Greetings Ya'll,

My wife's 2015 Nissan Versa SV low beam lights quit working first on the passenger side & within 72 hours also the Driver's side.

I'm an HVAC Contractor, & I don't believe in changing parts, without diagnosing the problem first, but in this case, I did go & buy her new & more powerful light bulbs. Instead of immediately remounting the first new bulb in to the housing, I set it down in a safe position, & turned on the low beams, & it didn't work! I then turned on the high beams & both head lights worked. I also took a hard look at the non-working bulb, & saw that both filaments are not burned out/broken, but, I didn't run a Continuity/Ohm test on these bulbs.

I then went to the fuse box located on the engine fire wall, & tested the fuses for the low beams (10 Amp) with my amp probe & these fuses are not blown.

I then studied up a lil', & found that this "IPDM Test" could indicate whether the low beam issue is in the IPDM, or elsewhere, & I intend to do that tomorrow morning, as soon as it quits raining.

Here's My Question,.... If the "IPDM Test" shows that the Low beam Headlights will work, what other Modules/Controls are downstream, in Series, or Series Parallel, of the IPDM & Fusebox, that I can Test, & hopefully fix?

Your headlamp circuits are pretty rudimentary, you can see them here on EXL-34 (your '15 will be pretty much identical to a '14):
https://www.nicoclub.com/service-manual ... %2FEXL.pdf
If you had juice at both of the fuses then the Low Beam Relay is fine, it's upstream from the fuses. If there's also juice at the wires coming out of the IPDM, then all that's left is wiring, bulb connectors, bulbs, or bulb grounds.

Thank You VStar!

I'm skimming thru that PDF now.

Vstar,

Correct me if I am wrong, but per pg EXL-34, ... Battery Voltage should be present at the Hi/Lo beam relay contacts, as well as at & out of the Fuses, and up to the Head lights?

But what is the Relay Coil Voltage from the CPU to the Hi & Low beam relays? 5.6V.?

The relay is internal to the IPDM, so there's no way to access the coil and you can only check the contacts indirectly, by checking voltage at the fuses with the low beams turned on. The fuses in turn feed pins 14 and 16. So if there's juice at 14 and 16 when you switch on the low beams, it means everything at the IPDM is good and the problem is downstream.

I just ran the IPDM Test Vstar, & all of the components functioned, including the Hi & Lo Beam lights.

Could you explain to me how this Test, by passes the normal function of the Hi & Lo beam switch, on the steering column? Does this Test drop out the switches, & perform it via the BCM?

No, you're misunderstanding the system. The IPDM gets its marching orders over the CANbus from the BCM. There's no direct connection between the switches and IPDM. In test mode the IPDM functions autonomously. So if the lights work autonomously, it means the BCM isn't sending a low beam signal under normal conditions. That probably means it isn't getting one from the switch, so the likely culprit is a bad switch.

Could it also mean that the BCM is bad?

Possible but unlikely, unless there are other things in the switch stalks that don't work. The switch is a matrix type, see BCS-9 here for how it works and BCS-10 for how it's wired internally:
https://www.nicoclub.com/service-manual ... %2FBCS.pdf
If the problem was in the BCM or wiring, you'd get a whole row or column of functions that didn't work. If the problem was the CANbus then all the functions would be out (and the car probably wouldn't even start). The only thing that can individually cause the low beams to fail without anything else failing is if the diode or switch contacts for the Headlamp-1 circuit are open inside the switch stalk.

Vstar,

For some reason, when I click on those highlighted links such as BCS-9, all that it has done, is start the process of opening a Tech Manual all over again.

And I've allowed the many Java Codes for this Site, to operate.

Dunno. I just tested both links and they work. Go into the FSM menu for the '14 Versa Sedan and open "Body Control System".

VStar650CL wrote: ↑

Fri Jul 29, 2022 4:09 am

Possible but unlikely, unless there are other things in the switch stalks that don't work. The switch is a matrix type, see BCS-9 here for how it works and BCS-10 for how it's wired internally:
https://www.nicoclub.com/service-manual ... %2FBCS.pdf
If the problem was in the BCM or wiring, you'd get a whole row or column of functions that didn't work. If the problem was the CANbus then all the functions would be out (and the car probably wouldn't even start). The only thing that can individually cause the low beams to fail without anything else failing is if the diode or switch contacts for the Headlamp-1 circuit are open inside the switch stalk.

Vstar Thank You for that link & advice!

Per BCS-9 The Headlamp appears to send Data /low voltage to the BCM via the "Output 3 Signal", & receives Data/low voltage via the "Input 4 Signal", If I am correct.

Since the Fog Lights, Wipers,Washer, "Bright Beam Flash for Passing",& Turn Signals are all working properly, then theoretically the only thing left is the contacts in the switch, for the Bright Beams. But if that is the case,....I'm still trying to wrap my mind around the "IPDM Test" alternatively turning on the Hi & Lo beam headlights.

Did the IPDM power up the lights, down stream from the Switch?

vstar belay my question about the IPDM,... You previously explained that to me Thu Jul 28, 2022 5:51 pm.

Greetings Vstar,

Other than my Amprobe (combo amp & multi meter), are there any other test instruments that I would need to diagnose this light problem, that You would recommend?

Not really. If it was in our shop I'd be using Consult3+ to pick the brain of the BCM to see if it was getting signal, but you can't DIY that. Your voltmeter can tell you if the switch is actually closing by watching the data line to the BCM, you should see a small change in line voltage when you turn the low beam switch on and a change back when you switch it off. Note that the switch has two low beam throws. On most models only one of the two needs to work, but on some they both need to work. So you should check for movement on both the Input 4 and Input 5 data lines. If one of them has no movement then you have a bad switch. The wiring diagram is on BCS-50, but it's a little hard to follow so I'll sort it out for you. The combination switch connector is M28 on BCS-53, Input 4 is pin2 Yellow, Input 5 is pin8 Brown.

Thank You Vstar!

And You deserve a Hefty Pay raise! Well I know that you ain't gettin' paid, but I absolutely do appreciate all of your help.