Ram Promaster Forum banner

21 - 31 of 31 Posts

·
Registered
2019 118" Silver
Joined
·
1,095 Posts
Since you're from Canada, I'm thinking you ordered it from a Canadian source. Would you have a link to the exact item you purchased?

I'm considering swapping to LED despite not having any issues with my halogen bulbs. (For me, none have burnt out (though it's early days still, 10,000 Km only) and they're bright enough).

It's more of a preemptive measure as I've read too many stories of bulbs burning out and I don't want to have to deal with something like that when on the road far from home (which is all of my driving).

I too would prefer 5000K.
You could also just carry an extra halogen bulb or two to swap if needed. No fuss, no muss. ;-) My 2019 is approaching 27K miles without a single issue, including bulbs. I feel about the same as you and find the stock headlights are adequate.
 

·
Premium Member
2018 159 High Roof gas, BC, Canada
Joined
·
1,451 Posts
You could also just carry an extra halogen bulb or two to swap if needed. No fuss, no muss. ;-) My 2019 is approaching 27K miles without a single issue, including bulbs. I feel about the same as you and find the stock headlights are adequate.
I did get 2 of some inexpensive but name-brand bulbs (a whopping $6 each and that was CAD) and put them in the glove compartment. I just didn't want to attempt a bulb swap on the road. I've watched some videos but can't remember if a bulb swap is a lot of work or not.
 

·
Registered
2019 118" Silver
Joined
·
1,095 Posts
Yeah, there are several good videos on it. Entails a few screws, clips and bolts so you probably wouldn't want to do it in the rain or at night, otherwise not bad - 10-15 minutes and easy enough for a campground or even a parking lot.
 

·
Registered
2019 159 EXT HR (3500) in WA
Joined
·
1,224 Posts
You just need a Phillips screwdriver, and a 10 mm socket on a long extension, and a ratchet or something to turn it with.

I was so careful on my new van and still ended up breaking some of the clips on the lower trim pieces. But they seem to go in fine even without the clips.
 

·
Registered
2019 159 EXT HR (3500) in WA
Joined
·
1,224 Posts
OK, I ran a wire from the headlight socket into the van and connected it to a voltmeter.

The LED headlights went for maybe a minute then shut off.

The voltage dropped to 0, so it is definitely the van shutting power off, not the LEDs turning themselves off.

First interesting point: I only see 11.5v ~ 12.0v at the headlight connector. System voltage is typically ~14.25v at this same time. This, combined with the many "my headlights burned out" posts from earlier year vans makes me wonder if the computer is reducing the voltage to the headlights. PWM perhaps? I guess I should also take a scope out and see if they are being PWM'd. Maybe I'll stuff the halogen back in and see what the voltage is with a Halogen.

Second interesting point: The longer they are on, the quicker they shut off -- if I keep turning them back on it will get down to maybe 3 seconds. Compare this to maybe a minute starting from nothing.

Third interesting point: It does not appear to happen in the shop. Engine running, revving, or off the headlights stay on. Why would the van act differently in the shop compared to driving? Very odd.

The only case I can imagine where turning off the power to the headlight would be a good approach is when the light is drawing too much current. What could possibly be helped by shutting the power off in any other situation? SMH

So . . . ignoring the interesting bits and taking this problem at face value:



I will try adding a 14-ohm 50-watt resistor at each headlight and see if that fixes the issue.

If it works, I am thinking of mounting the resistor and the LED driver outside the headlight enclosure to keep the heat inside the headlight enclosure minimized. The hope would be to allow the LED to operate at a lower temperature -- even if the difference is small.
 
  • Like
Reactions: Uvan

·
Registered
2019 2500 tall long wheelbase van
Joined
·
95 Posts
OK, I ran a wire from the headlight socket into the van and connected it to a voltmeter.

The LED headlights went for maybe a minute then shut off.

The voltage dropped to 0, so it is definitely the van shutting power off, not the LEDs turning themselves off.

First interesting point: I only see 11.5v ~ 12.0v at the headlight connector. System voltage is typically ~14.25v at this same time. This, combined with the many "my headlights burned out" posts from earlier year vans makes me wonder if the computer is reducing the voltage to the headlights. PWM perhaps? I guess I should also take a scope out and see if they are being PWM'd. Maybe I'll stuff the halogen back in and see what the voltage is with a Halogen.

