R/O/S light cluster stuck on. Help needed.

Bjm1982 · 1 Apr 2016

My 2006 987 Cayman's R/O/S light cluster is stuck on. All the lights are illuminated and I don't know why. This being whether the car is on or off.

Last night when I locked the car I got the single beep which I don't usually get, but at that time nothing appeared open (door/bonnet etc). The rear light wasn't on at this time.

I'm also getting the 'Failire Spoiler Control' but this seems to be working fine?

My brake light bulb had died on this cluster a few days ago and I literally had the new bulb delivered today. So I put this in hoping this may have been the cause to the problem. But still all the lights are stuck on.

Has anyone got any idea what the issue may be? I would take it to my Porshce garage but they are closed weekends.

deMort · 1 Apr 2016

hmmm can you check under the passenger seat to see if its wet there .. its possible water has got onto the rear cu and that would cause this sort of thing.

Bjm1982 · 1 Apr 2016

Demort said:
hmmm can you check under the passenger seat to see if its wet there .. its possible water has got onto the rear cu and that would cause this sort of thing.

I just had a look and found my water bottle under the seat. Although I cannot see any water there I know this bottle had a slight leak on it.

If a tiny bit of water has got into it would you know how to remedy this?

Thank you so much for your answer. You know your stuff.

deMort · 2 Apr 2016

Your not going to like my answer im afraid , its a new rear control unit , it only takes a small amount of water to get inside the unit to damage it as its permanently live so will short out.

If your ok with Diy , remove the passenger seat , disconnect the battery then remove the Black box with x3 wireing connections on it ( rear cu ) the case will unclip and you can then see the circuit board and what damage there is , depending on what you find will say if it can be cleaned up or not.

If you find a large green area of corrosion DO NOT TOUCH IT , just reassemble and refit it , its also part of the alarm system and if badly damaged will stop the car from starting, trying to clean it could make it worse in that case .

If its got to be replaced an Indy can also do it but it will need codeing so not a total Diy job im afraid as a tester will be needed.

The only plus side is that if its corroded you will have saved your self diagnosis time from the garage trying to find the fault.

Its a stupid place to fit a control unit (lowest point on the car) but at least a Cayman doesnt suffer from water leaks .. imagine it in a Boxster .. common fault on those due to rear drains blocking.

Bjm1982 · 2 Apr 2016

Demort said:
Your not going to like my answer im afraid , its a new rear control unit , it only takes a small amount of water to get inside the unit to damage it as its permanently live so will short out.

If your ok with Diy , remove the passenger seat , disconnect the battery then remove the Black box with x3 wireing connections on it ( rear cu ) the case will unclip and you can then see the circuit board and what damage there is , depending on what you find will say if it can be cleaned up or not.

If you find a large green area of corrosion DO NOT TOUCH IT , just reassemble and refit it , its also part of the alarm system and if badly damaged will stop the car from starting, trying to clean it could make it worse in that case .

If its got to be replaced an Indy can also do it but it will need codeing so not a total Diy job im afraid as a tester will be needed.

The only plus side is that if its corroded you will have saved your self diagnosis time from the garage trying to find the fault.

Its a stupid place to fit a control unit (lowest point on the car) but at least a Cayman doesnt suffer from water leaks .. imagine it in a Boxster .. common fault on those due to rear drains blocking.

Thanks for the detailed information. I did as you said and took out the rear control unit. It was dripping out water, but wasn't too bad. When I opened it up to see the circuit board there was some green/white gloopy wetness where I think corrosion had started, but luckily as I spotted this early and disconnected the battery I don't think it fried it too much.

I used compressed air and isopropyl alcohol to clean it with a soft brush and it cleaned up and dried well.

Upon re-installing the unit the light cluster went back to normal and all the error codes on the dash went away (other than the psm which reset itself after a short drive)

i don't think I am completely free of the issue yet though as when I lock the car now I get a double flash of the hazards and a single beep sound. The car didn't do this before. Do you know whether this is likely to be a problem? I read somewhere that the car can be set to beep when locking, but then other articles I have read states that it normally indicates that something is open on the car (which I have checked and all appears closed and secure)

If I do end up having to get a new rear control unit, are they time consuming or expensive for the dealer to recode? I called Porsche today, but there is no one until Monday than can quote me on the coding.

Thanks for all your help. i have only had the car a couple of months so it would have taken me ages to figure this out on my own.

deMort · 2 Apr 2016

Psm was because the battery was disconnected .. not the rear cu , a drive over 6mph will reset that.

A check of the codeing will see if its changed .. but i think its unlikely .. a damaged cu will cause strange problems and i dont think altering the codeing will help here.

Its not a huge job to replace and code , you have already removed it so you have an idear how much time to fit a new one .. codeing will take 10 mins or so .. plug a tester on , select rear cu .. code 6 different options i think .. might be 7

.. you press a button basically !

Im unsure of the cost of the cu though , i fit them but dont price them , but as i mentioned it can be done at an indy or an OPC .. indy will be cheaper.

Its hard to say if the new faults will be a problem as they weren,t there before and as that control unit controls that function it is that rear cu thats causeing it .. it is damaged in other words , try it for a few days and see if you have any battery problems .. if not and your happy with it then leave it and see how it goes.

Btw .. welcome to porsche or to the cayman if your new .. feel free to PM me or post on forums any questions.

And your welcome , to solve a problem is why i come here

R/O/S light cluster stuck on. Help needed.

Bjm1982

New member

deMort

Monaco

Bjm1982

New member

deMort

Monaco

Bjm1982

New member

deMort

Monaco

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