Finally figured out why my 2001 XC70 tail lights kept failing

[g0eppin]

So forgive me if this has been covered before, but I wanted to share what I've learned because I had no luck searching on the problem when I was trying to fix these.

It was time to get my wagon inspected to renew the registration, and around here they won't pass you unless ALL your lights are working. Judging by the number of XC70s I see around town with dead position lights and brake lights, I don't think I'm the only one dealing with this.

I kept replacing the bulbs, which we all know is the biggest pain in the ass considering you have to remove every interior trim piece to get to them, and they'd work, but by the time I got to the inspection station one or more would be burned out. Over many trips to O'Reilly and a lot of time with the manual, I finally discovered the problem isn't the car, it's the manual itself.

Either Volvo severely screwed the pooch on parts numbers in the manual or lamp producers have changed the specs since 2001, but the wattage on almost every bulb has gone up since produced. When I stopped buying by part number and instead by wattage and base style, I finally got a set of bulbs that have all been going strong for over six months. If anyone finds this helpful I'll dig up the part numbers for the bulbs that actually work, stay working, and don't get so hot that they melt the blades. The only one that's really difficult to find is the variable wattage fog light/position light on the driver's side - I finally compromised with a lower wattage bulb because I couldn't find one with the correct watts that also had the offset base.

[matthew1]

Great post. This is going in the Volvo Repair Database.

[June]

I realize this is a old thread, but I experienced the constant blowing bulbs situation with my P2 car 2004 S80.

I went through a rash of bulb failure including headlights. It was really driving me crazy. Years earlier the car wouldn't start at a inopportune time so I called AAA and paid them to install a battery meaning to have a Volvo battery put back during my next service, but the battery is out of sight under plastic in the spare tire well. You guessed it I forgot I had that wrong battery under there. A few years later the car was starting fine, but I had a rash of crazy codes and messages like alarm service with the occasional blinking lights no sound and bulbs blowing constantly.

It turned out the AAA battery was not the proper rating for my car. It was too light duty and over a couple of years had weakened causing the electric system to go haywire resulting in; alarm issue, several reoccurring codes, and the endless blown light bulbs. The correct Volvo battery went in and not another bulb has blown, codes never came back, and alarm functions normal never throwing the alarm message in the readout again.

All that mess because of a lighter duty battery that had weakened with age, but not enough to cause a starting issue. It's been a couple of years now and probably 40K so I feel confident that the correct rated battery cured the issue. June

[June]

I realize this is a old thread, but I experienced the constant blowing bulbs situation with my P2 car 2004 S80.

I went through a rash of bulb failure including headlights. It was really driving me crazy. Years earlier the car wouldn't start at a inopportune time so I called AAA and paid them to install a battery meaning to have a Volvo battery put back during my next service, but the battery is out of sight under plastic in the spare tire well. You guessed it I forgot I had that wrong battery under there. A few years later the car was starting fine, but I had a rash of crazy codes and messages like alarm service with the occasional blinking lights no sound and bulbs blowing constantly.

It turned out the AAA battery was not the proper rating for my car. It was too light duty and over a couple of years had weakened causing the electric system to go haywire resulting in; alarm issue, several reoccurring codes, and the endless blown light bulbs. The correct Volvo battery went in and not another bulb has blown, codes never came back, and alarm functions normal never throwing the alarm message in the readout again.

All that mess because of a lighter duty battery that had weakened with age, but not enough to cause a starting issue. It's been a couple of years now and probably 40K so I feel confident that the correct rated battery cured the issue. June

Okay, I looked and the Volvo OEM battery went back in August 2016 at 111K. I am at 146K and over a year since and no more blown bulbs. So that is 14 months and 35K without any more blown bulbs.

The complaint the car went in for was to stop the On Call message from being displayed without removing only half the phone. The car lights stayed on without the engine on just long enough in the mechanics stall to cause a starting issue. That is why the battery was even looked at.

I was thinking all the years of the lights being on because of the daytime running lights possibly damaging by overheating causing the problem. I was obviously wrong about that in hindsight.

I thought I would clarify that the crazy codes popping up, alarm message reoccurring on the dashboard readout, and crazy light bulbs constantly blowing all stopped after the new Volvo battery went back in the car. It in no way was the complaint I had the car in the Volvo Service Department for, just a happy side effect after the fact.

Also every bulb change has been done by Volvo. Yet still they kept blowing during that period of the weakened improper battery being in place.

Also I didn't start having those three side effects for the first couple of years the AAA battery was in there, only once it weakened to a certain point unnoticeable to the driver, but just about ready to leave you stranded. June

[Rattnalle]

How small was the smaller battery compared to the new bigger one?

A lot of petrol cars have quite small batteries to begin with even though the battery compartment is the same for all models including the heater equiped diesels which have much larger batteries.

[June]

How small was the smaller battery compared to the new bigger one?

A lot of petrol cars have quite small batteries to begin with even though the battery compartment is the same for all models including the heater equiped diesels which have much larger batteries.

I never saw the AAA roadside service battery. You can not see the battery on my car and a metal bar bolted down prevents the plastic box covering the battery from being lifted off to see.

It was explained by my service advisor Mike that the electrical value? Rating? Anyway say the car called for let's say a 900 rated battery the AAA battery was like a 600. I can't remember the exact ratings told to me, but it sticks in my mind it was 1/3 too small. I know all car batteries are 12 volts, but the rest of the ratings were like 30% less than the specific ratings for the battery correct for my car. It was explained to me that electrically would discharge too rapidly causing the charging system to compensate for the batteries shortcoming which shortened the battery life.

Also the point where the main cable from the battery in the trunk connects under the hood at a fuse panel cooked resulting in the fuse panel to be replaced and the starter cable too.

What makes since in my mind is this must have caused spikes in the electrical system bowing bulbs, and low voltage while off upsetting the alarm. June

[MarcM]

I replaced my Group Size 48 (H6) battery (650 CCA if I remember correctly) with a Group Size 49 (H8) battery (900CCA). There are two mounting spots for the hold-down bracket with the furthest mounting towards middle of car to fit this larger battery. I'm still having odd start issues, but that's because my crank position sensor is on the fritz (replacing Saturday). Car cranks extremely well. If you're in a cold climate, I recommend the H8/49 battery.