240 General: New (to me) 1980 Volvo 244

[Othen]

Originally Posted by Othen

The weather was better today and I stopped being such a wuss - and got on with fixing the rear foglamps.

I did a bit of investigation with a multimeter in the boot and found that there was continuity to earth from the back of the nearside multi-connector and that gave 5Ω, which is exactly what I was expecting with both bulbs fitted, if I removed a bulb (either bulb) this rose to 10Ω, again exactly as I had expected and when both were removed I got an open circuit - excellent, a few minutes work had narrowed down where the fault must be.

There was no potential reaching either bulb, so I deduced from the above and my tests at the switch: there must be a discontinuity somewhere between the switch and wherever the single white wire from it split into two white wires. I didn't know where that happened, but there must somewhere be a junction forward of where the loom disappears through the rear bulkhead and behind the switch - so probably somewhere in the dashboard, or perhaps under the carpets.

Being a bit lazy I didn't fancy pulling out the facia and maybe even the dash, or lifting all the carpets and trim to trace the fault, so I decided to just run a new wire (or two actually) from the switch to the two foglamps.

I could see an obvious route following the path of the rear speaker leads on the offside so I pulled out the rear seat and found some suitable cable. I had some 2 core (about 1mm^2 each I should think) flex that would be perfect, half an hour later I'd pulled the cable through, replaced all the carpet, trim and rear seat. I quite like these soldered and heat shrink joints...

... this one at the switch. At the back I split the 2 core and soldered each side just the same...

Happiness is: working rear foglamps:



I don't know how long the foglamps hadn't been working for, the Barge passed the MoT in October, but maybe the tester just saw the tell tale and didn't check the rear (and they do all look quite similar on a 240).

Good morn chaps,

This one is just me thinking aloud.

I was thinking about this foglamps issue. Now, the previous work on the Barge (I suspect by the supplying Volvo dealer when new) to fit the extra gauges, the Volvo MDS radio/cassette (the radiogram) and the dual tow-bar electrics was very professional. I didn't like the use of piggy-back connectors, but back in the day they were as specified by Mr Volvo (another reason for believing the work was carried out by the supplying Volvo dealer). Following on my line of reasoning, this extra blue switch on the dash here:



... has never made sense. It looks like it should be for some front fog lamps, but none are fitted (and it doesn't look like any have been fitted in the past). That gets us to my theory: when the supplying dealer installed all the extras he/she also fitted wiring for front fog lights in case the owner wanted them, but the luminaires themselves were never fitted. Furthermore, the blue switch is wired as a spur from the white wire that is the output from the rear foglamps switch so the front lamps would only work when the rears were energised (and the blue switch activated also). Finally, that if I traced the wiring from the blue switch backwards I would find it connected to the white wire with a piggy back joint - and that connector had cut through the rear foglamps' supply leading to the failure I fixed in the above.

If you are still reading this well done, it is something like a Miss Marple murder mystery. All this seems more than plausible and explains the spurious blue switch as well as the rear fog lamps.

The question is: should I do anything about it? I'd have to remove the central facia (at least), find the connector, fix the break and remove the blue switch (and so find another blank for the auxiliary switches). To complete the job I'd then have to reinstate the wiring I bypassed with my repair (above) so everything worked as it did when it left the supplying dealer's garage 39 years ago. Then put the trim back together without any collateral damage. All this assumes my hypothesis about the blue switch is correct, that I have guessed its purpose and method of installation correctly.

If I did all that the everything would work exactly as it does now, there would be no change whatsoever in function or appearance (except the unnecessary blue switch would disappear).

Should I pursue this? of course not, the risk of collateral damage in taking apart something that works perfectly well would far outweigh any possible gain.

Just my early morn thought experiment (but do feel free to comment).

Bobwalkin time :-)

[Steve 940]

Hi Alan,

Mmmm.... I can appreciate your position, my first reaction would be 'leave well alone' as disturbing aged plastic always seems to end up with 'collateral damage' as you have said.

However, I think from what I've garnered from my last year or so on here, you probably won't be happy with the switch being possibly wired up in not the finest fashion. Perhaps source dash blanks and anything else that might be needed before commencing.

Although probably a job best to leave till the weather warms up, so the dash plastic is not quite so brittle.

Cheers
Steve

[Othen]

Originally Posted by Steve 940

Hi Alan,

Mmmm.... I can appreciate your position, my first reaction would be 'leave well alone' as disturbing aged plastic always seems to end up with 'collateral damage' as you have said.

However, I think from what I've garnered from my last year or so on here, you probably won't be happy with the switch being possibly wired up in not the finest fashion. Perhaps source dash blanks and anything else that might be needed before commencing.

Although probably a job best to leave till the weather warms up, so the dash plastic is not quite so brittle.

Cheers
Steve

Good morn Steve,

You are a very perceptive chap on both counts.

First I think you are right about the risk of collateral damage far outweighing any possible gain.

The second is that I may not be able to stop myself taking something that works perfectly well apart to achieve some infinitesimal improvement. I've done that many times previously. That is a character flaw of mine .

