2015 Ford Fiesta - Low beams intermittent

[KentuckyTexan]

My wife's 2015 Fiesta has a light issue. whenever you start the car, both low beams work will work for a few minutes before both low beams start to turn off at random times. Right when the issue is about to start, a small repetitive click can be heard coming from the engine bay. It goes away, then both lights remain on. light clicking begins, both low beams will randomly shut turn off then reappear once again. What's the issue?

 

[Handy Andy]

Hmm...The lights themselves - are always supplied power thru the main power relay when the engine is started. The lights go out when the engine is shut off or the light switch control knob is turned to OFF - you have the final say, but when you turn off the ignition - unless AUTO (A) is set on the control - the lights also go out.

If you encounter a flickering then they stay on, does this occur as you drive? I'm trying to help in thinking if vibration of driving is causing this - then the under the hood Engine Fuse block might need to be investigated. There are also grounding points for the harness and the lamps - but the LAMP switch HAS the Ground wire or main return - so if the lights flicker - two places to check - press down all the relays and fuses in the engine compartments fuse block and also locate the light switch inside and see if it's knob is loose. As you operate the switch (do this when the engine is running so you can try to recreate this) try tapping or flexing/Torqueing on the knob thru the turning range and see if the condition can be repeated or even occur.

It is my thoughts that either the wiring harness in the engine compartment needs some service or the light switch is nearing the end of it's service life or it somehow got kicked or "took a knee" when someone got in the car - loosening the knob from the index shaft and now it makes an intermittent connection until the tiny spark of current can spot weld the contact on until it's shaken loose by rotating the knob back to off.

Setting it to Auto won't help because if the shaft is damaged, the switch will just be as intermittent on Auto as if it were on any other setting except off.

So you can always force the Auto function on by jumpering the wiring harness and deal with the car wanting to run lights in Auto all the time - but if you're doing this to save the electrical and battery - you'll need to verify it's not the switch or the fusebox causing this.

 

[scotman]

Sounds like a relay is failing. Or possibly some wire in that circuit is exposed and shorting!
Has the car ever been in a front collision?

 

[KentuckyTexan]

Hmm...The lights themselves - are always supplied power thru the main power relay when the engine is started. The lights go out when the engine is shut off or the light switch control knob is turned to OFF - you have the final say, but when you turn off the ignition - unless AUTO (A) is set on the control - the lights also go out.

If you encounter a flickering then they stay on, does this occur as you drive? I'm trying to help in thinking if vibration of driving is causing this - then the under the hood Engine Fuse block might need to be investigated. There are also grounding points for the harness and the lamps - but the LAMP switch HAS the Ground wire or main return - so if the lights flicker - two places to check - press down all the relays and fuses in the engine compartments fuse block and also locate the light switch inside and see if it's knob is loose. As you operate the switch (do this when the engine is running so you can try to recreate this) try tapping or flexing/Torqueing on the knob thru the turning range and see if the condition can be repeated or even occur.

It is my thoughts that either the wiring harness in the engine compartment needs some service or the light switch is nearing the end of it's service life or it somehow got kicked or "took a knee" when someone got in the car - loosening the knob from the index shaft and now it makes an intermittent connection until the tiny spark of current can spot weld the contact on until it's shaken loose by rotating the knob back to off.

Setting it to Auto won't help because if the shaft is damaged, the switch will just be as intermittent on Auto as if it were on any other setting except off.

So you can always force the Auto function on by jumpering the wiring harness and deal with the car wanting to run lights in Auto all the time - but if you're doing this to save the electrical and battery - you'll need to verify it's not the switch or the fusebox causing this.

So I actually ordered a new light switch for the interior and it didn't do a thing. The high beam is permanently out on the passenger side and has been out for some time (bought a new headlight and that didn't fix it either, so I sent it back). The low beam on the passenger side was the first to go out but the driver's side would actually still run like normal including the high beam. Now both low beams will go out intermittently. They stay on for a few minutes, then turn off (even with the lamp switch ON, not on AUTO), flicker, then remain on once more for a few minutes and it does the cycle again. However, the high beam on the driver's side functions normally. I've checked the relays in the engine compartment and they all seemed fine.

