M and S lights, limp mode, p0743

Hi, as long as P0743 keeps coming on and you are certain that the harness is OK you have to rule out the MV3 solenoid and you can do that only by changing it with new or verified working one. I've seen cases when this solenoid vas sticking and after it was tested with power inputs it got unstuck but t's possible that your's has an intermittent short circuit and when it occurs the voltage drop affects the music too cos the EAT ECU shares the same earth with the amplifier, check connections in earth header C0708 maybe you are lucky to be a bad contact there ... do you have access to nanocom or hawkeye ?

sierrafery said:

Hi, as long as P0743 keeps coming on and you are certain that the harness is OK you have to rule out the MV3 solenoid and you can do that only by changing it with new or verified working one. I've seen cases when this solenoid vas sticking and after it was tested with power inputs it got unstuck but t's possible that your's has an intermittent short circuit and when it occurs the voltage drop affects the music too cos the EAT ECU shares the same earth with the amplifier, check connections in earth header C0708 maybe you are lucky to be a bad contact there ... do you have access to nanocom or hawkeye ?

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Oh okey and is it possible to replace the MV3 solenoid myself or is it a hard job ? I am not the best car mechanic but I can try. Oh okey that explains the bad music quality! I will check the earth header C0708 maybe it is a bad contact because when we bought it it only gave the code for a bad xyz switch and after taking apart the midconsole this fault came. Yes I have a nanocom.

After you checked the earth header disconnect C0677, insert +12V with a wire into pin 3 and earth to pin 6 then you should hear te solenoid clicking, do it more times eventually compare the sound with MV2 which will click when you give earth to pin 4

sierrafery said:

After you checked the earth header disconnect C0677, insert +12V with a wire into pin 3 and earth to pin 6 then you should hear te solenoid clicking, do it more times eventually compare the sound with MV2 which will click when you give earth to pin 4

Click to expand...

Okey thank you sierrafery I will first check earth C0708 and after I will put a 12V on those pins but I don’t have a 12V module here at home so that will be for this weekend, a friend of mine has one.

sierrafery said:

After you checked the earth header disconnect C0677, insert +12V with a wire into pin 3 and earth to pin 6 then you should hear te solenoid clicking, do it more times eventually compare the sound with MV2 which will click when you give earth to pin 4

Click to expand...

Should my battery be disconnected to do al this ?

sierrafery said:

After you checked the earth header disconnect C0677, insert +12V with a wire into pin 3 and earth to pin 6 then you should hear te solenoid clicking, do it more times eventually compare the sound with MV2 which will click when you give earth to pin 4

Click to expand...

So my center console is apart, I looked at every plug for dirt or bad contact. I cleaned every plug with contact cleaner and plugged them back in properly. Now after the research of my brother we are still here with some questions. Is the plug C0708 also connected with the seat heater ? Because the driver side the seat heater doesn’t work. We weren’t able to do a ohm test because my ohm meter isn’t working good. This weekend I will test for better results. Also had plug C0243 also have something to do with the solenoids if so, test this to or is this one irrelevant ? Thanks a lot in advance!

sierrafery said:

Hi, as long as P0743 keeps coming on and you are certain that the harness is OK you have to rule out the MV3 solenoid and you can do that only by changing it with new or verified working one. I've seen cases when this solenoid vas sticking and after it was tested with power inputs it got unstuck but t's possible that your's has an intermittent short circuit and when it occurs the voltage drop affects the music too cos the EAT ECU shares the same earth with the amplifier, check connections in earth header C0708 maybe you are lucky to be a bad contact there ... do you have access to nanocom or hawkeye ?

Click to expand...

Excuse me for asking but where is this solenoid?

The solenoids are connected only to C0677, you dont have to disconnect the battery nor you need any 12V module, take a live from the fusebox, hook a wire to the brown wire on the brown plug which is on the front of the fusebox or where ever you have a live there and earth from body

the earth for seat heaters is also in C0708

Stanleysteamer said:

Excuse me for asking but where is this solenoid

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in the gearbox's valve block, nr 3 http://new.lrcat.com/#!/1232/38569/38741/2983/38814

sierrafery said:

The solenoids are connected only to C0677, you dont have to disconnect the battery nor you need any 12V module, take a live from the fusebox, hook a wire to the brown wire on the brown plug which is on the front of the fusebox or where ever you have a live there and earth from body

the earth for seat heaters is also in C0708

in the gearbox's valve block, nr 3 http://new.lrcat.com/#!/1232/38569/38741/2983/38814

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This is what I was worried about. So if its fecked then will the gear box have to be taken off and apart? Or can he just excite the solenoid a few times to help clear the contacts?
I have no idea with modern electronic gearboxes. Old fashioned slush boxes could be reworked without too much difficulty. And peeps did it to make their boxes change differently. But modern ones?