There is a third way: I'm pretty sure I have a few spare switch blanks somewhere in my spares box. I could just pull the blue switch out, tape over the wires and connectors and fit a blank. That would look smart, but the issue would be as above: I'd know what was behind it and might not be able to stop myself fixing it

[Steve 940]

Wonderful Alan, nothing like a bit of 'self analysis' in the morning.😀

Nothing more niggling than knowing something is just not 'right', although I feel your skill set way outweighs mine to get away with no damage, whenever I do a 10 min quick job, I know it will always take hours/days longer, and involve many ££ to rectify.

Bit like an itch.......

Cheers
Steve

[230ina245]

Why not get some front fog lamps and then wire them in using the blue switch.
That way the blue switch would have a function and the car would gain with the fog lights. A win win situation.
Tim

[Moomoo]

Come come, what is life without a little mystery?🤔

[Othen]

Originally Posted by 230ina245

Why not get some front fog lamps and then wire them in using the blue switch.
That way the blue switch would have a function and the car would gain with the fog lights. A win win situation.
Tim

Hi Tim,

On the face of it that is a pretty good idea, there are three issues though:

a. The blue switch will now be dead because I bypassed the white wire to the rear fog lamps to which I believe it is connected yesterday. That isn't a huge problem, but I'd have to take all the steps I'd listed above, repair the wire I think is broken and then reinstate everything the way it was 39 years ago. None of that is all that difficult, but there is a risk of collateral damage, particularly to the 40 year old plastic trim.

b. I have some spare lamps that were left over from a previous project (the RB) that would be suitable, and early on in this project I did mock them up in place:



... at the time the consensus was they didn't really suit the motor car, and the Barge's headlamps were pretty good anyway (even more so now I've fitted LED bulbs). I'm happy to reconsider this as an option (notwithstanding the third issue below).

c. If I'm right then the wiring as installed would power both the rear and front foglamps via the standard Volvo rear fog lamp switch. The rear lamps are 21W each, and the fronts would be say 55W, so a total of 152W, or about 13A. The wire that supplies the switch is only about 1 mm^2, and the fuse protecting it is 8A. The implied task would be to control the front foglamps via a relay like this:



... which is not is any way difficult and would be far safer than having 13A running around the cabin.

I'm certainly not saying this isn't the way to go, just that it needs a little bit of thinking about to make sure all the explicit and implied tasks are covered, and that the risks (mainly collateral damage) are considered and mitigated. I'm pretty sure I have all the bits required to fit front foglamps in the spares shed (except perhaps a 5 pin relay - cost about a fiver), so there wouldn't really be any costs, apart from maybe half a day of my time.

I'm very happy to consider this, what to people think?

Alan

[Othen]

Originally Posted by Steve 940

Wonderful Alan, nothing like a bit of 'self analysis' in the morning.😀

Nothing more niggling than knowing something is just not 'right', although I feel your skill set way outweighs mine to get away with no damage, whenever I do a 10 min quick job, I know it will always take hours/days longer, and involve many ££ to rectify.

Bit like an itch.......

Cheers
Steve

The first rule of owning historic vehicles is that 'all 10 minute jobs will take half a day' Steve - and that rule scales up with the size of the job.

My concern with all my older vehicles is that I may end up with something that is worse afterwards (possibly via some collateral damage) - a bit like doctors of medicine: 'do no harm'.

None of the things I've considered in the above are difficult from an engineering perspective, the cost would be negligible and I have plenty of time. The only consideration is would the outcome be a worthwhile one when balanced with the risks?

[Laird Scooby]

I'd say make use of the front fog switch and fit a pair of front fog lamps Alan.

I would suggest wiring it correctly though, use a 4-pin relay with two integral diodes, one flywheel diode and one blocking diode and take the feed from the dipped beam wire via the fog lamp switch to terminal 86 on the relay and terminal 85 to the main beam wire.

Connect terminal 30 via a fuse to batery +ve and termianl 87 to the fog lamps.

Having a quick look online, it appears that relays with two integral diodes are NLA, you'd have to get a 4-pin relay with an integral flywheel diode and add a blocking diode between the switch and terminal 86 so regardless of switch position, the relay coil would only be energised with dipped beam, the full beam filaments would act as an earth path for the relay coil.
When full beam is selected (and by extension, dipped beam deselected) the blocking diode would be reverse-biased and therefore not conduct, relay coil is de-energised and fog lamps extinguish.

[Othen]

Originally Posted by Laird Scooby

I'd say make use of the front fog switch and fit a pair of front fog lamps Alan.

I would suggest wiring it correctly though, use a 4-pin relay with two integral diodes, one flywheel diode and one blocking diode and take the feed from the dipped beam wire via the fog lamp switch to terminal 86 on the relay and terminal 85 to the main beam wire.

Connect terminal 30 via a fuse to batery +ve and termianl 87 to the fog lamps.

Having a quick look online, it appears that relays with two integral diodes are NLA, you'd have to get a 4-pin relay with an integral flywheel diode and add a blocking diode between the switch and terminal 86 so regardless of switch position, the relay coil would only be energised with dipped beam, the full beam filaments would act as an earth path for the relay coil.
When full beam is selected (and by extension, dipped beam deselected) the blocking diode would be reverse-biased and therefore not conduct, relay coil is de-energised and fog lamps extinguish.

Thank you for that Dave.

That is very clever, but I'm not too much concerned with the minutiae of wiring at this juncture Dave, rather whether the benefits would be worth outweigh the risk in fitting foglamps, or not.