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My LH headlight is working intermittently - no high beam, no low beam (though sometimes it works). RH headlight works fine. (This is a Canadian 2001 Maxima equipped with daytime running lights)
I have:
- swapped light bulb
- confirmed fuse is OK (and power is delivered to fuse)
- confirmed relay is OK (I swapped them and checked relay voltages)
- confirmed continuity from DLR to headlamp connector
- confirmed correct voltages being delivered to the DRL module (terminals 1, 3, 4, 5 all show 12v)
I'm seeing weird voltages on the headlight connectors.
Pins are:
[2]
[1][3]
On the LH(driver) side I see:
11v on pin 3
On the RH(pax) side I see:
12v on pin 1
12v on pin 3
(maybe I'm measuring the voltage wrong: should I be measuring voltage from a pin to ground? Yeah, I'm a noob)
It seems like it has to be the DRL module - but I pulled it, and aside from one slightly dodgy solder joint (which is connected fine) it looks ok.
Am I measuring voltage correctly? What else should I be checking?
The DRL modules do all kinds of strange things because of cold solder problems. Unless you are an electronics tech, you may not have accurately checked the solder connections. Use a jewelers lupe or any 8 to 10 power magnifier to look at the solder joints. You should see the solder flow smoothly onto the component wire, If you see a ring around the wire, that's a bad solder.
When you are checking voltage, connect the meter to chassis ground of the negative terminal of the battery.
The DRL modules do all kinds of strange things because of cold solder problems. Unless you are an electronics tech, you may not have accurately checked the solder connections. Use a jewelers lupe or any 8 to 10 power magnifier to look at the solder joints. You should see the solder flow smoothly onto the component wire, If you see a ring around the wire, that's a bad solder.
When you are checking voltage, connect the meter to chassis ground of the negative terminal of the battery.
Using a jewler's loupe is a great idea - that's what I did
I saw continuity between that cold solder joint and other pins on the same rail- so I figured it might be ok. But as you said, I'm not an electronics tech so maybe the continuity is flaky or causing it to not work properly.
I guess I'll invest in a soldering iron (I really should have one anyways) and I'll check the voltage on the incoming pins to the DRL to confirm the problem isn't upstream (smart entrance control unit, or the switch itself).
Thanks for the confirmation about measuring voltages. It's been a long time since I took an electronics class
The way the headlights are wired is that 12 volts is applied to pin 3 of the headlight connector. Inside the light bulb, the 12 volts is then split to the low and high beam filaments. To turn on the light, the DRL module connects the other side of the lamp filament to ground.
The 12 volt supply to pin 3 also comes through the DRL module. You had 12 volts on pin 3, so this particular line is probably OK.
The other 2 pins on the headlight plug are to light the 2 filaments/beams. Pin 1 is for high beam and pin 2 is for the low beam. When the lamp is not lit, you should measure close to 12 volts. When the beam is on, the pin will measure 1 volt to ground. For the DRL light, pin 1 will measure around 6 volts.
The DRL module has to connect pins 1 and 2 to ground to light up the beam. The DRL module has to be told to do this. So since you swapped the module with another one, it appears the DRL module is not at fault. That leaves the headlight switch itself or wiring. Can you swap the headlight switch?
The DRL module has to connect pins 1 and 2 to ground to light up the beam. The DRL module has to be told to do this. So since you swapped the module with another one, it appears the DRL module is not at fault. That leaves the headlight switch itself or wiring. Can you swap the headlight switch?
Thanks for the details on the pins. That's really helpful. The LH headlight is completely not working now, no longer intermittent.
I'll try swapping them once the weather clears up. Does the switch have two different contacts for each side? One side works fine and that seems like an odd design choice.
How do I remove the combination switch? Is it just a few screws on the panel under the steering wheel to access it?
So I tried to swap the switches, but apparently they changed them between 2001 and 2002 - so that was a no-go.
I did some more testing today and realized my daytime running lights don't work at all!
