SR5 Factory LED DRL Bulb Solution

For anyone who needs this or hates the idea of hot resistors running for hours on end, I wanted to get this into the public domain. This simple wiring diagram consists of a 10ohm 50W resistor and a time delay relay, that solves this issue for good. You can use any old time delay relay that can handle 5 amps or more, but I just used the type that folks use to delay the start the their HID lights in the reverse (NC to NO), because they are weatherproof relays and easy to mount.




Brief summary of the function: Current flows through the normally closed side of the relay and then the resistor unless the bulb is on solid for 10 seconds (which it would never be while blinking) at which point the relay breaks the resistor circuit and the creation of all that heat, until power is cut (i.e turn signal is engaged) where the relay will flip back and allow the resistor to provide the required load until it is cancelled and the DRLs comes back on again for 10 seconds.

Took me quite a lot of noodling to get to this (although the solution is quite simple) so hopefully it will save some of you some time or worry (if that sort of thing concerns you).

 

So to understand this, on an SR with halogen bulbs for turns and DRL, the DRL's will blink every 10 seconds when turn is not active?

 

The DRLs would not blink, the relay simply removes the resistor (required to prevent LED bulb hyper flash) from the circuit after 10 seconds (when we know the function has shifted to DRL) and that circuit stays open until there is a break in supply power, at which point the resistor again becomes part of the circuit keeping the flasher happy until the bulb is turned back to steady on for 10 seconds.

Essentially, on an SR5 that originally came with halogen bulbs and has been converted to LED a resistor is required to provide enough load so that the turn signal flasher does not think the bulb is blown and hyperflash. External resistors are a well tested solution that for those of us who do not have an LED specific flasher option is the best option that is available. Due to a design decision Toyota made however (using turn signals for DRL), in this configuration the resistor are often run for hours on end, which is not ideal. Even if you use the minimum resistor possible (10ohm in the front) it still creates a good amount of heat, which bugged me a lot.