Second interesting point: The longer they are on, the quicker they shut off -- if I keep turning them back on it will get down to maybe 3 seconds. Compare this to maybe a minute starting from nothing.

Third interesting point: It does not appear to happen in the shop. Engine running, revving, or off the headlights stay on. Why would the van act differently in the shop compared to driving? Very odd.

The only case I can imagine where turning off the power to the headlight would be a good approach is when the light is drawing too much current. What could possibly be helped by shutting the power off in any other situation? SMH

So . . . ignoring the interesting bits and taking this problem at face value:



I will try adding a 14-ohm 50-watt resistor at each headlight and see if that fixes the issue.

If it works, I am thinking of mounting the resistor and the LED driver outside the headlight enclosure to keep the heat inside the headlight enclosure minimized. The hope would be to allow the LED to operate at a lower temperature -- even if the difference is small.
That seems odd that you're having issues. I have replaced my halogen bulbs with that very same LED headlight bulb. I've had no issues. They've been installed for months now. No resistor. Hope you figure it out.
 

·
Registered
2019 159 EXT HR (3500) in WA
Joined
·
1,224 Posts
. . . very same LED headlight bulb. . . .
There is the 10000LM (~ $32) and the 18000LM (~ $60), I think most people get the 10000 Lumen one.

As a side quest, I think I know why older PMs burn out headlight bulbs like crazy and newer PMs seem to have normal headlight bulb lifetime.

My 2019 uses PWM to regulate the headlight power to the equivalent of about 11.75v any time the system voltage goes over ~12.5v:



(Please don't make fun of my crappy battery-powered scope . . if it's good enough, it's good enough.)

Take a look at this video:


In my PM, you can see that when the ignition is switched on that the constant battery voltage is fed to the headlights. When the car is started, as the voltage rises through ~12.5volts, the ProMaster computer starts PWM'ing the power to the headlights. This makes sense, and I think this is RAM addressing all the burnt out headlights with a software patch. Although I would have to stick the scope on an early model that burns headlights to check.

This also solves my mystery of why I could not get the lights to turn off in my shop, even though they would turn off at idle after a long drive. When I was in the shop the battery was low from playing with the lights. When the engine was running the voltage never got above the threshold because it was still charging hard. Once the battery is charged well, the voltage goes above the threshold and starts the PWM.

Fiinally, I also think I might have an explanation of this:

. . . The only case I can imagine where turning off the power to the headlight would be a good approach is when the light is drawing too much current. . . .
Here is what I'm thinking: The Promaster measures current in some near "instantaneous" fashion. With the Halogens, the current is what it is at any particular time - it is a resistor, so the current would look just like the PWM voltage signal.

With the LED, we are not driving the LEDs directly. Instead, we are driving the input to the constant current LED driver, which typically has capacitors. So when the PWM is off, those capacitors will discharge some. When the PWM comes on, there will be a spike in current as the capacitors are asked to charge instantaneously. My guess is that every once in a while the Promsater samples the current just at one of these spikes, sees that the current is too high, and shuts off the lights.

So ideally I hope to be able to find a way to disable the PWM. If not, I'll probably use a series resistor and a parallel capacitor to try to filter out the current spike. Maybe a series inductor and a parallel capacitor. I'll have to play with it or maybe break down and do some math.
 

·
Registered
2019 2500 tall long wheelbase van
Joined
·
95 Posts
There is the 10000LM (~ $32) and the 18000LM (~ $60), I think most people get the 10000 Lumen one.

As a side quest, I think I know why older PMs burn out headlight bulbs like crazy and newer PMs seem to have normal headlight bulb lifetime.

My 2019 uses PWM to regulate the headlight power to the equivalent of about 11.75v any time the system voltage goes over ~12.5v:



(Please don't make fun of my crappy battery-powered scope . . if it's good enough, it's good enough.)

Take a look at this video:


In my PM, you can see that when the ignition is switched on that the constant battery voltage is fed to the headlights. When the car is started, as the voltage rises through ~12.5volts, the ProMaster computer starts PWM'ing the power to the headlights. This makes sense, and I think this is RAM addressing all the burnt out headlights with a software patch. Although I would have to stick the scope on an early model that burns headlights to check.

