Sorry... I'm back.
The problem is it's a "time function" - ie, whilst blinking, the parker/DRL has to be held off.
That means that the "circuit" is still "on" in between the +12V blinker flashes.
Hence a hold circuit for about 1 second (assuming the usual 85 cpm (cycles/flashes per minute) which means that after the LAST flash, the side lamps will be held off for whatever the delay is before being re-powered by the parker or DRL etc circuit.
IMO that is quite okay, and in some ways "cool".
IMO the only practical or legal objection could be that a side gives an extra "off before on" which could be confusing if indicators are immediately changed to the other side. But I'd argue that from the front or rear, that side's main indicators won't, and from the side, it just means an extra (half) cycle which IMO errs on the side of safety/caution if anything.
So, in lieu of a diagram [POST EDIT - see below], per side needs an SPDT relay, a diode and a cap to provide the delay. A small cap if a transistor or FET is used...
The SPDT (changeover) relay is wired with
output #30 to the side lamp +12V.
The normally closed
input 87a is from the normal parker +12V (or DRLs etc).
The normally open
input 87 is from the flasher signal to the main (front or rear) flasher lights.
Hence
normally the parker etc signal powers the side lamps.
When our "delay circuit" energises the relay, it switches over so the side lamp(s) are lit by the flasher can.
Cool?
So, now the delay circuit.
Both methods below are "triggered" from the respective flasher circuit (ie, main flasher lamp wire) and require a diode to prevent the capacitor discharging thru the main bulbs.
The cap is sized so that the RC
time constant provides the required delay of ~1 second or more. t = RC (though not quite if R is the relay...).
The "brute force" method:
Noting that the 10k resistor is not needed (I don't know why it is there unless it's for damping?).
And where #30 is to the side lamp (ie, "
+12V output to Turning Lamps".
And #87 (labelled "
fused +12V") is from the switched parker (or DRL etc) +12V.
And the unconnected #87a if from the flasher signal - ie, to the left of the left "input" diode.
The other method that uses a much smaller cap, has a more predictable time delay and overcomes relay chatter uses a transistor or MOSFET to turn on the relay.
EG - for a relay coil of about 100R (R = Ohm) resistance, C needs to be at least 10,000uF. I'd suggest a 25V 10,000uF which means an electrolytic which is polar, the volume of a cigarette packet, and not too robust (large, and dries out over time etc).
For a MOSFET, the delay is essentially any combination of R & C (similar to the image above) provided R isn't too high - eg, a 1uF cap with a 1MR resistor or 0.1uF with a 10M-Ohm (much smaller than a 10,000uF cap!).
In both cases the RC is an approximation to the "actual" switch off delay - that depends on the relay or transistor or FET's switch-off voltage. But if not long enough, increase the cap (or increase R) in proportion to the increase required.
Also, a smaller relay with lower coil resistance could be used, but the st'd 30A type automotive relays are attractive for their abundancy and easy connection (spades etc).
Incidentally, the above time-delay is the "add on" method for rear flasher with stop/reverse lights instead if needing to re-plumb flasher can and switch, but I have various arguments against it for
main lighting.