BCU failure or full of water

andrei_teo · 24th August 2016, 09:19

Hi guys,

It s really annoying what s happening to me right now, i ll try to explain with all details. Starting some weeks ago, after it s raining my car goes crazy. What i noticed first, the wipers start work even if i m out of the car and the car is locked. The wipers stop just when i turn the 2nd position of the key. First i thought it s the rain sensor failure but past days i noticed even the interior lights turning on and off many times alone, the drivers windows switch not working anymore, but the windows are working if you use the other switches. Now i have to disconnect the battery all the time and after i reconnect it and turn the ignition on, one of the windows randomly goes down. Moreover i cant lock the car anymore through buttons of the key, the car do the horn noise as a door is opened. And if i can succed closing it like that, in some minutes the alarm will start alone and will not stop even if i turn the ignition on. It happened two times for me until now and everytime after some days after the rain, if it s hot outside the car work as before, without any problem. All the time i checked the ECU that is placed under the windscreen and notime it wasnt water there. Did anyone faced with such a problem ? Thank you a lot for your answers.

Sincerly,
Andrei.

Greeners · 24th August 2016, 09:38

It sounds like the ECU has been wet at sometime. If the BCU has got wet then the ECU has.

You need to take the ECU out and look for tide marks on it, then contact one of the T4 guys for a test and or repair

andrei_teo · 24th August 2016, 09:51

I contacted a guy with T4 and no error. That s why he couldnt tell me from where is the problem. He asked me to check the ecu if there is water there but i told him the same, i didnt find water there. Even when it was raining i checked and no water there. What i can say is that i dont have anymore the silicone pipe on the bottom there, so the water drains so fast. Can it be this a problem ?

Greeners · 24th August 2016, 09:53

you need to physically remove the ecu and check it.

Plezier · 24th August 2016, 10:23

Have you checked that the plenum drains are clear?

On the ECU in my recently acquired CDT there was no easily visible tide mark but removing the back plate to the ECU revealed rusted screws and some wite water marking inside. After repair by Marinabrian it is all well.

andrei_teo · 24th August 2016, 12:28

Inside ECU compartment i know that there is a plenum drain, there it cant be clogged, i dont have anymore the rubber sleeve, so the water drains directly outside. Thats why i think that the water can not be there. I will take out these days the ECU and i ll post some photos here. Any other ideas from where the water can go in ? Or other computer that can cause these symptomes ?

Plezier · 24th August 2016, 17:44

With no rubber tube then surely the water is runing inside the cabin under the carpets?

andrei_teo · 25th August 2016, 10:11

I checked under carpets from the passenger s place and i didnt find anything. I checked the next day after the rain. I checked also the carpet that s under the fuse panel and still no water.

Plezier · 25th August 2016, 14:12

It was just a thought as someone had pulled one through on my Connie and under the carpets was soaked.

Dallas · 25th August 2016, 16:17

Does your car have a sunroof, could the drain tubes be the issue?

It has been known for the EWS unit to get wet and corrode, this normally effects the immobiliser and central locking etc.

24th August 2016, 09:19	#1
andrei_teo Newbie Rover 75 Saloon Join Date: Mar 2016 Location: Bucharest Posts: 7 Thanks: 0 Thanked 1 Time in 1 Post	BCU failure or full of water Hi guys, It s really annoying what s happening to me right now, i ll try to explain with all details. Starting some weeks ago, after it s raining my car goes crazy. What i noticed first, the wipers start work even if i m out of the car and the car is locked. The wipers stop just when i turn the 2nd position of the key. First i thought it s the rain sensor failure but past days i noticed even the interior lights turning on and off many times alone, the drivers windows switch not working anymore, but the windows are working if you use the other switches. Now i have to disconnect the battery all the time and after i reconnect it and turn the ignition on, one of the windows randomly goes down. Moreover i cant lock the car anymore through buttons of the key, the car do the horn noise as a door is opened. And if i can succed closing it like that, in some minutes the alarm will start alone and will not stop even if i turn the ignition on. It happened two times for me until now and everytime after some days after the rain, if it s hot outside the car work as before, without any problem. All the time i checked the ECU that is placed under the windscreen and notime it wasnt water there. Did anyone faced with such a problem ? Thank you a lot for your answers. Sincerly, Andrei.

