Help to know the year and model. I'll guess a 900 series model as you mention you have a US Market 945 estate / wagon.

The bulb out sensor uses what are called Reed relays. For your RWD 900 series there are several reed relays in the bulb out or bulb malfunction sensor. One circuit path brings power to the sensor for the low beam headlights. In the bulb out sensor, the low beam circuit is split into left bulb low beam filament and right bulb low beam filament.

It is a current draw imbalance between the left and right low beam circuits that bends the pass Reed relay to make contact and light the bulb out ash light.

The high beam filaments do not pass through the bulb failure / out / integrity / malfunction sensor.

See the Mitchell Service electrics diagrams here at this site:

http://www.v8volvo.se/mekartips/volvo/index.html

As the low beam circuit splits inside the bulb out sensor, the left and right positive route through a unique fuse for left and right low beam filament through the fuse box in the center console behind the ashtray.

The RWD 700 / 900 series fuse box is a service item as the bonded contact between the ATC fuse blades and the fuse box contacts the fuses secure into. With age and ambient conditions corrosion can form and heat builds causing plastic bits to melt. High current fuse contacts like climate control.

The headlight relay in your RWD 900 series enables your to use the front floodlights with low beams only.

FAQ: Electrical: Lighting, Horns
https://www.brickboard.com/FAQ/700-900/ElectricalLightingHorns.htm

FAQ: Electrical: Circuits, Wiring, Relays, Switches
https://www.brickboard.com/FAQ/700-900/ElectricalCircuitsRelays.htm

One solution is to connect the low beam out downstream, if you will, from the fuse left and right into a unique fuse or double pole / double throw fuse relay with B+ from the battery B+ rail powering the bulbs. Useful for the factory set-up or if you choose the high current HID system.

The factory US market square headlights, like on my three 240s, use the 9004 bulbs for the US DOT spec lens and headlight reflector assemblies. You are correct in that the beam pattern is not well focused. Also, these terrible assemblies can lose the water tight adhesion between the lens and reflector assembly. On plastic lenses like on all 1986+ 240s and some 700/900 models in the US market, these assemblies can form a fogging of the lens and limit the poorly focused beam down the road. On glass lenses used on 700/900, the glass lens can crack. In all instances, the reflector can be damaged.

On 1986+ US market 240s, the exterior lighting is problematic. The 700 and your 900 series use the combo filament 1157 for park and brake light. The right side uses a white bulb holder and the left (driver) side uses black for the 1157.

You can replace all exterior lighting with LED bulbs.

Some will place the bulbs into the wrong bulb holders and than again into the wrong tail light socket. It can cause problems if fitted with a flexible circuit board. The wrong bulb and bulb holder can ruin the circuit board, the bulb holder and the lens from excess heat. Some 700 / 900 do not use the park / brake light dual filament 1157 bulb.

On my 1992 240 GL, that uses the same bulb failure sensor (Volvo PN 1362370) as your 945, I bypassed the entire sensor.

I did this as the sensor uses sort of small diameter conductor for the low beam headlamps. Dave Barton's site has a kit to bypass the sensor after removing it from the wire harness socket and short conductors plug into the socket.

I trimmed the sensor assembly from the sensor socket base and soldered a heavier stranded copper conductor with high temperature and durable insulation to the internal side of the sensor socket base using appropriate temp lead / tin (Pb/Sn) solder. (To upset the RoHS lead-free folks. Ha!) All exterior lighting is brighter as a result. Like tire pressure and fluids I check all bulb including blinkers / flashers regularly.

See this page to read Dave Barton's three part article on the bulb failure sensor. Page (copy and paste URL into new browser tab or window):

https://www.240turbo.com/volvo240mods.html

The Volvo factory bulb out sensor bypass PN 1308561 is NLA. Held one in my hands once at Brentwood Volvo in Saint Louis in the 1980s.

You want the:

<<< Red Sensor 1362370: Diagram at left is for the RED 1986-93 bulb failure sensor (1986-93 240, 1986 and later 740, 780, and 1991-94 940). 
Diagram view is facing contact pins. The diagram is sort of small:



Our Art Benstein has a diagram for this or the earlier black bulb sensor (pre-high center third brake light) someplace. I did not find it at first glance at Art's site cleanflametrap.com. I had to use Art and Dave's diagram as I am a terrible dyslexic when bypassing the sensor on my 1992 240 GL.

Art's diagram is here in this Turbobricks thread:

http://forums.turbobricks.com/showthread.php?t=240085

I may go to LED for the stock 240 headlight housing. I used Eclectic products RV or Marine Goop to seal and secure the lens to the reflector assembly. With new halogen bulbs and clear lenses and fine reflectors after the cleaning and reseal, the US DOT 1986+ 240 headlamp lighting still sucks. So brighter LEDs for all. Someday maybe e-codes. Miss the sealed beam dual round and quad round set-up on my 1970s 240s. Miss K-Jet and that era sometimes.

Questions?

Hope that helps you!

Merry Christmas!

Eggnog and Fruitcake Boyyyyyyyyyeeeeeeeeeeeeeeeeeeeeee!!!!!!




--
Beh.