03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

[budm]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

To really get into real world, you need to find out what is the range of Voltage the processor can work for the headlights to be on, right now you measure 4.2V but it must have the range that it will still turn on the headlights, can it go down to 3V, 3.5, 4V, etc.? You need to know that because you always want to design circuit for the worst case situation.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

I was thinking right along those lines. I know they turn on at dusk, rather than total darkness, so I expect a lower voltage would turn them on. Also, street lights don't cause them to turn off. There seems to be a delay also, at least to turn off. I'd imagine being at the center of the voltage range would be better, since that would give me room for fluctuations. I'll try to figure out the range when I test tomorrow.

[eccerr0r]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

I really wonder how well diode-or of analog signals really works, especially now that the analog signal lost 0.7V... might have to do an analog-or with op amps.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

I really wonder how well diode-or of analog signals really works, especially now that the analog signal lost 0.7V... might have to do an analog-or with op amps.

From my understanding, there's limits to how many you can cascade, but the 3 I need should be fine.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

Did some testing. It turns out that the security control module sends 5v to the sensor. As the sensor is exposed to light, the resistance to ground is reduced and the 5v signal is pulled down. I wasn't able to determine the minimum voltage to turn the lights on, but at this point it is irrelevant. I also confirmed there's a delay for turning the lights on and off. Now, with all that said, I've also realized that I'm going about this entirely the wrong way. What I should be doing is just turning on the headlights directly, and then I don't have to worry about the delay. Not sure why I didn't think of that sooner. Doesn't look like my truck has a headlight relay, aside from the one built into the central security module. The schematic shows them as being turned on directly by the switch. I'll have to figure out how that works. I guess I may need that transistor to turn on a relay, unless I can use a MOSFET instead.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

Actually, I think the schematic is wrong. The wire gauges at the switch are too small to power the headlights directly. There must be a relay.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

I think the schematic is correct. I'll have to figure out how much current is drawn through the switch and go from there.

[budm]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

It has a delay so the headlights will not be turning on/off instantaneously in case the sensor sees the light and dark light and dark... so the head light will not be flashing on and off.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

It has a delay so the headlights will not be turning on/off instantaneously in case the sensor sees the light and dark light and dark... so the head light will not be flashing on and off.

Such as streetlights, going under overpasses, etc.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

The off delay seems like a good idea even for my application, so they don't flash on and off when switching modes. I found this schematic for an automatic headlight switcher online. It didn't mention any delay, but would I be correct in my belief that the RC network connected to pins 6 and 7 function as an off delay? Also, to adapt my wiper control circuit, could I just replace LDR1 with Q1, and eliminate VR1?

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

Like this...

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

Actually, I think Q1 would have to be a PNP, and pins 2 and 6 on the 555 need to be connected so they both go and stay low when the wipers are on, and then go high when off. The other way, pin 6 would never go high and so once triggered, the lights would not turn off.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

Ok, for a 1.5 second delay, I'd need to change R1 and C1 to 47k and 33µf.

[budm]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

But did you hook up the bread board to the car as it was planned to see what it does?

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

But did you hook up the bread board to the car as it was planned to see what it does?

No. Once I realized that the voltage came from the security control module I knew it wasn't going to work. The sunload sensor varies the resistance to ground, which pulls that voltage down.

[budm]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

I would like to know if the output wire from the light sensor is disconnected what the input to the processor will be. It may or may not have pull-up resistor.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

It went to 5v when cut, and the headlights came on after the 30 second delay.

Edit: When I cut the wire, it was 0v at the sensor. The wire coming from the processor had 5v.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

I realize that it could still be done with the sensor by placing the transistor in series. When off, the lights would come on. But, the 30 second on delay makes it impractical. I was thinking the delay was coming from the sensor, but it's actually in the processor.

Below is a much more practical circuit. It will use a relay to connect the 2 switch wires. There's no delay for turning on but there is about a 1 second delay for turning off.

Question: Should I have a base resistor on Q1, or is the current sufficiently limited already by R1 and R3?

[budm]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

If you are going to turn the headlights directly via power relay when the anyone of the wiper switches is grounded then I do not see the reason for the delay circuit.

[lookimback]

Re: 03 Mountaineer Auto headlamps when wipers are on. Does this look correct?

If you are going to turn the headlights directly via power relay when the anyone of the wiper switches is grounded then I do not see the reason for the delay circuit.

I was thinking that as the switch is turned between modes, the lights may flash on and off. Would the relay be slow enough where that wouldn't be an issue?