07 Volvo S40 HID issue

9394volvo850s · Post by **9394volvo850s** » 25 Apr 2011, 21:39

My girlfriend has an 07 S40 T5 AWD. I got her a set of hids for her birthday. they work but not if the car is running... lol. if the ke is in the #2 pos. hids come on and work great. once the vehicle is started they come back on then they do dim and start fickering like crazy and dont stop. i have installed many hid kits in the past and have never seen anything like this before, these were suposed to be anti flicker kit. could that be causing a problem?

Post by **jimmy57** » 25 Apr 2011, 22:53

2005 and later volvos have voltage controlled lighting. The voltage to headlamps is limited to 13V. The transistors powering the lamps circuits start pulsing a percentage of time off to limit voltage and the ballasts on that light kit are probably going off on each pulse. I think the frequency of the pulsing is 70 Hz or maybe even more. For filament bulbs it's no problem. Factory HID's have a different power supply as the regulation is not needed for longer bulb life for those.
You will have to use relays for the ballast power supplies where the power supply in is battery fed and the relay coil can be run by the feed normally used by bulb. I think you already have bulb failure warning on cluster but if not you will when you get the HID's re-powered. Technology is not always kind nor do engineers worry too much about aftermarket items when they design cars.

9394volvo850s · Post by **9394volvo850s** » 26 Apr 2011, 15:23

ok so what kind of relay do i use? can i just bypass the voltage regulator going to the headlights?

Post by **jimmy57** » 26 Apr 2011, 18:54

Standard relays, one for each lamp.
There is no voltage regulator. The control unit that turns on lamps and a lot of other things does it via circuit board mounted transistors. If voltage is below 13 the transistors are on 100%, if voltage goes above the percentage falls below 100% with the rapid cycling off time reducing the voltage to bulbs. The current draw through transistors is used as bulb failure detection. You will need to use the bulb circuits to power relay contact closing coils and you will have to come up with an appropriate resistor to load the circuit of the bulb out message will be on any time headlamps are on.

9394volvo850s · Post by **9394volvo850s** » 30 Apr 2011, 19:52

thanks i swapped ballasts with a friend and its fine. no flckering

the ones i was using were digital slim. i swapped 2 the older big ones. its fune now.