Hey guys

​​Im trying to figure out where to start on troubleshooting why bulbs keep burning out on my XC90. I'd say I'm losing an average of one a month, and it's not specific to any one part of the car. I just swapped out both headlamps, and I've had a brake light out for awhile now, and just had a rear foglight go out 2 days ago as well. It's been like this for a couple years now, and I just wanna know where to start with ruling out the most obvious culprits before bringing it to a shop and paying someone else to do the same thing. Any help would be appreciated.

Kyle

 

Your (original) bulbs are 17 years old. The incandescent ones are going to burn out. Bad/dirty connections are going to form. You could replace ALL of your bulbs at once and possibly expect to not have to replace any for a few years - or replace them as they burn out.

During a major service we check all the exterior lights. It's not uncommon to find 5 to 8 bulbs out in xc90s near that year. (will always find the front marker and parking bulbs out)

A shop is not going to find anything other than a way into your wallet. Sure it's possible the charging system is overcharging - but you would have gotten some other hint for that. (check the charging rate yourself with your $10 volt ohm meter you keep in your house to check batteries and stuff)

 

I've replaced both headlamps alone 3-4 times over the last couple years though. So we're well past the original bulbs. I've heard that having to change them more often on Volvos is a thing, but regardless, my case seems ridiculous. So short of swapping every bulb and hoping for the best, where is the next most obvious place to look? And how do I go about checking the charging rate?

 

buy a simple volt/ohm meter at Harbor Freight or Amazon. No need to over spend since you only need to see .1 Volt differences... Now with the engine off, test the battery voltage at the terminals. You should see 12.6 to 12.8V. Start up the car - with any accessories (lights/heater/radio etc) off. You should see something in the 14 to 14.5 V range. Now turn on all your accessories - high beams, AC blower, rear defogger etc. You should still see something in the 13.5 to 14 V range. Next set the accessories to something normal (like day time running lights etc). For newer cars you may see the voltage periodically step down once the battery voltage comes back to something closer to a full charge (ie 12.8V).

As an alternative, you can also buy an OBD2 scanner which has run time data monitoring. Some like Foxwells will track battery voltage. You can plug that into the OBD2 port (usually under the driver's side of the dash - kind of looks like an old school printer port about 3 inches x 1/2 inch. Turn the key to position 2 and it will start reading data and give you monitor options including scanning for codes or capturing/monitoring run time data. The latter is useful if you want to do a driving loop but scanning for codes is a good idea as well

If at any point you see something over say 15V, you have an over charging condition and may need to further test the voltage regulator.

 

This is super helpful. Thank you!

 

By default your headlamps are on all the time. (on most of the cars) You can change that to make the bulbs last longer. (on most Volvos) Another problem (with the H11 bulbs) is melted connections at the bulb. The original plastic connectors have been upgraded to ones (hopefully) less likely to melt at the bulb connection. Changing the daytime running lamp function requires Vida and a dice unit or compatible interface. It can be done without a subscription using the easy to find for free Vida version 2014d. Expensive scan tools (shop level) might be able to do this also.