for maybe other things to check first :)
 
Reggaerover said:
East-flanders close to Gent and Antwerp! :) the world is small! ;o
Click to expand...
Loved the castle in Gent, took some hilarious black and white photos when I was there with a mate, back in 78/79. Long before digital! Seem to remember it had a little museum in it which had a few torture chamber type items in it. Lots of fun. and pretty houses looking over the canal. Or was it a river?
Long long time ago now! Drove there in my Renault 6. Only see the odd one now in car shows. :):):)
 
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