headlight not working

noticed yesterday the right headlight was out.
driving back both headlights went but main beam and side / brake lights still worked.

had a look today and the bulbs are fine, checked the fuses and they were good too, took the drivers side out and wiggled and placed it back in and it now works.

but the passenger side light still wont come on, when seating it back in the light socket it does briefly flash on which makes me think its a ground issue?

put a meter on it and it read 10.40v, i was expecting to see 12v but I'm not sure what the voltage should be for sure?

anyone encountered this before?

 

There's something wrong if you only have 10.4VDC you should see battery voltage.
Did you measure the voltage with both meter probes in the connector, or between the connector & a ground on the body or engine?

 

measured against ground on the body, as the connectors a bit tight to get the probe on to.

 

Happened to me a couple of months ago
Have a look at the ground wire on chassis in engine bay

 

The RED wire with the BLACK tracer is the + wire & is common to both the high beam & the low beam, so they should show the same voltage.
It is also common to the right side lights.
The - wire for the high beam is WHITE & goes from the globe to the dimmer relay.
The - wire for the low beam is GREEN with a YELLOW tracer & goes to the dimmer relay.
The green/yellow wire is common to the left & right headlights, so if the right light is working the relay is OK.
Perhaps the issue could be the connector, or the two wires connected to the left low beam headlight

 

Incorrect information!

Correction:
The + wires to the right side lights are RED with a GREEN tracer.
The other information is correct according to the circuit diagram.

 

so I checked the ground cable from connections to the body and the engine and they look ok.

checked the bulbs connected with a meter and they are at 12.5v

if i touch the bulb metal housing against the car body they turn on ( can take a few taps) , and continue to work (turn on and off from the switch)

but the either one or both will turn off seemingly at will... :/

do the metal retainer clips some how maintain ground?

 

.. and now the bulb has blown... joy :/

 

The blown globe could've been the issue.
As far as the globe earthing through the housing.
The dimmer relay switches the ground (-) from low beam to high beam.
Unless the wiring has been modified for HID's, the OEM configuration is as follows.
When low beam is ON high beam is OFF.
When the high beam is ON low beam is OFF.
If the globes were grounded, then the dimmer relay would be ineffective.
So your 'tapping" the globe was probably "improving" a bad connection.
The globe may of been the bad connection, or the bad connection may still exist in the connector or wiring.
Test for resistance in the circuit using OHM's or Voltage Drop.

 

thanks for the help east coast z

replaced the bulbs and looks to be resolved, so heads up anyone that gets a similar issue.

I will be replacing the battery cables soon as they are long overdue some new terminals and cable.