After reading many posts on the Forum, I wanted to upgrade the wiring and relays for the hi/lo headlights. I purchased a commercial harness with two relays, one for hi and one for lo, using 14ga wire through out and 10ga 12v source wire. My plan all along was to do away with the original headlight fuse panel and the original headlight relay. The other circuits on the LH wing (park, signal, cooling fan, cruise control, etc.) would go through a new modern fuse block, if needed.

My first snag is figuring how to provide the two signals (hi and lo beam) to my relays WITHOUT using the old relay. Those two circuits originate from the old relay, not the light/dip switch. The dip lever on the steering column doesn't have the switch/latch, it only signals the old relay to do this switching. I am also in the dark as to how the hi beams will latch without the old relay. Is there any way for my plan to work without using the original headlamp relay?

Thanks for any help.

Dave

 

Power for the low beams actually originates at the headlight switch and goes right through the relay. The input to the relay is the blue wire on post 56. Output to the low beams is the blue/red wire on post 56b. You could use power from either wire to trigger your new low beam relay. This would be a "+" trigger.

The ground provided by the stalk switch could be used to trigger your new high beam relay but, as you have observed, there wont be a latching capability. You have to use a latching relay or rig up a different switch.

Cheers
DD

 

That's what I was looking for, how to get that second signal out there and latch it. Thank you so much Doug, I don't think I've ever heard of a latching relay so I googled it and now I know. I'll get one on order.

Dave

 

You already have one! Your existing headlight relay !

Cheers
DD

 

I re-did all the wiring and relays when upgrading to 7" outer headlamps. I can send you my new wiring diagram if you are interested. I have a full write-up also if you wish it. I upgraded the headlamp fusebox and kept the original latching relay. Now all the hi/low switch does is trigger the new individual headlamp relays, which powers each headlamp. I also incorporated a daytime running light system that has saved me numerous times already.

 

Ian - When I bought my car, the PO had installed two relays in front of the engine compartment. One for low beam and one for high beam. I never had to get into the wiring because I never had a problem. But since I've had to get into most everything else, I suspect that may be in my future at some point. Can you post the wiring diagram you have for my future reference?

 

Attached is the wiring diagram. Works a treat!

 

Thank you both, but I was trying to remove the old relay from the headlight circuit. I can see now that some type of latching relay is needed, I just wanted a more modern version. Thanks for posting your schematic, Ian.

 

There are a lot of newer solid state latching relays. I simply searched for "12V automotive latching relay" and there are a lot to choose from. For example the one in my link below does have latching capabilities and alternating 25A outputs for Low / High beam. You'd still need another relay controlled from the light switch to supply current to the latching relay. Basically, two relays is all you need.
https://www.autoelectricsupplies.co....78/category/36

 

Thanks for the info, Karolis. I have bookmarked it and will save for future.
Dave

 

Not because I intend to mess with the lights in my jaguar, as they work. and when they falter, I have the "fix". roll the fuses...

But, I acquired a fascination with relays decades ago. My car has an extended rack of them across the cowl.

And, wonder on wonder, I clicked on the slick diagram. this machine gave me options,one was to save. I did, it is in my pictures folder.. !!

 

Thanks for steering me to your pictures, Carl. That is quite a line-up of relays, I see your '83 is like mine because you have the ? relay also. I'll have some of those, I think. The placement of your PCM is interesting, does the engine heat bother it? That really keeps it out of the way.

Dave

 

Thanks for the compliment. The steering was purely unintentional.

1. I extended the original Jaguar rack the first time. Only sorta OK. But, not right. I removed it and made one of folded metal. spaced for all relays, including the "?" one. Much more satisfactory. Label method still not the best.. Not likely to change...

2. I took note of the GM statement that the PCM housing was prepared for engine bay heat and moisture. And, I liked it's finned alloy look. A shame to tuck it away in a pocket somewhere. In the Cadillac donor car, in a pocket up front and left in the vicinity of the air box. No such room in the Jaguar bay. Could have "tossed:" the inoperative washer bottle. But, that would just present the issue of where to put it. I had hopes for making it work

3. At least 13 years of driving and the PCM shows no sign of distress. Were I to do it again, I would consider a place along the passenger side wing wall, mebbe…

Sidebar: I ended my 3 month absence from a local Rite Aid. Poorly treated when the jaguar and my old cell phone failed me.
OK !!!! Tested my Consumer Cellullar flip phone. No dead spot as the old ATT cell had there, just when I needed it.

And a nice car guy and a musical history lady, A real barn find. A 58 Ford hard top coupe in gleaming black. Marvelous black paint.. Only the roof was lacking, All mostly red oxide primer. Interior pristine, I missed the ID. I thought it a 57. But, no, the 58 had four lamps up front and a more T bird like hood... Odd, three on the tree and 6 cylinder??? Given him, just "get it outta here"
Too bad, I chose not to drive the Jaguar??? Other elder citizens stopped by to comment.. Twas a pleasure..

Carl..