I'm curious, what is #23 "relay, light signal" (relä, ljussignal) for?



Thanks
Maurice

Thanks. I've already read through that but the military and civilian wiring isn't the same.



I suspect it's for the headlights high beam, as there are relays for low beam and automatic low beam but not obviously for high beam. I guess I can prove this simply by removing it

Maurice

Oh you have a civil one? Didn't notice. Btw. if you ever need 12V temp and fuel gauge: I got some lying around here. Also a civil dashboard.

No, I have the more common 24v military version. However the (English) workshop manual linked here at c303.de is for the 12v civilian version, and this is one of those areas where the civil and military vehicles are quite different

Maurice

Even apart from the military camo-light circuit, the civil/12v is already different for having the key switch on the steering collumn, while military/24v has it on the dash.
(when doing a power-steering conversion with the Danfoss TAD100/160, the civil collumn switch has to go (it can be retrofitted, along with the original steering wheel, but takes quite some more labour & cost))

That said: the mystery you are probably looking at is the 'alternating' *high* beam circuit, having a different modus-operandi for (low beam) lights on, versus off.
When lights are off, the high beam switch/stalk operates as a (momentary) flasher.
When lights are on, the high beam switch/stalk operates as a latching relay.

This can make fault analysis a bit difficult, obviously....;))
(IIRC, the flasher relay can still work, while the latching relay is broken (not all too sure about vice versa))

Alternative/upgrade: find a collumn switch/stalk (Bosch & Co) that offers both modes physically (pull back for momentary/flasher, push/click forward for permanent on (no need for latching relais (which can already be justified by cost-only, being hideously expensive, compared to regular/momentary relais))
(somewhere in my archive, I have a dazzling circuit diagram, showing how to build a latching relais, based only on (several/many) regular relais, but that might be more an advantage of parts compatibility/resources/availability than cost, definitely at the cost of space & simplicity....:))

Not even sure whether this kind of alternating modus-operandi is typical for Volvo, old vs modern, car vs truck, but I have always considered it an ergonomic nightmare, having driven only vehicles with this 'dual-stalk'.
(as in: not being able to do quick & intuitive flashing when the lights are on)
(and also often finding yourself having the high-beams still on, afterwards)

I like the high-/low-beam setup in the TGB. And once you've figured it out, it's plain logic :-)

Zitat von: tegebe am 09.Februar 2022 21:52:35

I like the high-/low-beam setup in the TGB. And once you've figured it out, it's plain logic :-)

No, you can't flash multiple times easily, nor in any controlled frequency....like between minor/slow hazard or imminent/fast-approaching hazard.

Or, on the other side of the spectrum, the briefest possible flash, for courtesy/giving way.

Total nuisance, ergonomic nightmare....loosing/restricting one of the most easiest ways of communicating with other traffic....

Zitat von: WJM am 09.Februar 2022 21:12:29

That said: they mystery you are probably looking at is the 'alternating' *high* beam circuit, having a different modus-operandi for (low beam) lights on, versus off. When lights are off, the high beam switch/stalk operates as a (momentary) flasher. When lights are on, the high beam switch/stalk operates as a latching relay. This can make fault analysis a bit difficult, obviously....;)) (IIRC, the flasher relay can still work, while the latching relay is broken (not all too sure about vice versa))

I believe you're right. I also I think the problem you describe is precisely the one I have at the moment - I have low beam and flash via the "auto low" switch, but don't have high beam via the blue switch.

Zitat von: WJM am 09.Februar 2022 21:12:29

Not even sure whether this kind of alternating modus-operandi is typical for Volvo, old vs modern, car vs truck, but I have always considered it an ergonomic nightmare, having driven only vehicles with this 'dual-stalk'.

I can't speak for Volvo, but I've never driven a vehicle with this arrangement either. In my experience vehicles from the 1970s onwards have the four-direction stalk, vehicles older than that have a floor-mounted switch to change between low and high beam.

Zitat von: tegebe am 09.Februar 2022 21:52:35

I like the high-/low-beam setup in the TGB. And once you've figured it out, it's plain logic :-)

If it was just the blue switch and the stalk, yes. It's simple though a bit clumsy. However with the auto dip switch it becomes a bit of a mess. One control (the stalk) has different behaviour depending on the position of another control (either the blue switch or the auto-dip switch). That's unintuitive.

I do like the feature that you cannot drain the battery by accidentally leaving the headlights on though.

Maurice