Headlight relay switch (#1307991) - part needed
 

Hi All,

I looking to upgrade the headlight wiring in my '66 Amazon;

From: Footswitch (which will be remain in situ, no need to remove it)

To: stalk flasher function, using a bistable relay like the 140 relay.

Does anyone have a spare they'd be happy to part with?
Or
Know of a good reasonably priced supply?

Prices appear to be excessive from regular sources (£114!!?)

Alternatively, am think I could use a latch style relay + further relay, in tandem.
However, not as enthusiastic about that option.

Appreciate the help!

Cheers, B.

Well, that is a nasty surprise. The 140 headlight relay is Volvo part number 1307991 and it used to be available directly from Volvo. It was used on the 240 series so it was still in production and available for around $45 US$. Volvo appears to have dropped production and the aftermarket replacements have had a rather steep price increase.

Volvo has not de listed the headlight relay from their parts list so you could try your local dealer; but, I expect it will be on infinite back order. Volvo just hasn't got around to updating the data base.

If you don't want to pay the new price, you could troll the junk yards looking for an early 240 for a salvage relay. The other option as you note is the latching relay controlling an interposing hi/lo switching relay.

If you are handy with electronics, it should be easy to fabricate an electronic bi stable latch and have it control a small PCB mounted relay. The PCB relay would then control two external relays for high and low beam switching which has the advantage of allowing you to switch the headlight current through the relays rather than through the headlight switch. The electronic latch and PCB relay would be less than $15 plus your time and effort (and the separate cost for the high and low beam relays). With careful design, you should be able to package it up in a conventional automotive cube relay package like the attached (a different application using a 1-shot latch).

Car builder solutions sell this for £31

Cheers 142 Guy, really appreciate the reply & advice!

Super idea with the build-your-own bistable relay.
I'm certainly going to add that to the project list, for later down the line.
Could be quite the neat solution!

I may have to go with the latching relay + switch relay, in the interim.

That said... I would much prefer a Volvo issued bistable relay controller.

They seem very robust & I understand were also used for P1800ES overdrive relay too.

Should anyone have a 140 relay not in use, but functional; I'd be keen to hear

Cheers

Just to add to the fun…

The cylindrical alumunium relays from Brookhouse have bottomed out..
— this happens to BOTH relays, to add here..
(2 years old, tops)

When simply removing wired connections to check & refresh if needed.
Bottom / inner contents of relay fell/dropped out
Then
Black wire touched out on red.

Never seen this failure mode before; anyone else?

Was not a form pull on wire or connector, good firm contact but only need a reasonable downward “slide” to disconnect.

Obviously resulted in blown fuse 4
(I stupidly didn’t undo battery, figured the above scenario unfathomable?!)

Headlight Relay seemingly dead. (Front)
No stalk flasher visually nor audibly.

Rear light relay; fine. Save for bottomless issue..

Fuse 4 replaced, of course.

Indicators & all other light functions; A-OK.

No impressed with a £35 relay manufacture failure like the attached.

Anyone know of a good solid OEM-keeping relay?

Cheers

On the original Bosch aluminum can relays, the edge of the can is crimped around the base to hold the relay mounting board in place. If you were careful, you could extract the guts from the can to allow clean-up of the insides. It sort of looks like your replacement relay does not have a complete circumferential crimp / retaining bead for the board allowing it to pull out of the can.

The electricals look to be in good shape so I would be inclined to put a few dabs of epoxy around the inside edge of the can at the retaining tits, push the base back in and let it set up. A few dabs of RTV silicone would also work and potentially allow for future removal; but, you need to find an RTV that does not use acetic acid as the curing agent. The acetic acid released during curing on most RTVs can damage electrical parts.

I am not aware of any reproductions of the aluminum can relays. I have rehabilitated the original aluminum can relays using the following process
- extract the guts from the can
- carefully remove the guts from the phenolic base of the original relay
- find a modern automotive cube relay with the matching contact configuration - pick one with a flat base on the outside. You don't want a relay with the external guides set up for installation in a relay box.
- remove the plastic cover from the cube relay
- the internals of the cube relays are typically small enough to easily fit inside the Bosch cans
- carefully cut slots in the original base to accept the spade terminals on the new cube relay - a Dremel style rotary tool with 1.5mm straight fluted bit does the trick for this
- attach the base of the cube relay to the original base with some adhesive and reassemble
You now have a new old relay

I did have an original base fall apart while disassembling the relay. A trip to an electronics supplier yielded a piece of blank circuit board for a replacement. A bit of a hassle cutting a nice round correctly sized piece for the replacement and the board was green so it wasn't a perfect match

Terrific! Thanks 142Guy

I was thinking of using some Durite/Bosch relays and ‘rehousing’ them into an original rectangular headlight relay config; but thought I was being OTP!

Your process makes good sense & I think replicating that to retain the factory look but with repurposed components is ideal here.

I’m actually looking at upgrading to stalk control anyway (allow the old foot switch a breather).

Have found the attached, which if not fully functional component wise; I at least have the right shell to accommodate latch relay and further relay for tandem “140” relay upgrade. …without the £114 plus price absurdity.

Do you think that approach would be worthwhile?

BLS;

Good info from 142Guy as always, but now that you've found the correct SWF relay, why not clean it up externally, check and refurbish it internally, and put it back into service?

See also: http://www.sw-em.com/Headlight_Notes..._Control_Relay

Cheers

I agree with Ron.

Carefully pry open the can to have a look at the internals. As long as the coil has not shorted or gone open circuit it may be possible to rehabilitate the relay. The mechanical linkage that creates the latch function can become non operational due to dust and corrosion. The head light relay on my 142 was 'parked' for about 24 years. It was initially non operational; but, after disassembly, internal cleaning, rehabilitation of the contacts and a little lubrication of the mechanical bits it resumed operation.

I have eased the load on the relay. The relay no longer powers the headlights directly. The high and low outputs of the relay control external high and low beam relays which are fused and supplied directly off the main 12v distribution block. The latching relay (and the headlight switch ) only switches the 50 mA coil currents. The side benefit to this is that the voltages inside the car are higher because the 140 only had a single main feed for both switched and unswitched power in the car.

Cheers Ron and 142Guy!

You know you’re both spot on.
Terrific idea to refurb the SWF relay I found & have now ordered/purchased.
I honestly wasn’t sure that would be viable / if I’d be a viable refurbish-er of the switch.
Worth a go!

Appreciate the SW-EM link as always Ron, cheers.
Shall digest and get to work once SWF relay arrives.

Likewise 142Guy, super helpful advice.

Cheers both!!
BLS