Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

Low beam only working when high beam are turned on.

Darkness1990

Member
Joined
Aug 11, 2019
Messages
40
Reaction score
8
Points
8
Age
31
Location
Boronia Heights
Members Ride
VY Commodore 3.6 ecotec
hi, so I've check forums seems to be pretty common problem but no solutions so thought I would mention, I just changed the alternator once job was done I noticed my low beams don't work but they work when I put high beams on. I've checked fuses, relays, bulbs, switch is engaging when I flick it on and off. I should also mention I have a multimeter but no idea what to check for or where to check. Checked wiring. Im lost as what to do next.... Please help!
 

Trevor loves holden.

Well-Known Member
Joined
Jun 6, 2019
Messages
3,429
Reaction score
743
Points
113
Location
Victoria
Members Ride
vs commodore
Sounds like a earth problem from the light harness. They activate using earth so my guess the high beam is giving it the earth it needs.
Oh you do realise they have a high low so maybe the low filament is broken.
 

immortality

Can't live without smoky bacon!
Staff member
Joined
Apr 15, 2006
Messages
17,402
Reaction score
6,978
Points
113
Location
Sth Auck, NZ
Members Ride
HSV VS Senator, VX s2 Calais S/C
I had a similar problem. It started with a broken and damaged wire in the headlight, all fuses and relays were good. Still after fixing the wires my fog lights would come on (faintly) with the headlights and one headlight was a bit dull. Turns out one of the fuses was blown (probably occurred when repairing the broken wires).

Another issue may be the high beam switch as the low beam is switched off when the high beam is turned on.

Trev, the VY headlights are different to your VS. VT onward uses separate bulbs for the head light and high beams which is a bit different to your H4 bulbs.
 

axemurderer101

Well-Known Member
Joined
Jun 14, 2006
Messages
1,883
Reaction score
135
Points
63
Location
Albany
Website
forums.justcommodores.com.au
Members Ride
VY SS
My bet is the globes are just blown, low beam is a h4 which is a high and low beam in one globe which is why it lights up when you flick to high beam. Sometimes when they are blown the filaments can still look ok, post a close up pic on here if you are unsure.

You could also try swapping the low beam relay with the horn relay to see if its a faulty relay.
 
Top