Wiring problem on front side light

[thebandit92]

My front n/s (drivers) side light and side marker lights don't work,both are also indicators and both work ok when indicators/hazzards are switched on.There is power at both bulb holder connectors,although not sure how many volts as i can't find my digi meter.
When i turn sidelights on the l/h indicator light on dash light up,so am i right in thinking i have a short somewhere? All the rear lights work fine.
When i switch my radio on all the buttons light up and stay on even when i switch ignition off,don't think it is linked to light problem as it's wired straight to two connectors in fuse block,it's also connected to same power wire as my gauges but they go off with ignition,so had to disconnect radio.
Lights are my main problem as i want to take it for a MOT.Just not sure how to test for a short.
Seems odd the other side is ok as they are both on same brown wire,so wondering if it's a problem with indicator wiring?
Not checked my book but on my colour wiring chart it don't show a fuse for front lights,just tail so pulled every fuse out one at a time and kept checking indicator light on dash but it stayed on each time i pulled a fuse.

[nigel]

I think it's light blue for drivers and dark blue for passenger side that's the hot wire for front and side markers check for bad ground 1st, there are grounds on the front panel top corners but you do need a continuity tester to fault find.

[bhm1712]

There is no fuse for the front lights (sides, dip and full) they are supplied through an overload built into the headlight switch a assembly.

I'm not at home but let me have a think about this for a minute and I'll get back to you

[bhm1712]

right this is a mental overload but....

Originally the "side lights" were never called side lights they are parking lights. The first position on the light switch is the "parking" position. The supply for the front parking lamps (side marker and what we now call side lights) is on the brown wire at the bulb holder. The light blue is the turn and hazard flasher supply. Black is ground at the side light bulb holder and the marker light shares the same ground to a degree (see further down).The IP indicator tell tale is also supplied from the same light blue cable but further back at the main body harmonica connector on the back of the fuse box.

GM did some weird magic to get the side markers to flash all be it out of phase with the front indicators by having no fixed ground at the side markers. When the parking/sides are on the markers ground through the front indicator filament which is off (low resistance so provides good ground) and then when the turn/indicators turn on the current flow the opposite way and so the ground through the filament is removed and hence the side marker flashes out of phase with the front indicator signal.

With your tails working fine (fed from same contact at headlamp switch) , and the indicators/hazards working fine on their own but not with the sides or headlights on, this points to a missing /bad ground at the front indicator bulb holder in my opinion. The instrument panel indicator tell tale will be coming on with the headlamps as the current will be finding the least path of resistance to ground through.

Start by checking the bulb holder and associated grounds, it may even be a badly seated or bad bulb.

[bhm1712]

Just as a warning , the above is true for factory wiring. If it has been modded the above may not be accurate but still would be symptoms of bad grounds or bad bulbs/holder

[thebandit92]

Thanks for the advice,i will check my ground wires,i did take a wire direct from negative on battery to negative at side light bulb holder as i thought it was the holder at fault but it still didn't work.Gonna buy another digital tester today,probably find my other one once i buy one. Actually i have 3 digital testers but can only find one,and it's the one that don't work

[bhm1712]

Try a different bulb holder and bulb as well.

Let me know if it still doesn't work.

[thebandit92]

Try a different bulb holder and bulb as well.

Let me know if it still doesn't work.

Sorted,it's bulb holder Well,not really sorted as i don't have one.I had a rear stop/tail holder in the shed so connected that to the earth and side light wires as i had spliced into those wires,but side marker didn't light so touched the indicator wire from the rear bulb holder i was using and touched it to the connector inside the bulb holder on the car and marker light worked.
Gonna see if i can bodge something up with it so i can take it for a MOT on tuesday.
I did think it was the bulb holder at first but when i put my multimeter to the connectors in the holder it showed both had power,that's what then made me think it wasn't that,but the tester i used didn't show properly what voltage was there.

[bhm1712]

Great!

[bhm1712]

its usually always a fault with the bulb holder/grounds with this kind of issue.

I would imagine the bulb holder had internally corroded or the track broke.

[thebandit92]

Managed to pull the terminals out of the holder,they looked to be in good condition,earth one was a bit green so cleaned that one up,soldered a bit of yellow wire on the side light as i didn't have any brown and soldered a piece onto the earth.Working fine for now and will get it through MOT,but gonna buy a new holder.

[SUPERCHARGEDGTA]