Main (high) beam fault

Gazdkw · May 20th, 2020, 22:05

I really need to get this fault sorted as my car is out of MOT.

The fault is that the fuse keeps blowing when I use the main (high) beam. Iv managed to get the beam to stay on whilst the car is running and was convinced I'd sorted it but next morning it blew on first use.

What's the best logical steps to diagnose?

seanc · May 21st, 2020, 08:57

I think you had a post about this before, I forget what you've been through, but have you checked all the grounds?

Maurice Mynah · May 21st, 2020, 08:59

Just a thought, Does the fuse blow if you flash your lights? I believe that's the full beam.

I don't know how easy this will be but I'd start by first checking the fuse is of the correct value, though you've probably already done that.

rxtian · May 21st, 2020, 09:53

Try unplugging the bulbs and see if the fuse still blows.

Gazdkw · May 21st, 2020, 10:18

Yep I posted before. Didn't really get to any conclusion. I'm going to throw myself into it now and fix it.

So, if unplugged the head units themselves and it still trips.

Iv not checked the ground connections. How doi go about this? Randomly look for ground connections or should there be specific ones in specific places? Even if there was a missing or bad ground connection, its only there for a fault to earth path? It wouldn't cause a fault itself?

Iv checked fuse rating and it is correct

Gazdkw · May 21st, 2020, 15:46

Iv managed to find the wiring diagram for high beam.

Fuse is F9. 15A.

Relay is K2. Soldered relay in CEM.

see the below thread, how would I go about diagnosing it's a relay or not?

https://www.volvoforums.org.uk/showthread.php?t=217111

May 20th, 2020, 22:05	#1
Gazdkw Master Member Last Online: Yesterday 18:49 Join Date: Apr 2015 Location: Leicester	Main (high) beam fault I really need to get this fault sorted as my car is out of MOT. The fault is that the fuse keeps blowing when I use the main (high) beam. Iv managed to get the beam to stay on whilst the car is running and was convinced I'd sorted it but next morning it blew on first use. What's the best logical steps to diagnose? __________________ 2008 XC70 2.4D SE

May 21st, 2020, 08:57	#2
seanc Member Last Online: Apr 17th, 2024 20:20 Join Date: May 2011 Location: East Cambs.	I think you had a post about this before, I forget what you've been through, but have you checked all the grounds? __________________ 2017 V60 D4 Geartronic

May 21st, 2020, 08:59	#3
Maurice Mynah New Member and total Prat Last Online: Feb 13th, 2021 15:43 Join Date: Apr 2020 Location: Harlow	Just a thought, Does the fuse blow if you flash your lights? I believe that's the full beam. I don't know how easy this will be but I'd start by first checking the fuse is of the correct value, though you've probably already done that. __________________ Volvo V70 SE Sport D5 Auto MY2008 (P3) on a 57 plate. For the less technical, It's a pale metallic blue one.

May 21st, 2020, 10:18	#5
Gazdkw Master Member Last Online: Yesterday 18:49 Join Date: Apr 2015 Location: Leicester	Yep I posted before. Didn't really get to any conclusion. I'm going to throw myself into it now and fix it. So, if unplugged the head units themselves and it still trips. Iv not checked the ground connections. How doi go about this? Randomly look for ground connections or should there be specific ones in specific places? Even if there was a missing or bad ground connection, its only there for a fault to earth path? It wouldn't cause a fault itself? Iv checked fuse rating and it is correct __________________ 2008 XC70 2.4D SE

May 21st, 2020, 15:46	#6
Gazdkw Master Member Last Online: Yesterday 18:49 Join Date: Apr 2015 Location: Leicester	Iv managed to find the wiring diagram for high beam. Fuse is F9. 15A. Relay is K2. Soldered relay in CEM. see the below thread, how would I go about diagnosing it's a relay or not? https://www.volvoforums.org.uk/showthread.php?t=217111 __________________ 2008 XC70 2.4D SE

May 21st, 2020, 09:53	#4
rxtian Senior Member Last Online: Oct 30th, 2023 18:03 Join Date: May 2011 Location: Southampton	Try unplugging the bulbs and see if the fuse still blows.

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