Megane Coupe electrical trouble

[JamesQB]

Hi all,

Megane Coupe 1.6 16V petrol, year 2000.

Weird occurrence tonight that's stopped me using car for time being.

Driving along at 40 tonight when the dipped beam bulbs on the car both blew at the same instant, and the battery light, STOP light, SERV light, ABS light and airbag light came on.

Pulled over and checked bulbs. Both melted. Only got them few days ago - Philips Extreme Power ones (55W like normal), cost a pretty penny.

Radio was switching itself on and off as I pulled forward on to the grass verge, airbag light went out and ABS started going out then flickering on when pulling forward.

Waiting to be collected since didn't want to risk re-occurrence on the 60mph road to home with few verges in pitch black, I started the car and drove to nearby car park. When I pulled up, I noticed all the lights above had gone off on the dashboard!

Must be a surge to kill both headlights at same time, so is my noisy alternator the trouble (found out it's noisy when sourcing loud whine from engine - seems to be the idler pulley bearing, new kit on way. Alternator sounded rough when spinning by hand during search for cause of whining)? Why did so many dashboard lights come on?

Not sure what to make of it or what I need to do to ensure it doesn't happen again!

[antz]

Hi all,

Megane Coupe 1.6 16V petrol, year 2000.

Weird occurrence tonight that's stopped me using car for time being.

Driving along at 40 tonight when the dipped beam bulbs on the car both blew at the same instant, and the battery light, STOP light, SERV light, ABS light and airbag light came on.

Pulled over and checked bulbs. Both melted. Only got them few days ago - Philips Extreme Power ones (55W like normal), cost a pretty penny.

Radio was switching itself on and off as I pulled forward on to the grass verge, airbag light went out and ABS started going out then flickering on when pulling forward.

Waiting to be collected since didn't want to risk re-occurrence on the 60mph road to home with few verges in pitch black, I started the car and drove to nearby car park. When I pulled up, I noticed all the lights above had gone off on the dashboard!

Must be a surge to kill both headlights at same time, so is my noisy alternator the trouble (found out it's noisy when sourcing loud whine from engine - seems to be the idler pulley bearing, new kit on way. Alternator sounded rough when spinning by hand during search for cause of whining)? Why did so many dashboard lights come on?

Not sure what to make of it or what I need to do to ensure it doesn't happen again!

hi , never heard of bulbs blowing! if it was a power surge of that extent it would have blown a lot more, did the belt come off ? if so this will bring on warning lights as all the on board computers will see low voltage and so bring on there lights! it does sound like an alternator fault if its noisy but it would have cooked the battery first as this will absorbe all the over charging from it! hope this helps as i have never heard of this before,

[JamesQB]

I've never heard of it either, but I have two bulbs in front of me with melted filaments that blew at exactly the same instant.

Each bulb is independently fed through its own 7.5A fuse - they aren't linked. I wondered if they took the brunt as being lower resistance by nature (pulling 55W of power), they might have taken any spike more readily than something with high impedance.

It's guesses though, because I only have 2 blown bulbs, the experience of the dash lights and not a clue what went wrong and if it'll happen again!

My plan of attack is to change alternator as its bearings sound grumbly anyway, and it scrapes a bit too when turning, and also to check all earthing points on the car, take them off, clean and rough up, silicone grease to protect, and back on.

[ODBODD]

Sounds a bit lik e the voltage regulator has packed up. This would cause a high load on belt also and slippage ,hence noise. I had tis on a Citroen a few years ago.

[JamesQB]

I bought a new alternator and fitted it today. Voltage from it is 14.2V, whereas old one was 13.4 once stabilised. I say stabilised because the car played up again the other day (no blown bulbs this time) and I was able to get a meter on the battery while it was still mucking about. Voltage was shooting from 13V to over 16V, possibly more variation but it's a slow-reacting digital meter, and the voltage changes were very rapid, jumping all over the place. Battery light was going on and off during this, as well as airbag light, ABS light, SERV light. Lights all went off once voltage stabilised.

Revving it didn't help, and the interior lights were dimming and getting brighter while it happened (very bright at points - too bright). Then all of a sudden it stopped and stabilised, stayed that way a while, then played up again. Now the old one is off, I was able to check it. Bearings knackered, with one missing the ball cage so the ball bearings are rolling around freely, clacking into each other. Turning it by hand it's stiff, rough and catches a lot. Haven't looked at brushes as need to send it off to get surcharge on new one back.

Loud whining noise was the idler pulley on auxiliary belt. Bought a kit of idler pulley, automatic tensioner pulley and belt. Fitting the kit has completely got rid of the noise. Idler sounded like an old roller skate wheel when spun, and tensioner was wobbling all over the place and had 3mm of lateral movement. It's now quiet and growls nicely when revved.

Time will tell if headlight bulbs now survive, but too late for the 3-day-old £20 Philips Xtreme Power I'd put in there originally...

[Synergietom]

just as a precaution i would change the battery as well as this would have been damaged to some extent from the power surge, to be honest this sounds about right if the power regulator on the altenator has packed up as it would blow fuses and bulbs before cooking the battery but said i would still change the battery as a mattery of due course just to be on the safe side.