It's Christmas so I thought I'd like a special treat - & a bit of a diversion/distraction from the routine repairs & mods,

Always loved sequential turn signals & since Audi re-invented them they seem to be everywhere, Now '97 & up XJ's have 2 bulbs each side so hardly sequential, but the same principal could be applied so they flash alternately [in fact one of the early (i.e. pre-LED) aftermarket kits had a 2 bulb version]. However, they were expensive &, it seems, not very reliable.

Now, I'm sure I saw somewhere a way of doing it using 2 switching relays (each side) but didn't think to save the post/article/link ; ring any bells - or can someone work out the connections from 1st principles &tell me?

 

I'm fairly certain that my 1990 has alternating blinkers stock. You could try checking the FSM and see how it's wired but that might be a real chore.

I'm thinking... with daytime running lights or headlights on, if you split the blinker wire off to a 5pin relay and connected the side marker to 87a, whenever the front blinker's circuit closed, the side marker would cut out, giving the impression of an alternating blinker. I'm not sure if this helps you.

Daniel Stern sells a kit: http://www.danielsternlighting.com/t...rkerflash.html

 

Well it's nice to have some sort of response but obviously I wasn't making myself clear. Your '90 only has one blinker (each side) whereas '97's up have 2, which flash together. They also have sidemarkers that are wired between the direction indicator wire & position lights, rather than ground, so they flash off when the blinker flashes - but that's a red herring because export models like mine don't have sidemarkers.

However you are right about using relays, but I think you have to use 2 5-pin relays; I've seen a post somewhere using that set up to make LED's in sidemarkers flash & I think that set-up might do what I want - but I can't find the post (actually, I'm not even sure where to look).

 

My 1990 definitely has two turn signals and they flash in an alternating pattern.

That’s why maybe checking the wiring in the FSM might help.

 

Do they make a 5pin relay which switches between 87 and 87a? I’m trying to wrap my head around how this would work. If the turn signal closes a circuit and the relay does the flashing, then I have the solution with two 5pin relays. Do you know if this is the case?

 

OK I'm in a hotel room driving myself nuts over here. I think what you're going for is this:
(2) 5-pin relays
When the multi-function switch (turn signal) is activated, it supplies power to energize the first relay. The second relay is connected to pin 87a of the first relay and sends power to the second flasher through pin 87a on the second relay. So you're creating a system where once the turn signal is activated, the first relay is latching and unlatching which is causing an opposite reaction in the second relay. When relay 1 is closed, it simultaneously illuminates the first blinker while opening the second relay's pin which the second blinker is connected to. When the first blinker is *not* blinking, the second relay is energized from 12V power before the thermal flasher and closes the circuit for the second flasher.

You're essentially creating an inverse reaction between the two relays which each open and close the circuit for their respective blinkers.

I may not be 100% correct but I think I'm on the right track. Whatcha think?

 

I think what you have (same as my '96) is a parking light/turn signal under each headlight & outboard of both is a vertical sidemarker which, if wired to flash (something I only thought started in '97) will, when the lights are on, flash off when the turn signal flashes on.

 

@UKXJ https://imgur.com/a/0GuBipZ

 

The whole purpose of a switching relay (as opposed to the less common 5-pin ones with twin 87 pins) is that the trigger will switch the current from 87 to 87a. For that to work, i.e. to use the wire to the turn signal as the trigger, you need a supply to the 30 pin that is live when the turn signal's on but, as I understand it, the flasher relay is before the turn signal lever, so that wouldn't work.
I think the answer is 2 5-pin relays that are both connected 87 to 87a but I can't remember & certainly haven't been able to work out, what the other connections are.

 

This is what the FSM says:
With the multi-function lever in its UP or DOWN position, current flows through the normally closed turn signal flasher contact, the turn/hazard switch assembly, the select turn indicator, the front and read bulbs and the side marker bulbs to ground. With the headlamps OFF the turn and side marker lamps go on immediately. They begin to flash when voltage is applied to the flasher causing the contacts to open and close the selected circuit. With the headlamps ON the turn and side marker lamps flash alternately.

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I'm not understanding this. The circuit is normally closed? Wouldn't that mean that the lights would be constantly on?

 

That illustrates what I was describing (although they do appear to be flashing alternately although the lights aren't on) - but '97's & up have an enclosure beneath the headlight with 2, twin filament bulbs & it is those that I want to flash alternately: bit like sequentials, although there's only 2.

 

I'm not surprised, it's very badly worded: Daniel Stern explains it much better (although more technically). What you have to understand is that the sidemarkers have a dual function not by having 2 filaments but by stringing them between the light circuit and the indicator circuit, i.e. they have no ground.

 

So, I missed this when I posted last night.

Now I'm pretty good at using relays to do more than simply switch high powered things on; long ago I discovered using a switching relay backwards, so you could change the supply for a component. Much more recently.I hit on using one relay to change the trigger for another one. Now, e.g., I have foglights that come on when I flash the headlights (in daylight) but don't come with high beams. Why? Fun - & 'cos I can. However, I design these things, literally, on the backs of envelopes, I've never tried to set it on in a narrative - so I very impressed with your efforts.
I think you might be on to something but the problem, as I see it, is that the "12V power before the thermal flasher" is always live. Really I can't get my head round how the indicator switch/stalk/lever both activates the relay & selects which side flashes. Perhaps I need to sort that out before going any further - & no wiring diagram I've seen helps.