So here's a summary:
Lights:
Daytime running lights: don't work on either side, in any switch position
High beams: work on passenger side (as flash, or constant on)
Low beams: only work on passenger side (in auto mode at night, or when turned on)
Swapped bulbs, no change
Swapped relays, no change
Swapped (and tested) fuses, no change
Swapped DTRL module with a known working one, no change
So at this point I'm thinking it must be the smart entrance control unit (SECU) or a wiring issue from the SECU to the DTRL module.
Where is the SECU located?
And can someone explain how to read these switch tables from the FSM? They baffle me and I'd like to test the combination switch to rule it out.
The SECU is under the dash between the steering wheel and the center console, essentially above your right leg when you are sitting in the driver's seat.
The service manual has the explanation for how to read the diagrams. It is either at the beginning of the EL or the GI section. I am away from home and can't look it up for you.
Thanks, that is very hepful! (And confusing it isn't in the EL section)
Re-reading the schematics with a better understanding now, I'm leaning towards the issue being either:
SECU internal issue
SECU to switch wiring issue
The pins from the SECU to the combination switch that get ground when the low beams should be on (22, 60) both go to pin 12 on the combination switch. Given that only the RH low beam is working when the lowbeams should be on there is either:
* a break from 22 -> 12, or 60 ->
* or the SECU has an internal issue such that it isn't energizing the relay to provide power to the LH side
TLDR: Everything is good until the dtrl module which is only putting 5-8v to the LH headlight (which does get ground on pin 2). Couldn't find any shorts or resistance from the module to the light harness.
So after reviewing the schematic, it can't be the SECU as the only relation the SECU has to the lights is engaging the relay to send power to the lights.
I pulled the switch and everything tested good on the switch pins. Also confirmed the connectivity between the switch connectors and the DTRL module.
I re-checked the voltages on the light connector and found:
* pin 2 has ground (correct)
* pin 3 only has 5-8v!
So the lamp isn't getting enough voltage7! There's no resistance from the DTRL harness to the bulb harness, the relay and DTRL (pin 5) are both seeing 12v. Bypassing the relay made no difference on the LH side, but does enable the light on the RH side.
So I'm back to thinking that the DTRL is faulty, and my previous test wasn't conclusive as the swap was with a 2002 maxima which has HIDs and possibly a different DTRL part number.
So I retested the daytime light module and confirmed I'm getting wrong/low voltages to the LH side.
To confirm that there wasn't a short or some other resistance on the circuit from the DTLR to the driver's side I 'bypassed' the DTLR by and directly wired some DTLR pins to the LH light and it worked fine.
So it HAS to be the daylight module, right? I know I swapped it with another maxima (2002) - but that max has HIDs and is wired differently. Maybe the daylight module from that 2002 just happens to have the same problem... or maybe I'm losing my mind and didn't really swap them in both directions??
There are a fair number of DTRL problem threads. It seems like a DTRL problem to me based on what I have read, but I have to admit that I have never seen one live or worked on one.
But looking at the wiring diagram, you see that all wires for the head lights come from the DTRL module, both the 12 volts and the ground. So unless you can find a wiring problem, I have to go with a bad DTRL module.
Fixed! It was cold solder/broken solder joint. As mentioned before I did swap the module with one from a 2002 maxima with HIDs and the lights didn't work in my car... And the lights worked in the 2002 with my module. So my best guess is that both modules have the same issue but since the wiring is different with the HIDs it doesn't manifest.
Here are some pictures of some of the broken/cold solder joints for reference
Thanks for this tip. I repaired my control unit succesfully. Each relay has two smaller posts, so four in total. In my case 3 out of 4 were cracked. I resoldered all 4 with good quality solder. Need to be careful to take the box apart. On both long sides there are 2 tabs holding the circuit board in. Fixed my 98 Maxima with 250kkm. It seems the part is discontinued so not easily available.
09-13-2015, 09:59 PM