I can't tell whether it's a fuel injector, but when the engine runs, there's an additional and very quick successive ticking coming from, it sounds like, between the engine and the battery. It's on the right side if you're facing towards the car at the front. But when I turn the engine off, and leave the light switch on, no noise, but the lights still will do their on and off dance. Oh, and this problem happens not matter if I'm driving or sitting in the driveway or parking lot. Can't drive it at night but it runs no problem. No engine vibration or weird noise coming from the engine itself. We had a timing belt and crankshaft wheel replaced a few months back.

 

[KentuckyTexan]

Sounds like a relay is failing. Or possibly some wire in that circuit is exposed and shorting!
Has the car ever been in a front collision?

It has not. I've pulled the relays and they seem fine. I'm at a loss. I tried replacing the light switch as well. You can check my reply back to Handy Andy for a recap of the full symptoms.

 

[scotman]

Trace the headlamp grounds. Given that it is going on eight years old. Kentucky does get some winter type of season. Was the battery replaced in the recent past? If so, was the car driven for some time where it had to be jump started in order to get it started? It's possible that the BCM is failed.
At some point, relays, switch, power distribution box or grounds that circuit is interrupted.
Being 1,200 miles away. I can't take a multi ranging voltmeter and a flashlight and check out the headlamp circuit. So this is just guessing.

 

[Handy Andy]

There are several pigtails that "bolt" to the side of the engine compartment - these may be the very wires that ground your headlights back to the vehicles body and the battery cable return takes care of the rest.

​

IN the above, the locations are for simple bolt to side - but as you can tell by the various directions I had to take these shots, the Ground Points are in different locations to obtain the "main ground return" to the battery from the side of the engine compartment - all tie back to the main ground at the battery cable negative and if you can, use a conductive thread sealant or protector to help keep the connections working well for a longer service life.

The Right Headlamp might need to be removed to obtain access to get at that spot to even check the condition of the bolt to frame.

The Battery and its tray have to be removed to fix, repair or reseat the other grounding connections the front bumper needs and ties together to this frame bonding point.

 

[KentuckyTexan]

There are several pigtails that "bolt" to the side of the engine compartment - these may be the very wires that ground your headlights back to the vehicles body and the battery cable return takes care of the rest.

View attachment 5985​

IN the above, the locations are for simple bolt to side - but as you can tell by the various directions I had to take these shots, the Ground Points are in different locations to obtain the "main ground return" to the battery from the side of the engine compartment - all tie back to the main ground at the battery cable negative and if you can, use a conductive thread sealant or protector to help keep the connections working well for a longer service life.

The Right Headlamp might need to be removed to obtain access to get at that spot to even check the condition of the bolt to frame.

The Battery and its tray have to be removed to fix, repair or reseat the other grounding connections the front bumper needs and ties together to this frame bonding point.

So I should mention that I did replace the stock bulbs with LEDs in the vehicle. I don't remember for sure if the passenger side bright was out at that point yet, this was back in July. But the LEDs are 120W while the stock bulbs are 55W. You think they're pulling too much juice?

 

[Handy Andy]

No, the opposite really.

LED's are DIODES and Solid State - so the lamp that these replace, are not incandescent filaments and would draw far less current for the RATED lumens "wattage" comparison.

They use Dropping Resistors and consume far less current - and voltage across them - which requires the system that these are internally powered by, to limit voltage and current so the diodes don't blow up. They distribute power (these IC's and regulation systems internally to the headlamp) to the LEDS in several different ways the makers set them up for - so they don't provide a schematic so the system being self-contained and may instruct you that it will need some type of "sensor" or load placed across the power input (supply rails) to make it appear you have a headlamp installed.

Now that may have a say if the PACKAGE these came in, required a BALLAST - or LOAD Resistor placed across them. That is usually a 5Ω-ohm to 8Ω-ohm to as high at 10Ω-ohm resistor that is placed across the wires to the LED unit. The BCM (Body Control Module) system then sees a load and isn't confused by the load/no-load condition the LEDS are seen as by systems that monitor the current in the wires to the headlamps.