Headlights go on and off randomly during day.

jpeter · Post by **jpeter** » 21 Jan 2018, 20:42

Another issue with my 2004 XC90.

The headlight flashes randomly without any input even though the light switch is at 0 but works fine when the switch is turned to the on position. The problem disappears after driving around for sometime. Also, I am unable to select the hi-beam mode (it automatically switches back to low-beam). Please help.

Post by **June** » 21 Jan 2018, 21:30

Unsure of the off and on part, but on my 2004 S80 the high beams do the same when the switch is at 0 and work fine in the on position. I leave the switch in the on position at all times since the car is equipped with daytime running lights.

My 2002 S80 T6 had HID headlights option and turned off and on with a light sensor on the dash rather than staying on as the daytime running lights. June

jpeter · Post by **jpeter** » 21 Jan 2018, 21:42

My car is not equipped with the DRLs and driving around with headlight on during daytime can attract a fine here in Qatar I believe. I am getting angry stares from others due to this stupid inadvertent flashing. Sheesh!!

Post by **RickHaleParker** » 22 Jan 2018, 02:45

Sounds to me like your DRL are intermittent or the flash to pass/headlights are coming on when it should not be coming on.

On the 2004 I think the DRL is turned on/off in the Central Electronic Module (CEM).
If it is flash to pass/headlights coming on, that could be flaky wiring or flaky switch.

Also, I am unable to select the hi-beam mode (it automatically switches back to low-beam). Please help.

Position 0 is off with day time running lights where required or turned on where not required.
Position I is low beam driving, the stalk is flash to pass.
Position II is high beam driving, the stalk is High/Low.

jpeter · Post by **jpeter** » 22 Jan 2018, 04:10

In my case,
Position 0 all lights are off ( flash/pass light keeps flashing randomly, it subsides after driving around a while but tends to return if the car is switched off and started again).
Position I Just the park lights.
Position II Low beam turns on and switching to high beam via the stalk (but as you pull the stalk towards the steering wheel, it doesn't stay in high and goes back to low beam). Looks like my car doesn't have DRL.

Just had Bosch Service Center inspected and they told me it could be the ballast (I am not convinced). Rick, as you mentioned, it might be frayed wires. Will keep posted.

Post by **June** » 22 Jan 2018, 11:06

jpeter wrote: ↑22 Jan 2018, 04:10 In my case,
Position 0 all lights are off ( flash/pass light keeps flashing randomly, it subsides after driving around a while but tends to return if the car is switched off and started again).
Position I Just the park lights.
Position II Low beam turns on and switching to high beam via the stalk (but as you pull the stalk towards the steering wheel, it doesn't stay in high and goes back to low beam). Looks like my car doesn't have DRL.

Just had Bosch Service Center inspected and they told me it could be the ballast (I am not convinced). Rick, as you mentioned, it might be frayed wires. Will keep posted.

If it is the high beams that flash, it seems to me to more likely be the high beams switch getting flakey. My right turn signal is flaky every now and then. I found if I run the stalk up and down quickly like fifty times, the right signal works fine for a good half year. Like the signal stalk might have a bad contact. Maby if you flip the high beams quickly like 50 times and suddenly it stops for a while you'll know it is the stalk that is bad. What can it hurt? June

Post by **mrbrian200** » 22 Jan 2018, 13:11

Probably the stalk/switch. My experience with my own car ('06) makes me think a possible culprit might the white grease volvo uses on chassis moving parts (latches, switches, hinges, door stops) has hardened into a thick putty and sticking the mechanism. However, there is an small circuit board on the side of these with a few SMD components...capacitors, transistors, resistors... which raises the possibility of small component failure on the board such as an intermittent shorting capacitor or resistor fooling the logic into thinking you're pulling on the stick (replace it).

jpeter · Post by **jpeter** » 23 Jan 2018, 19:40

mrbrian200 wrote: ↑22 Jan 2018, 13:11 Probably the stalk/switch. My experience with my own car ('06) makes me think a possible culprit might the white grease Volvo uses on chassis moving parts (latches, switches, hinges, door stops) has hardened into a thick putty and sticking the mechanism. However, there is an small circuit board on the side of these with a few SMD components...capacitors, transistors, resistors... which raises the possibility of small component failure on the board such as an intermittent shorting capacitor or resistor fooling the logic into thinking you're pulling on the stick (replace it).

Thanks. Where would this circuit board be? In the on/off switch?

jpeter · Post by **jpeter** » 23 Jan 2018, 19:43

Also of note, whenever this happens, there is a bit of delay in the engagement of the turn indicators. Switched the headlight relays on the CEM with no effect.

Post by **mrbrian200** » 24 Jan 2018, 01:49

The circuit board is integrated into the switch/stalk assembly down in where the harness plugs in. The board doesn't look terribly complex but there is a little more than simple mechanical switches down in there.