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Haynes’ World: Volvo V70 DRLs on the blink

Haynes World: Volvo V70 bulbs

Haynes' World is a regular feature that takes a look at what the people at Haynes are doing with their cars, bikes and other vehicles. This time, an intermittent Volvo daytime running light fault points to dodgy wiring.

Volvo V70 towing a trailer

Car: 2001 Volvo V70

Owner: Nigel Donnelly

I have been running a 2001 Volvo V70 2.4 for three years, and it has been one of the most trustworthy and comfortable vehicles I have ever owned.

I love its relative simplicity but among the few odd foibles it does have is a hunger for halogen lightbulbs. As a Volvo, it has daytime running lights in the form of permanently illuminated dipped beams at the front and always-on tail lights.

As a result, it gets through bulbs quite regularly but recently, there has been a persistent but intermittent warning on the dashboard, telling me a dipped beam bulb was out. 

Volvo bulb message dashboard

I popped the bonnet and then started to car to confirm which bulb was at fault – the dashboard warning message does not tell you which side is faulty, but that didn't take long to suss.

It was the offside front, but I noticed there was a lot of movement at the back of the bulb, where the terminals were attached. I started the car again and moving the terminal lit the bulb back up, so suspected a loose or dirty connection.

I cleaned the terminals, gave them a squirt of WD40, pinched the female spade terminals a touch to ensure a snug fit, dried them off and then put everything back together. The lights were all on and I packed up and headed indoors, presuming I'd done enough.

Light bulb terminals

The next day, I jumped in the car and was met with the familiar telltale orange warning triangle on the dashboard and the message about a dipped beam failure.

I removed the dust cover from the rear of the headlamp, touched the bulb and it lit up again. It needed a closer look. Access to the rear of the offside headlamp in a V70 is a little snug, but a quick prod about revealed no chafed cables, loose grounding or any other culprit.

With nothing obviously amiss, I decided to get a second opinion, stealing part of colleague Martynn's lunch hour to get a second pair of eyes on things. 

The first thing Martynn noticed was that the terminals were tight enough on the fittings, but that one of the fittings itself felt loose. He suspected a failure of the bulb's structure, rather than the more common burned-out filament. As a result, he was worried that removing the bulb might leave me without a headlamp at all if it couldn't go back together.

Spare H7 bulbs onboard

With a drive in the dark of around 200km in prospect, that wasn't a good idea. Three years of Volvo ownership have taught me well, however, and I always keep spare bulbs on board. I showed Martynn the stash in the boot, and among them was a spare pair of new H7s, so if we ruined the old bulb getting it out, we at least had a new one to replace it. 

Martynn removed the bulb for a closer look. On inspection, the reason for the intermittent illumination became clear - the base of the bulb had broken. It was pretty black, cracked and heat-fatigued. The flickering convinced me I was looking for something more involved. The broken base meant one of the terminals was floating about and only occasionally making sufficient contact to light things up. 
At least it meant the fix was easy. I thought we might be looking at new cables or something fiddly to track down, but in the end, a new bulb was all that was needed. The new bulb was fiddled into place in the small gap between the ECU housing and the back of the headlamp. I headed off to the shop to replenish my spare bulbs store.