24th August 2016, 09:38	#2
Greeners Moderator MG-ZTT Join Date: Mar 2007 Location: Ware, Herts Posts: 19,798 Thanks: 161 Thanked 1,249 Times in 1,036 Posts	It sounds like the ECU has been wet at sometime. If the BCU has got wet then the ECU has. You need to take the ECU out and look for tide marks on it, then contact one of the T4 guys for a test and or repair __________________ *David* Impecunity is the mother of ingenuity Useful how to's for common problems Car Of The Month Jan 2014 [SatNav Power Down] [Coolant Level] [SatNav Repair] [Diesel Non Starting] [Paint Codes] [Rear Light Seals] [Reversing Light Switch] [Bleeding Brakes][Sunroof Drain] [Early ZT's][Instrument Pack Diagnostics][ATC Diagnostics]

24th August 2016, 09:53	#4
Greeners Moderator MG-ZTT Join Date: Mar 2007 Location: Ware, Herts Posts: 19,798 Thanks: 161 Thanked 1,249 Times in 1,036 Posts	you need to physically remove the ecu and check it. __________________ *David* Impecunity is the mother of ingenuity Useful how to's for common problems Car Of The Month Jan 2014 [SatNav Power Down] [Coolant Level] [SatNav Repair] [Diesel Non Starting] [Paint Codes] [Rear Light Seals] [Reversing Light Switch] [Bleeding Brakes][Sunroof Drain] [Early ZT's][Instrument Pack Diagnostics][ATC Diagnostics]

24th August 2016, 10:23	#5
Plezier I really should get out more....... Mercedes C Class CDI estate (2003) Join Date: Sep 2012 Location: Gradina Posts: 2,652 Thanks: 62 Thanked 137 Times in 119 Posts	Have you checked that the plenum drains are clear? On the ECU in my recently acquired CDT there was no easily visible tide mark but removing the back plate to the ECU revealed rusted screws and some wite water marking inside. After repair by Marinabrian it is all well. __________________ Classic SE CDT sadly lost in a severe collision.

24th August 2016, 17:44	#7
Plezier I really should get out more....... Mercedes C Class CDI estate (2003) Join Date: Sep 2012 Location: Gradina Posts: 2,652 Thanks: 62 Thanked 137 Times in 119 Posts	With no rubber tube then surely the water is runing inside the cabin under the carpets? __________________ Classic SE CDT sadly lost in a severe collision.

24th August 2016, 09:51	#3
andrei_teo Newbie Rover 75 Saloon Join Date: Mar 2016 Location: Bucharest Posts: 7 Thanks: 0 Thanked 1 Time in 1 Post	I contacted a guy with T4 and no error. That s why he couldnt tell me from where is the problem. He asked me to check the ecu if there is water there but i told him the same, i didnt find water there. Even when it was raining i checked and no water there. What i can say is that i dont have anymore the silicone pipe on the bottom there, so the water drains so fast. Can it be this a problem ?

24th August 2016, 12:28	#6
andrei_teo Newbie Rover 75 Saloon Join Date: Mar 2016 Location: Bucharest Posts: 7 Thanks: 0 Thanked 1 Time in 1 Post	Inside ECU compartment i know that there is a plenum drain, there it cant be clogged, i dont have anymore the rubber sleeve, so the water drains directly outside. Thats why i think that the water can not be there. I will take out these days the ECU and i ll post some photos here. Any other ideas from where the water can go in ? Or other computer that can cause these symptomes ?

25th August 2016, 10:11	#8
andrei_teo Newbie Rover 75 Saloon Join Date: Mar 2016 Location: Bucharest Posts: 7 Thanks: 0 Thanked 1 Time in 1 Post	I checked under carpets from the passenger s place and i didnt find anything. I checked the next day after the rain. I checked also the carpet that s under the fuse panel and still no water.

25th August 2016, 14:12	#9
Plezier I really should get out more....... Mercedes C Class CDI estate (2003) Join Date: Sep 2012 Location: Gradina Posts: 2,652 Thanks: 62 Thanked 137 Times in 119 Posts	It was just a thought as someone had pulled one through on my Connie and under the carpets was soaked. __________________ Classic SE CDT sadly lost in a severe collision.

25th August 2016, 16:17	#10
Dallas This is my second home 1979 Capri 1.6L, 1982 Capri 1.6L, 2016 Dacia Stepway Join Date: Jun 2009 Location: Dorset Posts: 8,595 Thanks: 3,496 Thanked 3,397 Times in 2,218 Posts	Does your car have a sunroof, could the drain tubes be the issue? It has been known for the EWS unit to get wet and corrode, this normally effects the immobiliser and central locking etc.

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