XJ6 & XJ12 Series I, II & III 1968-1992

High beam switch

 
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Old 06-08-2019, 01:54 PM
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Default High beam switch

My headlamps stopped working. Some time ago, I converted my outer headlamps to 7 inch ones and they worked then.
I have never driven my car at night so I don't know when the stopped working.
All fuses and wiring are good.
When I play with the high beam switch the Low Beam headlamps flicker but no High Beam
I can hear the latching mechanism in the headlamp relay working.
At the fuse box I get no power on the High beam circuit which is the Blue/White wires.
I get intermittent power at the fuse box for the Low Beam circuit, which is the Blue/Red wires. This happens when I toggle the High Beam switch.
Is it possible that the High Beam switch is faulty? and is it repairable?
 
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Old 06-08-2019, 03:55 PM
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The high beam switch at the column stalk simply provides a ground to trigger the headlight relay. To eliminate it as a possible problem, remove the blue/black wire from the relay and use a scrap piece of wire to ground that terminal of the relay....which is marked "31B". If the problem goes away then the high beam switch or associated wiring and connectors is suspect. But, since you hear the relay actuating, the high beam switch is probably OK.

The switch itself is merely a little spring metal tab at the base of the stalk. It can be cleaned with aerosol electric contact cleaner if you remove the column shrouds for access.

The nest of bullet connectors under the headlight fuse box can cause problems as well. Cleaning them is never a bad idea. The fuse box can be lifted away for easier access to the connectors by removing one small bolt.....5/16' wrench size as I recall.

The relay itself can be opened up to clean contacts

Dirty fuses cause problems, too. The end caps corroded...as do the little clips the fuses snap into

Check headlight grounds. They're on either side of the radiator, facing forward. Often corroded as they're directly exposed to the weather

Cheers
DD
 
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Old 06-08-2019, 05:34 PM
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Thank you Doug. I will follow your guide and report thereafter.
 
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Old 06-09-2019, 06:36 AM
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I got rid of all front lighting problems when I upgraded to 7" outers. All the switches do now is provide grounds to five separate relays, one for each headlamp and one for the daytime running lights built into the high beam unit. I also upgraded the headlamp fuse-box to one that uses modern plug in fuses, thereby eliminating the pesky tubular units. Now my headlamp switch just controls the relays that have a dedicated power supply from the bulkhead power posts.
 
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Old 06-09-2019, 01:36 PM
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@ IAN: Given that I am having this issue now, I may have to do the modification like you did.
I have most of the items you listed in your post for your conversion. I will check my storage shed tomorrow.
When I did my 7 inch conversion, I went for LED outside headlamps and Amber 5 3/4 for my inners (high beam).
On the 7 inch LED headlamps I have the DRL wired to a microswitch which I installed at the gear shifter, so the DRLs only come 'on' when the gear shifter is in 'D'
 
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Old 06-09-2019, 07:17 PM
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So, after following Doug's instructions, I narrowed down the problem to be the latching mechanism in the relay.
I removed and opened up the relay and the plastic piece that the latching mechanism rides on was melted.
based on what I saw, I believe that it is fixable, in that I can trim the molten plastic off with a sharp blade.
In the mean time, I purchased a 5 terminal latching relay (Standard Products # LR35) from Oriellys, installed it and all headlamps now function as they should.
The only issue I have is that it is a 30 amp relay. I believe it should be a 40 amp relay.
If the OEM relay is not fixable, Welshent has a relay with 6 terminals for $85. Their website states that it is for 79-86 XJ6???????.
Other option would be to use the output from the relay as a trigger for separate relays for each headlamp, pretty much the way Ian in Canada did his.
Thoughts?
 
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Old 06-09-2019, 08:08 PM
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Good work !

Does the LR35 have the latching capability?

Cheers
DD
 
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Old 06-10-2019, 04:07 AM
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Yes. The LR35 (JD 142C-12V) relay has the latching capability. As stated above, pull on the high beam switch and the high beams turn on and stay on. Pull on the high beam switch again and the high beams go off. And yes, you can hear the latching mechanism activate just like the original relay. As per the specs at the store the "L" in the part number is for latching
 

Last edited by sanchez; 06-10-2019 at 04:10 AM. Reason: add info
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Old 06-13-2019, 05:02 AM
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30A at 12W gives 360W which seems adequate for a standard headlight setup.

I did that same LR35 swap a couole of years ago and its still working fine. Glad you got it sorted.

The other thing you could consider is putting in a standard 40A to feed the headlight cct (input to the LR35). The rotary headlight switch would then just operate a relay rather than dragging high currents through a dash switch , which always creeps me out. This made a visible difference to my low beams. I just picked up battery off the firewall post on that side.
 
 
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