Hi everyone, 

 

Had a problem arise with my 2015 fiesta zs. The nearside dipped beam and only dipped beam has stopped working, all other lights work. Assumed a bulb at first but the new bulb never worked. Tried putting the known working bulb in, still no joy. 

Have metered the working light and non working light. 

~10.5v on both when lights are turned off. When lights turned on, the working side jumps to 11.5v but the side not working stays at 10.5v. 

 

Any suggestions what may be going on here? Fuses testing fine, as far as I'm aware the lights aren't fused separately? 

At a bit of a loss where to go next with this one. Any help appreciated. 

Remove the bulb from the non-working side. Then measure the resistance of the earth side of the holder to the battery negative terminal. It should be less than 1.0 Ohm

1 hour ago, unofix said:

Remove the bulb from the non-working side. Then measure the resistance of the earth side of the holder to the battery negative terminal. It should be less than 1.0 Ohm

Will do this first thing tomorrow. Weather is stinking here and been drenched through once already. 

So, say it is grater than 1ohm, what's the next step? 

 

Thanks for the info mate, appreciate the quick response.

1 hour ago, daz1412 said:

So, say it is grater than 1ohm, what's the next step? 

Then you are looking for a corroded wire/terminal. The earth point won't be very far from the headlight. Check that the earth contact on the holder is making a good contact with the bulb.

After that, it's likely to be water ingress to the Body Control Module (BCM) which controls and operates the dipped beam (but not directly the High Beam).