E89 roof relay change
- Thread starter Smartbear
- Start date
No kidding - If you told me that was a pic of a relay that had failed - I would not doubt you for a momentscootr said:Jeez, you need to go out & buy a lottery ticket straight away
Rob
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That’s not nice, however it would have become a whole lot worse if those contacts had welded themselves together and become “stuck up”
Have you seen the Australian bush fires?
Rob
What is needed i some suppression on the contacts, like some capacitors to reduce the arcing.
https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=13C3236_AppNote&DocType=CS&DocLang=EN
Would seem no easy solution to contact arcing, so just treat the relay as a consumable.
Also i rarely operate roof on battery power alone, but mostly always when the engine is running. The highr volts from the alternator should allow the motor to pull fewer amps.
If BMW manual says operate roof with engine running.
These smart modules with remote roof operation may not be a good thing.
Perhaps that is why my cars relays have lasted 10 years before any problems.
https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=13C3236_AppNote&DocType=CS&DocLang=EN
Would seem no easy solution to contact arcing, so just treat the relay as a consumable.
Also i rarely operate roof on battery power alone, but mostly always when the engine is running. The highr volts from the alternator should allow the motor to pull fewer amps.
If BMW manual says operate roof with engine running.
These smart modules with remote roof operation may not be a good thing.
Perhaps that is why my cars relays have lasted 10 years before any problems.
scootr said:I'm going for a record here :lol: A your guy's suggestion I just changed the relays out on my 2010 Z and here is a pic below of the one I removed. The question is how much longer could relay have continued to work? Once? Twice?Yikes.
I feel like I dodged a bullet on this one, thank you
What were the date stamps on the relays? were they the original ones on the car from new?
This is a design fault and BMW should rectify it by a recall. Yeah, laugh away.... 
The "burning" of the electrical contact is caused by the making and breaking over many cycles of an inductive circuit (the motor). This could be fixed by some £1 capacitors across the relay to absorb the spike from the inductive make/break of contact.
The "burning" of the electrical contact is caused by the making and breaking over many cycles of an inductive circuit (the motor). This could be fixed by some £1 capacitors across the relay to absorb the spike from the inductive make/break of contact.
Sorry I just seen this! Yeah, i agree 100%.flybobbie said:
Sorry to go on.... People say there is an intrinsic fault with the relays. I doubt that very much. A relay can operate millions of times and I doubt folks operate the roof that often. If these relays are burning out it is the surrounding circuity - or lack of - that is causing the contacts to burn. Swapping the relays is addressing the problem, not the cause.
Thats said, since I am not inclined to redesign the roof, I'll change the relays too!
Thats said, since I am not inclined to redesign the roof, I'll change the relays too!
scootr said:
Same like mine, the relays were original from 2009 good job we changed them! By the way as Robbie posted earlier there is no need to undo any screws, you just press the black tab above the two red wires and the relay assembly pushes out and then you can tilt them upwards to remove them and replace them. Took me literally 5 mins without any tools.
£16.12 each including VAT from BMW, they have to be ordered in and lead time is two days. Think I will do this job, I am all into simple preventative maintenance.
flybobbie said:
It is actually the opposite! The pitting of the contacts is caused when the contacts open and the voltage tries to maintain the flow of electricity across them - the higher the voltage, the higher the current that will flow to maintain the electricity flow across them and hence the bigger arc and pitting.
So it is better on the relays to operate the roof with the engine off
keving1 said:flybobbie said:
It is actually the opposite! The pitting of the contacts is caused when the contacts open and the voltage tries to maintain the flow of electricity across them - the higher the voltage, the higher the current that will flow to maintain the electricity flow across them and hence the bigger arc and pitting.
So it is better on the relays to operate the roof with the engine off
I'm not convinced that's right. The roof motor will draw fewer amps when the voltage is higher. Amperage is what causes the pitting when the contacts make and break. Ideally these relays would have magnetic breakout but alas, I plan on replacing every 2-3 years now that I know what's up.
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Anonymous
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It may or may not be advantageous to the relay to have 12v across it rather than 14v..technically I think its de minimus...BUT..
Its for sure a major unecessary strain on the battery, especially after a long period of inactivity, and can result if the battery is low getting stuck half way etc..so..IMHO..much much much better to run the engine then operate the roof!!
Its for sure a major unecessary strain on the battery, especially after a long period of inactivity, and can result if the battery is low getting stuck half way etc..so..IMHO..much much much better to run the engine then operate the roof!!
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Anonymous
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Great article!