Both Lowbeams Suddenly Stopped Working
 

Hey everyone,

About 2 days ago both of my lowbeams stopped working at the same time. I replaced fuse 56 and 57 (right lowbeam and left lowbeam) in the box next to the battery. I replaced the battery fuse as I've heard that is where the low beam relay is contained. New bulbs were also tested, didn't work. Stumped about what I should replace/test next, am I overlooking something obvious?

Have you checked the bulbs themselves? I've seen people have both go bad at the same time. I've also seen people think both went bad at the same time, but they really were driving around with one bad one for awhile, then the other went out.

There might also be a relay for the low beams. Different car altogether, but I had a Grand Prix that I was driving one night and suddenly the low beams went out. After some quick tests I figured out the relay went bad. A month later I got a recall notice about it because it was happening to multiple people.

I replaced the bulbs. There is no relay in any of the boxes for this car but based on the diagram I saw online says that the relay is part of the battery fuse so that is what I also replaced.

When you turn the headlamp SWITCH to ON (not AUTO), do all of the other lights (front, rear, interior) turn ON?

The "headlamp low relay" is integrated into the IPDM/er (fuse block to left of battery on fender wall) and, unfortunately, is not serviceable by itself. If you have a multimeter you can go checking for voltage and ground continuity, but unfortunately if the relay is bad, the whole IPDM/er has to be replaced.

Yep, every light turns on except for both lowbeams. I do have a multimeter but im not exactly sure how to go about testing the voltage and continiuity of the low beam relay or fuses.

G37 Factory Manuals
I would recommend you download section EXL (Ex​​​​​terior Lighting) of the factory manual for your car (above link). There you will find the diagnostic protocols listing step-by-step what to check and how. The wiring diagrams for your headlights are also included.

If fuses 56 and 57 are not getting 12V with the headlamp switch turned ON, then likely there is a issue with the IPDM.

As a side note, do you hear any clicking when you flash the hi-beams?

Just tested, high beams work and make a clicking noise. There is continuity on the 56 and 57 fuses but they get no power when headlamps are turned on.

also another thing I just discovered, when testing the connectors for the actual low beams with the multimeter, they both get 12 volts when the headlamoe are turned on.

So, you're getting power, but do you have a ground?

Progress...
With the headlight switch ON (not AUTO), you should have 12V+ at pin 5 at each headlight connector:
https://cimg7.ibsrv.net/gimg/www.myg...7a3609e602.jpg
https://cimg3.ibsrv.net/gimg/www.myg...9538208942.jpg
https://cimg0.ibsrv.net/gimg/www.myg...7c379f3166.jpg
If you are getting a strong 12V reading, then, to Stealthee's point, are you getting a good ground? Pin 3 should read continuity to any solid, bare metal surface of the car.

Was any work done to the car recently?

https://cimg2.ibsrv.net/gimg/www.myg...afa0c870ab.jpg
^
Here is the connector I was testing for power, it connects directly to the ballast.
https://cimg6.ibsrv.net/gimg/www.myg...6c03b2c771.jpg
Is this the connector I should be testing? The diagram seems to show that there are 8 wires but I only see 6.

No work has been done to the car recently.

That is the correct connector. Not all slots are sometimes used (different options, etc.) Here's what you should check:
https://cimg0.ibsrv.net/gimg/www.myg...17e16cc4b1.jpg
12V+: light switch ON
Ground: continuity to frame

https://cimg5.ibsrv.net/gimg/www.myg...79f95a828e.jpg
https://cimg6.ibsrv.net/gimg/www.myg...f05615eda5.jpg
With headlamps turned on. Also pin 3 has continuity with any bare metal so the ground is also good.

Are the readings the same for both sides? 11.88 volts is a little low but should be enough to at least get some life out of the lamps...

Based on those readings your headlights should be on. From here the issue is either the ballast, ignitor, or bulb.

What gets me is that both sides failed at the exact same time...

If it were me, I would run a set of jumper wires straight from the battery to the ballast and see what happens- again, if it were me (in other words, AYOR).

Maybe others will have suggestions...

Other side same deal 11.9v and ground is good. I ordered a ballast to test with and rule out if thats really the issue or not, I'll update with the results if I havent figured it out by then. Every light on the headlight works without issue with exception of the lowbeams.