Hello, great forum. I have searched and could not find a similar thread. Both of my low beam headlights are out. I replaced the steering column switch, checked the fuses and all good. Tested continuity on the bulbs, both good. The horn works so I switched that relay with both of the headlight relays no luck. I pulled the bulbs on both sides and tested voltage at the pins. Each pin when measured against a valve cover bolt show 12 volts so this might be a problem.
When the car is running and the headlight switch off the daytime running lights work.

I have run out of ideas and would appreciate a suggestion. I fear it is a wiring problem and if so how could I test it. Thanks in advance!

 

Power to hi and lo beams uses same wires, however ground circuit is separate. Lo beams are always grounded (always on when light switch is on) and hi beams only grounded when commanded (stem switch). Check for ground at headlights and if absent inspect wiring and ground points G201 and G301 for possible problem.

good luck

 

Thanks TexasHonda for the quick response! Sorry for my ignorance but how do you check for ground at the headlights?

 

Checking for ground is like checking continuity on the bulb. Just touch one meter lead to the black ground wire on the bulb electrical connector and the other meter lead to a good ground (like valve cover bolt or the negative battery terminal)

 

You can turn the headlight switch on, disconnect the connector at one of the low beams and check to see if there is power there. If there is power there then you now know there is a break in the ground or corroded ground contact someplace after the light assembly which you will need to track down, or worst case scenario install a new ground wire.

 

Suggest checking ground resistance on lowest resistance scale. Connect VOM to ground pin at low beam bulb connector and to a known good engine ground. Resistance should be very low; < 1 ohm depending on zero calibration (resistance of probes touching together) results.

If several ohms resistance measured, then wire or ground connection to body needs to be serviced by removing, cleaning, and resecuring.

good luck

 

Thanks for the suggestions. I didn't have time last night to work on the car but discovered this morning that the daytime running lights are no longer working and the drivers side high beam is also out. Perhaps this is the tip of a major upcoming fault? I guess I should proceed with the recommended diagnostics and see what comes out.

 

I overlooked the bit about DRL (Canada car?). If DRL (low beam bulbs) are running when headlight switch is off, then low beam grounds are good.

If you have 12V to bulb pins with headlight switch On, then low beams should work.

Note, Auto Lights OFF could disable power to the head lights relay and disable low beams, however there would not be 12V on the bulb connector pins.

good luck

 

TexasHonda's initial post regarding checking the low beam grounds for the low beams is still valid.

The DRL uses the high beam bulbs at reduced voltage.

This is a description of how the DRL works:

Daytime Running Lights
When you turn the ignition switch to ON (II) with
the parking brake released, the DRL control unit
supplies about 6 volts to the ORN/WHT (cavity 10),
about 12 volts to the RED/WHT wire (cavity 1), and
ground to the RED/ORN wire (cavity 11). This
provides about 6 volts to both high beam
headlights, causing them to come on at reduced
brightness. If you apply the parking brake, ground
is applied to the DRL control unit at the GRN/WHT
wire. If the parking brake is applied before you turn
the ignition switch to ON (II), the daytime mode will
remain off until you release the parking brake.
Once the high beams are in the daytime mode,
applying the parking brake will not turn them off.
When you switch to low beams, high beams, or
flash-to-pass operation, ground is applied to the
DRL control unit through the BLU/RED wire, and
the control unit then turns off the daytime running
lights mode.

 

Thanks for the explanation on the DRL. This is a Canadian car btw. I'll do some more checks and report back any findings. Really appreciate the help from the contributors!