240 General: New (to me) 1980 Volvo 244

[Laird Scooby]

It's the rectangular silver jobby Alan, usually a 3-legged animal, sometimes 2-legged and in very rare cases, a 4-legged animal.

For some instrument packs, there's a solid-state alternative which is basically something like an LM7810, 7808, 7809 or similar voltage regulator with a couple of decoupling capcacitors in the right place and a regulated 10, 8 or 9V output respectively.

In short, they drop the battery voltage to a regulated level to avoid the gauges going up and down with battery voltage.

[Othen]

I was just about to pop over to Morrisons to get some gas. The Royal Barge started perfectly, all seemed well, until I turned the lights on... nothing. No dip or main beams. The headlamp flasher still works, so the lamps themselves are okay and all the wiring from the relay onwards must be also. There must be power getting from the distribution bar to the relay (because the headlamp flasher still works). The fog lamps don't work either (they are powered from the rear fogs fuse, which is energised by the light switch).

There are no fuses in the headlamps circuit, the other lights (parking, stops, instruments, interior etc) still work - so the culprit has to be: the light switch - nicht wahr?

Are there any other possibilities apart from the light switch itself failing? It is dark now, and so this will be a job for tomorrow. It seemed odd that the PO had a spare light switch in the spares box (remember, the one I thought was a temperature sender) - perhaps it has happened previously? Do these switches fail often? Is there any way of testing it short of taking the whole thing out? Is removing it a mission in itself?

Any assistance with tomorrows job would be much appreciated.

This is why we love 40 year old cars :-)

[Othen]

Originally Posted by Laird Scooby

It's the rectangular silver jobby Alan, usually a 3-legged animal, sometimes 2-legged and in very rare cases, a 4-legged animal.

For some instrument packs, there's a solid-state alternative which is basically something like an LM7810, 7808, 7809 or similar voltage regulator with a couple of decoupling capcacitors in the right place and a regulated 10, 8 or 9V output respectively.

In short, they drop the battery voltage to a regulated level to avoid the gauges going up and down with battery voltage.

Many thanks Dave.

[Othen]

As sometimes happens, I have started answering my own questions.

I've just had a look at pp26 of the excellent compendium of wiring diagrams Dave sent a while ago. I can see that to test the switch I need to see if there is 12v at pole 56 of the lighting relay, so that will be simple enough tomorrow.

If anyone had any tips on getting the switch out of the dasboard that would be appreciated.

Alan

[Othen]

... continuing to answer my own questions:

I've just tested the spare switch I have (remember, the one that looks just like a temperature sender) and it has normal continuity/discontinuity between pole 30 (power) and 56 (high/low beam) and 58 (parking) - so I think it is healthy. If there is no power at pole 56 of the relay when I test it tomorrow the best thing is probably just to swap out the switch with the spare I have (did the PO know about this issue?).

If anyone can offer advice on getting the light switch out of the dash that would be much appreciated...

:-)

[Laird Scooby]

If memory serves, pull the knob off, undo the collar nut, umplug and remove switch.

Can't remember how to access the switch though Alan, whether from above or below.

HOwever, i'm fairly sure there must be some fuses somewhere for the lights, also are the DRLs coming on with the engine running?

[Othen]

Originally Posted by Laird Scooby

If memory serves, pull the knob off, undo the collar nut, umplug and remove switch.

Can't remember how to access the switch though Alan, whether from above or below.

HOwever, i'm fairly sure there must be some fuses somewhere for the lights, also are the DRLs coming on with the engine running?

Many thanks Dave,

I'm really surprised, but I can't see a fuse involved in the headlamp cct at all (I'd have normally suspected a fuse for a sudden failure like this)... see the cct diagram:



Everything else works (DRL, parking, rears, stops, interior &c), just not the main/dips and the fog lights. The headlamp flasher still works, so the fault must be contained within the circle I've drawn in the bottom right diagram. Further, the live feed to pole 30 of the relay must be okay because the parking lights work. Unless the dementia has set it early, I think the fault can only be with the dashboard switch - by elimination that seems to be the only thing left.

When I get back from Bob's first walk it will be light and I'll test pole 56 at the relay, which should confirm or deny whether there is an output from the switch.

Any other ideas?

Fortunately I have another switch to try (and it seems to check out).

Alan

[Laird Scooby]

Originally Posted by Othen

Many thanks Dave,

I'm really surprised, but I can't see a fuse involved in the headlamp cct at all (I'd have normally suspected a fuse for a sudden failure like this)... see the cct diagram:



Everything else works (DRL, parking, rears, stops, interior &c), just not the main/dips and the fog lights. The headlamp flasher still works, so the fault must be contained within the circle I've drawn in the bottom right diagram. Further, the live feed to pole 30 of the relay must be okay because the parking lights work. Unless the dementia has set it early, I think the fault can only be with the dashboard switch - by elimination that seems to be the only thing left.

When I get back from Bob's first walk it will be light and I'll test pole 56 at the relay, which should confirm or deny whether there is an output from the switch.

Any other ideas?

Fortunately I have another switch to try (and it seems to check out).

Alan

Ditto Alan, i found the diagram again last night, if power was reaching the headlamp relay on terminal 56 then dipped or main beam would work, even if the relay had lost the coil-operated changeover.

That points the finger well and truly at the switch. Gut feeling says it's the switch and it's an intermittent problem so don't be surprised if the lights work this morning!

[Othen]

Originally Posted by Laird Scooby

Ditto Alan, i found the diagram again last night, if power was reaching the headlamp relay on terminal 56 then dipped or main beam would work, even if the relay had lost the coil-operated changeover.

That points the finger well and truly at the switch. Gut feeling says it's the switch and it's an intermittent problem so don't be surprised if the lights work this morning!

Many thanks Dave,

The problem is solved, it was really just 40 year old electrics.

I checked the spade connector at pole 56 of the relay and found it was getting about 10v, I suspected the switch was at fault so I changed it - only a 10 minute job, but recorded here in case it is ever of use to anyone:

The trim drops down to reveal these two self tapping screws:



Then there is just one nut holding the switch on:



The old switch looked as it if had been repaired previously, but seemed to function properly (electrically):



... still no lights, so I returned the the connector at pole 56 of the relay (yellow wire). It was pretty manky, and obviously the reason I'd only seen 10v there when I first tested it. A few minutes with some DP60 and fine emery cloth had the potential difference up to just 12V (which still seemed a bit low considering there is only about 6' of cable run and one switch involved, so I may give it another clean later on).

The lights are working now, dip and main. It was all just down to 40 years wear and tear. It may be that the switch I swapped out contributed a bit as well, bringing the potential at the relay low enough to not operate the lights.

All's well that ends well.

Alan

[Laird Scooby]

The headlight relay (A in the diagram) is a changeover relay so even if it wasn't operating on the coil side of things, you'd still get lights, either dipped or main beam so the fault was the connector on terminal 56 and/or the switch from the sound of things.

When you measured the 12V on term 56, was the engine running or not? Best check is with the engine running, +ve meter probe on battery +ve, use the -ve meter probe around the circuit to find any volt drops.

It could be that after 40 years, the headlight relay is a bit lazy as well and pulling it apart and cleaning the contacts might restore an extra bit of brightness. Alternatively updating it to a modern 5-pin relay should work as well. I can't remember on the 240 if it was the relay or the flash-main/dipped stalk was the latching one so worth checking unless you buy a brand new Volvo relay.