AFAIK the valve block can be removed with gearbox in situ

sierrafery said:

AFAIK the valve block can be removed with gearbox in situ

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Right!
Game on then!
good news!

sierrafery said:

The solenoids are connected only to C0677, you dont have to disconnect the battery nor you need any 12V module, take a live from the fusebox, hook a wire to the brown wire on the brown plug which is on the front of the fusebox or where ever you have a live there and earth from body

the earth for seat heaters is also in C0708

in the gearbox's valve block, nr 3 http://new.lrcat.com/#!/1232/38569/38741/2983/38814

Click to expand...

Okey thanks today I will give the solenoid a push in the back with the 12V and hope for the best I will keep you guys updated! Already big thanks for al the help!

so after the test on C0677 with the 12V we concluded a short in the circuit.

1) only tapping 12v on pin 3 (no earth on 4 or 6), solenoid clicked
2) 12v on pin 3 and earth on pin 4, solenoid clicked every time we tapped the earth on 4
3) 12v on pin 3 and earth on pin 6, solenoid DIDN'T click when we tapped the earth on 6
we tought the loom might have a short somewhere so we changed the loom again with a tested good one. step 1-3 was the same result. so what is the next step?

@sierrafery

My conclusion is that MV3 is faulty or there's a short to earth in the valve block as it should behave the same when you give earth to pin 6(MV3) like to pin 4(MV2) , pin 3 is common live for all the solenoids and they are all activated on the earth path as it's PWM so try with earth to pin 1(MV1) and to pin 2(MV4) too and if all except pin 6(MV3) are the same then the valve block has to come out and checked, eventually the solenoid replaced

sierrafery said:

My conclusion is that MV3 is faulty or there's a short to earth in the valve block as it should behave the same when you give earth to pin 6(MV3) like to pin 4(MV2) , pin 3 is common live for all the solenoids and they are all activated on the earth path as it's PWM so try with earth to pin 1(MV1) and to pin 2(MV4) too and if all except pin 6(MV3) are the same then the valve block has to come out and checked, eventually the solenoid replaced

Click to expand...

Okey thanks we ordered the solenoid and hopefully we can replace him soon! Thanks for all the help! Do you have a recommendation from video or manual how to do this job properly ? Because I have no idea how to get to the solenoid.

Download this https://www.sugarsync.com/pf/D8700125_05791262_69940?directDownload=true (it's valid for '03 too) then go to the autobox - repairs and there you find instructions for valve block and solenoids

sierrafery said:

Download this https://www.sugarsync.com/pf/D8700125_05791262_69940?directDownload=true (it's valid for '03 too) then go to the autobox - repairs and there you find instructions for valve block and solenoids

Click to expand...

Okey thanks for all the help!

sierrafery said:

Download this https://www.sugarsync.com/pf/D8700125_05791262_69940?directDownload=true (it's valid for '03 too) then go to the autobox - repairs and there you find instructions for valve block and solenoids

Click to expand...

@sierrafery we found a guy from The Netherlands who selled us a good working complete valve with all the solenoids on. Today we changed the complete valve instead of just the solenoid. We fitted everything back together like the manual said. We changed the tranny oil back to new oil. After wanting to drive in reverse the car did not do anything, didn’t move even after giving a lot of gas. In park the car started realy slow forward. Neutral also started driving like it was in first gear, drive seemed good but 3th and second manual gear also felt like it was in first. We couldn’t even put the poke in 1th gear. Can you please help us because we are kinda freaking out. We went for a test drive we thought maybe the oil needed to circulate more. But after driving in D (drive) if I let go the gas pedal the car braked as if it braked on the engine. It was a weird sound as if the clutch didn’t open or something. I can give you a good pick of the valve that I replaced and the one I replaced it with.

Reggaerover said:

@sierrafery we found a guy from The Netherlands who selled us a good working complete valve with all the solenoids on. Today we changed the complete valve instead of just the solenoid. We fitted everything back together like the manual said. We changed the tranny oil back to new oil. After wanting to drive in reverse the car did not do anything, didn’t move even after giving a lot of gas. In park the car started realy slow forward. Neutral also started driving like it was in first gear, drive seemed good but 3th and second manual gear also felt like it was in first. We couldn’t even put the poke in 1th gear. Can you please help us because we are kinda freaking out. We went for a test drive we thought maybe the oil needed to circulate more. But after driving in D (drive) if I let go the gas pedal the car braked as if it braked on the engine. It was a weird sound as if the clutch didn’t open or something. I can give you a good pick of the valve that I replaced and the one I replaced it with.

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Also I forgot to say but the lever stand and the dashboard were the same. So lever in D was D on dash, N on lever was N on dash,....

Did you change the oil and filter with the procedure shown in the manual? that's important... if yes then IMO better replace that solenoid cos that valve block seems fubar, though go into the autobox ECU with nanocom and give it a "reset adaptive values" maybe it helps but i'm not confident with this... are you sure that the valve block was removed from a D2 cos there are same autoboxes on RR P38 too which are not working the same ?