This also solves my mystery of why I could not get the lights to turn off in my shop, even though they would turn off at idle after a long drive. When I was in the shop the battery was low from playing with the lights. When the engine was running the voltage never got above the threshold because it was still charging hard. Once the battery is charged well, the voltage goes above the threshold and starts the PWM.

Fiinally, I also think I might have an explanation of this:



Here is what I'm thinking: The Promaster measures current in some near "instantaneous" fashion. With the Halogens, the current is what it is at any particular time - it is a resistor, so the current would look just like the PWM voltage signal.

With the LED, we are not driving the LEDs directly. Instead, we are driving the input to the constant current LED driver, which typically has capacitors. So when the PWM is off, those capacitors will discharge some. When the PWM comes on, there will be a spike in current as the capacitors are asked to charge instantaneously. My guess is that every once in a while the Promsater samples the current just at one of these spikes, sees that the current is too high, and shuts off the lights.

So ideally I hope to be able to find a way to disable the PWM. If not, I'll probably use a series resistor and a parallel capacitor to try to filter out the current spike. Maybe a series inductor and a parallel capacitor. I'll have to play with it or maybe break down and do some math.

I have a rear view camera that I use and a rear view mirror. Cars equipped with LED headlights "flicker" because of the way the camera refreshes and the LEDs get pulsed. Looking at the headlights VIA the outside mirrors the LEDs appear to be on steady as a normal headlight bulb would. I believe this confirms your observation of pulsed power from the PWM.
 

·
Premium Member
2018 136 HR Ont.
Joined
·
660 Posts
Discussion Starter · #29 ·
So ideally I hope to be able to find a way to disable the PWM. If not, I'll probably use a series resistor and a parallel capacitor to try to filter out the current spike. Maybe a series inductor and a parallel capacitor. I'll have to play with it or maybe break down and do some math.
Sounds like you figured out exactly what the problem is. I found this info.


Pulse width modulation, PWM, is a technology to reduce the heat value of halogen bulbs, help the bulbs last longer, and save more power while operating. But LED headlights need constant current supplied, not pulse power supplied from this kind of intermittent power supply system. Installing LED headlights into a vehicle with PWM configurations will result in flashing bulbs or bulbs that turn off after a few minutes. In this situation, a PWM module is required. The module’s large capacitance will basically store up power to eliminate the pulse and supply to the LED headlights with a constant current.

 

·
Registered
2019 159 EXT HR (3500) in WA
Joined
·
1,224 Posts
The more I think about this, I'm leaning towards a different approach.

I think I'll use the PWM'd high beam power as a signal to close a relay, and have the relay supply system voltage to the LED driver:

1) The PWM frequency is high enough that the relay should stay closed continuously.

2) Supplying the system voltage to the LED driver (I observe 14+ volts) will consume less power. According to my charts above: About 35 watts to run the LEDs at 14v compared to about 47 watts to run the halogens at 12v.

3)The current in the potentially noisy PWM'd signal will be much less, so system noise should be reduced.

The other and much more elegant option would be to somehow disabled the high-beam PWM through OBDI while leaving the low beam PWM (where I still run halogens) in place. I have an OBDI reader and yellow cable on order so maybe I can break something when that arrives.

@LarryK : are you aware if there's an option to turn off headlight PWM?

My guess is that if that option is available at all it would probably affect both the low beams and the high beam. So perhaps that's not going to be a fruitful approach. I think I am going to probably just run some extra wire and jam in a relay.

Crap. I just realized that the relay approach will very likely show the headlight out warning.
 

·
Registered
2019 159 EXT HR (3500) in WA
Joined
·
1,224 Posts
I needed to finish this up, so I just installed a relay:
  • Relay coil is wired into the left high beam factory socket.
  • Power is grabbed from the front fuse box main stud, through an inline fuse
  • Ground from a handy stud
  • Power is switched with the relay, which is inside the left headlight housing
  • Switched power and ground are fed to the left LED driver
  • Switched power and ground are routed across the engine compartment to the right LED driver
Works great. Oddly there is no "High Beam Out" message even though the left high beam is only driving the relay coil and the right high beam is open.

The 80KHz PWM appears to drive the relay solidly - this is expected, relays are slow.

The LED drivers get 14v system voltage - this should make them a bit more efficient. Certainly better than the "12v" PWM input.
 
  • Like
Reactions: Uvan
21 - 31 of 31 Posts
Top