Driver side daytime running light not working - 2017 Leaf S

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rodenti

Active member
Joined
Jul 2, 2017
Messages
30
I have a 2017 Leaf S (Canada model) and the driver side headlight burnt out. I replaced it with an H13 bulb and noticed that the daytime running light on that side is not working, although the low and high beams work fine.

I swapped bulbs from left to right and same issue. The passenger side daytime runner works fine, but not the driver side. Low and high beam work perfect on both sides.

Any ideas how I can troubleshoot and fix this problem?
 
The bulb only needs 12V and ground to turn on. If you have a DVM check for 12V with the bulb removed by putting the ground lead of the DVM to a known good ground (any bare metal attached to the frame should work).

If you have 12V then there is a problem with the ground, probably a bad bulb socket or a bad connection somewhere else. If you don't have 12V then there is a bad connection in that side. That could be a broken wire, a bad socket, a bad light switch, etc depending on how the circuit is wired. I doubt the running lights have separate fuses on each side but check that if needed.
 
Thanks, I'll give that a try. It just started to snow here so I'll have to wait until tomorrow.

The H13 headlight connector only has three wires - a centre ground, one for low, and one for high. This means there is no separate wiring for the DRLs. The fact that low beams work means the wire going directly into the connector should be good.

I assume the DRL is just a lower voltage sent to the low beam part of the bulb, so I'll pull out my multimeter and check the voltage with the car running with lights off (DRL activated), low, and high beam.

Should I have any concern about plugging and unplugging headlight bulbs while the car is running?
 
There shouldn't be any issues with plugging the bulbs in/out with the lights on but halogen bulbs get very hot when on and you shouldn't touch them with your skin as the oil on your skin can damage the glass. So use some clean gloves is possible.

It's possible the bulb housing itself is damaged, especially since the bad DRL is on the side that had the previously bad headlight. I don't know how the DRL's are wired in a Leaf but if the bulb does use a lower voltage it probably has a resistor in series to drop the voltage. If that's the case, that part may have burnt out.
 
Figured out the problem. We noticed that the factory driver side headlight was out so I bought plug and play H13 (9008) LEDs to replace them... they were the cause of the problem with the daytime running lights.

When I installed the LEDs the DRLs only worked on the passenger side, so I removed the drivers side LED and replaced it with the working halogen and the DRL still didn't work. I wrongly assumed the driver side DRL had a fault.

I installed a set of halogens on a hunch and now both DRLs are working.

It is very strange that the DRLs worked on the passenger side and not the drivers side with the H13 LEDs.

I'm curious if both DRLs would fail if the passenger side blew... is there a circuit that sends 12v through the lights in series through the passenger side then the drivers side when DRLs are in use to dim them? I'll have to try to find a wiring diagram for the Leaf to investigate.
 
Found a wiring diagram online for the Leaf and I think this confirms my deduction.

Power flows from the battery to the high beam lights through a high beam relay (SPST) and a DRL relay (SPDT - default to ground, activated to batt+).

When the high beam is turned on the HB relay is activated sending 12v in parallel to both high beams lights, with the drivers light going directly to ground and the passenger light going through the DRL relay to ground.

When DRL is turned on, the HB relay deactivates (switches off) and the DRL activates (switching the passenger side from ground to the battery). This results in the battery going through the DRL relay to the passenger side light and backwards through the circuit to the drivers side light, then to the ground on the drivers side. This results in lower light output since the lights are in series.

I have now tried two different LED sets, one lights up only the passenger side and the other doesn't light up either. I'm thinking that since they are diodes they don't allow the power to flow "backwards" to the drivers side light.

Here's a simplified text diagram (removing the fuses and CPU connections)
Code:
Bat _________________________
      |                      |
      HB                     |
     Relay              Gnd  /
      |____________       \ /
             |    |       DRL
           Left Right     Relay
             |    |________|
            Gnd

Here's the actual diagram with the DRL flow highlighted:
 
Thanks for the update. It makes a lot of sense and as if often the case, once you understand the problem it seems obvious. Nice job.
 
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