Dectane light issues, advice welcome

[Jason Taylor]

My rear dectane lights have developed an intermittent fault. I first got a check rear left indicator message, when I did this I realised the plug was slightly damaged and was working it's way loose, I've taped up the plug which has resolved the issue, however I'm now getting a check taillight from the same unit, wiring, plugs etc are all good, I recreated the fault by unplugging it to get the fault displayed but when I reconnected it the fault wouldn't clear. It's a bit of a lottery at this point as to wether turning the ignition on/off will clear the fault, sometimes it does, other times it won't. I'm guessing the issue is with one of the controllers attached to the rear of the light unit, is there an option to have these units changed or will I require a new unit?

Tia

Jason

 

[CB911C4S]

I have had the same problem. It's intermittent and can go a decent time between faults displaying - although they are working OK. I took the car into the indy where I bought the car, and they had a good look at it but couldn't find a problem.

I picked up some errors on the Foxwell relating to the ampage draw being below minimum - I haven't checked any further but I wonder if that is a possible issue. I will go and check again and see what the error codes were and what they related to.

 

[Jason Taylor]

It's intermittent and can go a decent time between faults displaying - although they are working OK

I should have been clearer, the lights don't work when the message is displayed, although all the leds are ok and there's no visible signs of any issue.

 

[jl-c]

I think you will find that the 'controllers' as you call them are likely to be a resistance and a capacitor to fool the cars lamp check system. I suggest you fit a stock set of lights and try them. I suspect they will work fine. Then next , get an electronics person to strip (for strip read destroy as they kindly potted them all ) and check the units, you may well get a pleasent and cheap surprise. I hope so at least because I am an 'electronics person' and I also have Dectanes ! fingers crossed Yes, I am putting my money where my mouth is , may as well start 2022 with a bang :thumb:

 

[jl-c]

As an addendum to the above, get an 'electronics person' to connect a LCR meter across each removed black 'box' I hope the faulty ones will read differently to the ones that are still OK. If they don't know what a LCR meter is, they are not up to the job. :floor:

 

[Jason Taylor]

As an addendum to the above, get an 'electronics person' to connect a LCR meter across each removed black 'box' I hope the faulty ones will read differently to the ones that are still OK. If they don't know what a LCR meter is, they are not up to the job. :floor:

Perfect I'll do that, cheers

 

[DucatiRob]

I would guess that the internal load resistors have broken down over time, easy solution would be to fit some cheap ballast resistors in parallel.

https://www.ebay.co.uk/itm/123335574597

 

[jl-c]

I would guess that the internal load resistors have broken down over time, easy solution would be to fit some cheap ballast resistors in parallel.

https://www.ebay.co.uk/itm/123335574597

Agreed but I think they are probably a little more complicated than that and are likely a CR network to fool the bulb check. On a 997 it is particularly fussy as those who have tried to fit LED bulbs have discovered. I am yet to strip down the black boxes on the rear of a dectane and find out. Anyone got a failed one and I will happily attempt to get it apart so the contents are still able to be identified :dont know:

 

[DucatiRob]

I would guess that the internal load resistors have broken down over time, easy solution would be to fit some cheap ballast resistors in parallel.

https://www.ebay.co.uk/itm/123335574597

Agreed but I think they are probably a little more complicated than that and are likely a CR network to fool the bulb check. On a 997 it is particularly fussy as those who have tried to fit LED bulbs have discovered. I am yet to strip down the black boxes on the rear of a dectane and find out. Anyone got a failed one and I will happily attempt to get it apart so the contents are still able to be identified :dont know:

You could well be right, I know that the Gen 2 rear lights have a bunch of electronics buried in them but I don't think the Detanes are quite as complicated. I had a similar issue with my front DRL units, working perfectly but throwing intermittent errors. Solved with fitting the eBay load resistors.