Question about the DRL/hi beam circuit (1 Viewer)

[hankinid]

I'll see your 2 websites and raise you the 2000 LX Factory Wiring Manual...What I posted was a very brief summary from the manual. Check the top of page 89, section 1.

The schematic shows the high beams in parallel via the drl relay, headlamp switch, dimmer switch, and untold other stuff.

You wouldn't add another resistor 'cause you already have the other high beam filament.

I tried disconnecting the drl's based on other threads here...none of the wires I cut on the drl relay could kill it..still need to play with it a little.

Steve

False. They are wired in parallel. There is most likely a resistor somewhere in the circuit that could be below the driver side headlight, in the engine compartment electrical box, or to the left of the steering column under the kick panel. I know that FJs have a resistor in front of the battery. This is where I will start.

Reference these threads:

https://forum.ih8mud.com/100-series-cruisers/43660-drl-question-lc.html


https://forum.ih8mud.com/fj-cruiser/90750-daytime-running-lights-any-options.html

 

[OregonLC]

I tried disconnecting the drl's based on other threads here...none of the wires I cut on the drl relay could kill it..still need to play with it a little.

Steve

Haven't others successfully installed a switch?

 

[SHAGGY101]

Yes, they are in parallel and see 12V. I don't know about the Lexus system but my Hi beams are single filament HIRs. Therefore, there has got to be something (resistor?) that limits the output of the bulb for DRL use.

On another note, I did find a curious relay that I did not see in my FSM. It was where loud describe on the passenger side of the airbox. It seemed to be a "dual" relay. The wire that I saw coming out looked to be the lo beams as well as the hi beams/DRLs.

One thing is for sure that I am totally confused as to why there needs to be so many relays for some lights.

 

[SHAGGY101]

See posts 20 and 32 for disabling DRLs and installing switch.

https://forum.ih8mud.com/100-series-cruisers/43660-drl-question-lc.html

 

[hankinid]

See posts 20 and 32 for disabling DRLs and installing switch.

https://forum.ih8mud.com/100-series-cruisers/43660-drl-question-lc.html

Many thanks...

Steve

 

[pman]

So on the DRL/hi beam circuit on the 100 series, I heard that when the bulb in that spot is acting as a DRL...it is basically working at half power.

Does that mean that the bulb is operating at 6V rather than 12V when in DRL mode? Or does it have something to do with amperage or some other electrical term? Dumb question but thanks in advance

Arent you supposed to be an engineer??? Shoulda gone to GT

this is brilliant! Lol I need to figure out how to use relays but I will give this a try later on this week! Thanks loud!

Relays are stupid simple to use. But I would just trigger it off the existing Hi-beam harness.....it means they will come on when you turn on your hi-beams.....but thats just more light and itll be alot simpler to wire.

 

[1loudLX]

Arent you supposed to be an engineer??? Shoulda gone to GT

 

[SHAGGY101]

Ok, so this is from the EWD that Loud sent me (for an 04 LC).

I will be putting the DRLs on a switch and wiring up some CCFLs to work as running lights. I will post up with a wiring diagram and pics when complete. I just have to wait for some parts to come in. I still have not decided whether to try yo integrate with the factory system or to make my own (I think this option would be easier and less likely to screw up). Thoughts?

 

[SHAGGY101]

Many thanks...

Steve

Let us know if you get it to work.

 

[1loudLX]

but the DRLs on your truck are wired differently, fyi.

 

[SHAGGY101]

Really? By how much? It looks pretty consistent to what I have been able to see on the vehicle.

 

[SHAGGY101]

Here is another thread about disabling DRLs for 03+ vehicles. This method could be used to disable earlier models depending on the difference in wiring.

https://forum.ih8mud.com/100-series-cruisers/164555-drl.html

 

[sonk76]

Ok, so this is from the EWD that Loud sent me (for an 04 LC).

I will be putting the DRLs on a switch and wiring up some CCFLs to work as running lights. I will post up with a wiring diagram and pics when complete. I just have to wait for some parts to come in. I still have not decided whether to try yo integrate with the factory system or to make my own (I think this option would be easier and less likely to screw up). Thoughts?

For what it's worth, it looks to me that this EWD shows that the the high-beams are in fact driven in series anytime the low-beams are off. Only when the low-beams are on, are the two converted to run in parallel.

This would support the DRL mode being achieved by simply running the two high-beam bulps in series. No resistors involved...

In fact, the only resistive elements in the whole second page of the EWD are the light bulps... (did not spend much time looking at the first page, as it is more the control circuity hook ups to the ECU, which still remains a black-box from the EWD perspective.)

 

[FullyLitLED]

Arent you supposed to be an engineer??? Shoulda gone to GT



Relays are stupid simple to use. But I would just trigger it off the existing Hi-beam harness.....it means they will come on when you turn on your hi-beams.....but thats just more light and itll be alot simpler to wire.

I am studying to be a CE! lol what engineering are you doing again?

 

[SHAGGY101]

For what it's worth, it looks to me that this EWD shows that the the high-beams are in fact driven in series anytime the low-beams are off. Only when the low-beams are on, are the two converted to run in parallel.

This would support the DRL mode being achieved by simply running the two high-beam bulps in series. No resistors involved...

In fact, the only resistive elements in the whole second page of the EWD are the light bulps... (did not spend much time looking at the first page, as it is more the control circuity hook ups to the ECU, which still remains a black-box from the EWD perspective.)

Yes, that is what it looked like to me too with all of the relays. There are no obvious resistors in the circuit. However, how do I explain getting 12V on the multimeter?

My only explanation is that there could be some other sort of "black magic" going on in the ECM that we cannot see and that the series of relays at the top of the second picture somehow put it in parallel when combined with the ones at the bottom. I tried to isolate circuits last night to try to find the explanation but no joy.

This wiring diagram is for an 04. I have read that the 03+ vehicles do have different wiring but I do not know by how much.

In the end I am and ME, not a EE and proud of it!

 

[OregonLC]

At what point are you measuring voltage? V1 or Vs?

See Part 7 in the link Resistors in Series - Wikiversity

 

[SHAGGY101]

Right at the bulb (when removed), so V1. The thought was that in DRL mode the output would be 6V and in Hi beam mode it would be 12V. However, when measured at the bulb during DRL mode, the voltage was 12V.

One other thing that sort of negates the idea of series is the fact that the other bulb does not turn off when one side is removed.

Anyone have an 03+ to test?

And yes, according to voltage division, you should see 6V at each resistor or bulb. Which is not the case. If the bulbs are in parallel you should see 12V, which you do.

 

[OregonLC]

Right at the bulb (when removed), so V1.

removed = no resistance = no voltage drop. You were just measuring a single bulb, which would have been 12V.

 

[SHAGGY101]

Regardless of how they work, whether we figure it out or not, I have decided to go the "easy" route to hook up my CCFLs as DRLs.

I will be using a constant 12V source that is powered once the vehicle is on to power the CCFLs. The DRLs will be on a switch as done in previous posts above and the CCFLs will be on a switch too so that I have the option. They will also be hooked to a 5 pin relay so that when the Lo beams turn on they go off. Pretty simple solution so that I do not have to mess with much of the factory wiring harness and most likely less headache in the end.

I will post schematics and some pics once completed. I am just waiting for this switch to get in (it will go to the right of the mirror switch).
This may be a thread hijack but I do not think it needs a new thread. It is also to help give LJ some tips on what to do with relays.

 

[hankinid]

Let us know if you get it to work.

Disconnecting the red with blue stripe wire worked perfectly...double checked high and low beams as well as parking lights...drl's are dead.

thanks again

Steve