Okay, a little while back I had installed a pair of LED DRL light modules under my bumper to replace the normal DRL circuit. At the beginning I knew the DRL part of the BCM would start going crazy due to the low draw. Recently I had install in parallel two 50W 6 ohm resistors to help with the low draw issue. So far it has not, the BCM trips the relay on and off about 10 times before shutting it off and turning on the service light. If anyone has any advice on this, it would be greatly appreciated.
And no, I am
NOT disabling the DRL system, so don't go there.
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Try putting the two resistors in series with each other, but keep them in parallel with the circuit.
Is this on the 03 listed in your registry? How do you have them wired?
DRL's use the high beam circuit... so you have the high beams activating the LED's as well? Is that why you are opposed to killing the DRLs and running them off, say, the engine run wiring? (There's ways around this... not too hard to do)
John, according to the wiring diagram for the '03 to '05's and I believe '00 to'02 the DRL's are run off the low beams with a .3 ohm resistor after the relay.
As for how I have them wired, they are powered right from the battery with a fuse and the ground in wired straight to the DRL relay, no headlights in the circuit anymore.
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So you have removed the headlights from the DRL relay, and hooked the LEDs to one of the feeds? Can you post a diagram of exactly how you've wired it? I don't know for a fact how the 03+ works, but typically the high beams are run in series, thereby increasing the impedence, and lowering the light output. If the low beams are the DRL in the 03+, I suspect they run the same.
Can you drop it into Paint and mark in another color where you cut and how you wired the LEDs?
Sorry for the delay but here's an edited pic of where I cut and wired in my lights. After going over it recently I think I may know what is my issue. What I think it is, is that with how they are wired, I have a feeling that the reason the BCM clicks the DRL relay on and off is cause when it does, it is not seeing a signal at all that the lights are on. I am figuring I have to wire in a line so the BCM will see a signal. But I don't want the headlight turning on as well so I think I need to put in a diode so no power comes from the headlights into the DRL circuit.
Am I at least on the right track here?
"United by Individuality"
"If life is a joke, why aren't we laughing?"
"Normality depends on one's perception of reality."
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You are correct that the BCM is realizing that the lights aren't on. The reason is that it's not seeing enough of a load on the circuit.
Here's my suggestion. First, get yourself another relay, and hook the trigger to where your LEDs are currently run, so that the LEDs aren't actually powered from the DRL circuit.
Second, headlights have more than 6 ohm impedance when lit, because the electrical characteristics of the filament change with the increased heat. I'm gonna say your BCM is looking for something in the 10+ohm range. You should really try running the 6ohm resistors in series instead of parallel.
This should take care of the BCM issue, but will not have any effect on the LEDs, since they will not be drawing power through the DRL circuit, they will simply be activated by it.
Okay, I see your idea about the second relay and all, but I fail to see the solution to what is more or less the issue, how am I to go about getting the on signal to the BCM without the headlights coming on with the DRL? That was the main point of the install.
"United by Individuality"
"If life is a joke, why aren't we laughing?"
"Normality depends on one's perception of reality."
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That's what the resistor is for. When you took the headlights out of the loop, the LEDs didn't put enough of a load on the circuit for the computer to think the headlights were on (or functioning--same thing happens if a light burns out)...So you need to put more resistance on the circuit. However, the reason for using the second relay is for two reasons:
1. the LEDs will be affected by the resistors even though they are parallel
2. the current will follow the path of least resistance, so even though you put the resistor in place, you have to figure the math of the total resistance of the circuit with all of the paths in parallel. (Hint: the result is far lower than the individual impedence of each path)
Make sense?
Mr. Quick wrote:That's what the resistor is for. When you took the headlights out of the loop, the LEDs didn't put enough of a load on the circuit for the computer to think the headlights were on (or functioning--same thing happens if a light burns out)...So you need to put more resistance on the circuit. However, the reason for using the second relay is for two reasons:
1. the LEDs will be affected by the resistors even though they are parallel
2. the current will follow the path of least resistance, so even though you put the resistor in place, you have to figure the math of the total resistance of the circuit with all of the paths in parallel. (Hint: the result is far lower than the individual impedence of each path)
Make sense?
I appreciate the help you're trying to give, but let's set the resistors aside. I'm not completely inept when it comes to electrical, but I'm no electrician. Below is another modified pic highlighting what the issue. The issue in not whether or not the computer sees enough of a load, but whether or not it can SEE the load, without the headlights coming on at all.
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OK, looking at it again, I realize what the issue is. The point where you cut into the harness doesn't go to the computer, but the back run from the headlights goes to the ground junction that also goes to the computer. What's needed is a relay there which shunts the ground through a resistor from a relay that the computer monitors.
Here's how I would try correcting this issue. Put a relay and the resistors in where I've circled in red. This should make the computer think that the headlights are still in the circuit. This relay would connect the computer back to the headlight circuit when the headlight switch is turned on.
If I still had my 2001, I'd actually try it myself, but I can only offer suggestions at this point.
edit: I just looked at it again, and I left something out...the other output of the relay in the red circle should go to where that output of the computer already hooked into the headlight circuit. Otherwise, you won't get low beams.
Edited 1 time(s). Last edited Monday, December 09, 2013 6:34 AM
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- DRL circuit mod.png (370k)
Your edit in your last post confused me a bit, maybe because I'm still waking up. What I see from the schematic you posted is that it looks close to me, but still not right. I think the resisted ground shunt you are controlling with the added relay is using the wrong contacts. The computer would naturally see the grounded lights when the DRL relay pulls in, but your relay is opposite. It see the ground with the DRL powered down and then breaks it when the DRL kicks in, so long story short, I think the resistor needs to be on the NO contacts, not the NC contacts. Also, might be a good idea to bypass the DRL relay since you are operating a relay in series with it, resistive loads in series is usually a no-no.
Sparkey, I know what you're saying, but I'm looking at the diagram, and the headlights are not grounding through the BCM, it's just seeing a ground through a load when the DRLs are on. I really think that by having a second relay activating to a resisted ground shunt when the DRL circuit is on will fool the computer. It's a weird setup, having a ground junction go through so many connections, but I think that's what the computer is looking for, and you have to get the shunt separated from the low beams in order to keep them from coming on. The second relay is needed to keep the headlights correctly working when the headlight switch is on, though.
You could probably have the second relay activated in parallel with the DRL relay though, instead of series. Just move the wire from where I connected it by the LEDs over to the wire that goes between the relay and the DRL control of the BCM (light gren/black wire)
Edited 1 time(s). Last edited Wednesday, December 11, 2013 5:48 AM
