I learned now the SJB is the controlling factor based on inputs it receives.Thanks for the schematic.

I do have one question however and that is the "control" for each headlamp has it's own transistor controlling output to the lamp . If that transistor is faulty or the control to the transistor is faulty,wouldn't we get other than normal function to the headlamp ? Could the SJB require replacement?

 

Just a thought... the writeup for the operation of DRLs mentions that the transmission gear selector is taken as an input to the DRL algorithm. Is it possible that the SJB puts the headlights in DRL mode when parked with the engine running? Maybe it will go to full voltage when it's in drive?

I'm concerned about your idea for a "voltage regulator". I don't know that a voltage regulator could increase the voltage (and the average that your meter is seeing is only 10.4). You may need to run a relay with an electronic off delay timer (of only a second or so) that will give constant full voltage to the lights (which would then need to be supplied from another source). Or you might be able to put a big capacitor there to hold the voltage at or near peak. Of course if the low beams go to full voltage in drive, you might just need a regulator to stop the relay from buzzing not caring if the headlights dim in park.

hanky:
What you say is correct but the OP had a scope on it and saw the pulsing. It's unlikely that a fault would pulse in a controlled manner.

 

Way ahead of you about the van in gear. I did that when testing. No change in voltage like what I mean is, the same results as when in park.

Here is something... At the left and right headlight low beam plug, the voltage on my volt meter (engine running) is 14.4v. If I connect the left low beam to the relay, the relay will buzz and the voltage drops to 10.4v at the plug. BUT, when I put the volt meter on the right side low beam plug, it read 14.3v. If I switch things around, like connecting the right low beam to the relay, the right side plug voltage reads 10.4v and the left side low beam plug now reads 14.3v. Only the side that gets connected to the relay has the power drop. So I though to myself, "what if I don't use the headlight as a trigger" so if I do not connect the left or right side to the relay, then both plugs read 14.3v with or without the headlights plugged in.

After I wrote my earlier findings i went out and tested (again) using the left park light power wire to the relay. Results (again engine running van in P, R, N or D) 14.4v at park light plug, No buzzing relay, No voltage drop, 14.3 at both headlights, No need of a voltage regulator and the DRL that is integrated in the LED lights, turn off as per the relay when the park lamps are turned on.

Conclusion... I will wire up a pigtail from the left park lamp socket to the relay and Voila! I will do that tomorrow and post my results.

Thanks again!!!

 

Now that you mention it, that's actually better. Using the low beam for the "DRLs off" trigger would have meant that the DRLs came on when on high beam.

The parking lights use a relay which doesn't care about what's connected to it. Perhaps the FETs on the low beam circuit are sensitive to the additional load of the relay or the relay coil (which is an inductive load) messed with the electronics somehow.

 

Could somebody clear up a few questions ?

Where did this van come from? Canada? Are we looking at info for a van manufactured to American standards?
Feel like we are chasing our tail. The diagram presented is straight forward and doesn't appear that complicated ,unless we are working with different info.

The info and pieces, to me , don't seem to fit.

 

After the latest reply from the OP, I don't think the problem is actually related to the DRLs.

The low beam headlights are not powered by a relay in the SJB but rather by a "Field Effect Transistor" (FET). Ford did this so it could be switched on and off rapidly (many times per second). By switching it on and off and having the on and off times differ, the average voltage is what the lamp sees. If the relationship between on and off is varied (modulated) the average voltage will change. This is called "Pulse Width Modulation" (PWM) and is commonly used for small DC motor speed control and incandescent lamp dimmers. This case is not true PWM because Ford set the pulse pattern at a fixed ratio at the factory to turn the low beam lights on at a lower (average) voltage for DRMs.

I think the actual cause of the low voltage the OP saw was not actual pulses from the DRLs but, rather, unexpected pulsing related to the relay coil (either because of the added load or because a relay coil is an inductive load which the system was not designed for.

 

If the relay coil was getting pulsed, that could account for the buzzing he hears. BUT , the controlled effect of the transistor was still controlled by an electronic part within the dotted rectangle shown on the diagram. Just where is that part, and just how is it controlled with the various inputs?
If it is within the SJB, do you think it might need to be replaced?

 

I don't think any of us really knows the full extent of what exactly is involved is the "Control" section (which I believe is within the SJB). The only clues we have is experience and the list of inputs in my post #5 in this thread.

Since the OP said the system works correctly when the relay is not present, I have to believe that the cause is some interaction between the relay coil and the FET itself.

 

OH MAN YOU"RE RIGHT!! I didn't even think of what you just said. So true, even if all worked from the begging, the power to the DRL would have turned on when illuminating the high beams.

Going to stay with the park lamps.

Thank you etinpa!!

 

Hey hanky,

All is good now. The problem is basically solved. I just have to finalize and tidy up the wiring tomorrow and she's back on the road.

This van was built in the US for Canada, so yes it is a Canadian vehicle. You can almost call these vans hybrids, in the sense they are built for both US and Canada pretty much with minor differences like the gauges and speedometer. Two of my other Fords (one being a 2012 van & other a 2014 PIU) were built in the US for the US. The importer I deal with just had to replace the speedo in the van to match Canada specs and register the mileage and of course they just had to get into the programming and switch things over and activate the DRLs and switch standard to metric for some the electronics and then the Federal inspection. You would have never thought they came from the US.