Blowing bulbs and ECUs. Renault Megane

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Sat 26 Feb 2005 17:21
Blowing bulbs and ECUs. Renault Megane - BobG
My 2003 megane has a habit of blowing side light bulbs about every 3 months. I only use toop branded makes ( usually Osram )which I buy from a reputable local independent business. On my last visit a local auto electrician told me that in his opinion this is due to spikes created by thew ECU. The local dealer confirmed that over the past couple of years his sales of bulbs had more than doubled. The car was checked at the last service and ( at the time ) no fault coud be found. Any thoughts ?

Bob G.
Reply | Report as offensive | Link
Sat 26 Feb 2005 17:27
Blowing bulbs and ECUs - Pugugly {P}
This is definately an issue with Ford Focii. Needs a software and or a hardware fix.
Reply | Report as offensive | Link
Sat 26 Feb 2005 17:36
Blowing bulbs and ECUs - Altea Ego
ECU's cant generate spikes. Its a 5 volt device. External controllers (that is the electronic switches) might be able to
Reply | Report as offensive | Link
Sat 26 Feb 2005 17:44
Blowing bulbs and ECUs - Schnitzel
"On my last visit a local auto electrician told me that in his opinion this is due to spikes created by thew ECU"

He is REALLY an "Auto Electrician"???? or a purveyor of "folklore and automotive-mysticism" like most of the vehicle repair trade? Sounds like the latter, I have had bad experiences with these buffoons, but since I joined here and other motoring forums, I can see it's widespread. Bulbs are very tolerant of spikes anyway, probably the most tolerant electrical items on the car, I would suspect vibration from modern large yet lightweight thin plastic lamps.
Reply | Report as offensive | Link
Sat 26 Feb 2005 17:56
Blowing bulbs and ECUs - Pugugly {P}
A contact within the Ford Empire told me last week that spiking was most certainly an issue in the bulb blowing business. He has since e-mailed me the full story, unfortunately it is on my work system. I'll dig out on Monday.
Reply | Report as offensive | Link
Sat 26 Feb 2005 18:20
Blowing bulbs and ECUs - Aprilia
It is caused by 'load dumping'. Most likely suspect IMHO would be the alternator, then other inductive loads like EPAS etc.
Reply | Report as offensive | Link
Sat 26 Feb 2005 19:00
Blowing bulbs and ECUs - Schnitzel
A contact within the Ford Empire told me last week that spiking was most certainly an issue in the bulb blowing business. He has since e-mailed me the full story, unfortunately it is on my work system. I'll dig out on Monday.

Well no wonder they can neither design it properly in the first place, nor cure the problem, if that's what they want to believe.
Reply | Report as offensive | Link
Sat 26 Feb 2005 19:30
Blowing bulbs and ECUs - BobG
Thanks for the advice. As somebody with a background in science I could not make sense of the original statement about so called spikes.
Reply | Report as offensive | Link
Sat 26 Feb 2005 19:52
Blowing bulbs and ECUs - Civic8
Spike..Sudden voltage overload for a fraction of a second.Bulbs dont like them..Other components may have protection against this..IMHO I think its Alternator.But may be wrong??
--
Steve
Reply | Report as offensive | Link
Sat 26 Feb 2005 20:38
Blowing bulbs and ECUs - Andrew Moorey (Tune-Up)
What you have to bear in mind is that the boffins have decided to regulate the output of the alternator with the ECU on a lot of newer cars. Most manufacturers still haven't got the ECU controlling the basics reliably yet so is it any wonder that the charging system sometimes runs awry? ;>>
Andrew
--
Simplicate and add lightness!!
Reply | Report as offensive | Link
Sat 26 Feb 2005 20:41
Blowing bulbs and ECUs - mfarrow
Any chance it could be the voltage regulators in the ECU giving out spikes?
Reply | Report as offensive | Link
Sat 26 Feb 2005 20:47
Blowing bulbs and ECUs - Kevin
I've had three headlight bulbs blow on my Jag in the last 18 months. Luckily they are not too difficult to replace and the cuts and scratches on my hand heal in a few days anyway.

If it happened more frequently or they were more difficult to replace I'd be looking at installing filters in the feed wires.

>Bulbs are very tolerant of spikes anyway,

They are very tolerant, but less so when cold. Very early in my career I designed process control systems for mining and manufacturing industry. Normal practice was to include bypass resistors in lamp switching circuits to keep a small current flowing through the lamps even when switched off. It reduces thermal shock.

On a large mining plant with thousands of indicator lamps, often in the middle of nowhere and with a lousy mains supply, replacing blown bulbs was a significant safety and maintenance problem.

Kevin...
Reply | Report as offensive | Link
Sat 26 Feb 2005 21:52
Blowing bulbs and ECUs - David Horn
Similar practice in theatre lighting - any connected lamp is permanently on "pre-heat", which keeps it hot but not emitting light. They then reach full brightness a lot more quickly and a more tolerant of a rapid voltage increase.
Reply | Report as offensive | Link
Sat 26 Feb 2005 23:41
Blowing bulbs and ECUs - Aprilia
One thing to bear in mind is that the alternator voltage regulator needs to see the battery load to keep it working properly. If you have a dodgy battery connection then the alternator output can intermittantly spike up - so check your battery connections (inc. earth straps etc.).
Reply | Report as offensive | Link
Sun 27 Feb 2005 15:56
Blowing bulbs and ECUs - BobG
I'll check all the connections and clean up any earth connections before I put in new bulbs
Reply | Report as offensive | Link

10 warranty myths exposed

Here’s how to sort the fact from the fiction when it comes to car warranties.

Cheap Car Warranties

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide