Actually, I just figured out what the diodes are doing. In the original configuration terminal C feeds 12V power to the turn signal lights on the dashboard from the relay making them blink. After the dashboard indicator the power continues on and splices in with the power from the turn signal (Terminal 49A). C must be doing the same thing as 49A. when they join the diode only lets power continue on its way (not back meaning there is a correct flow from the gauge rather than two hot supply wires) eventually grounding at the same points as the actual bumper indicator lights outside.

By cutting out the diode line and making it a direct ground you eliminate the complex wiring. Also you account for the EP26 being a ground. I'll bet that if you put a multimeter on the LGN wire (or the C2 terminal ) when the indicator is on you won't get any voltage because it is meant as a ground. I think it is meant to ground all the indicator lights inside and out.

 

Hmmm. Way to early for me to wrap my brain around this. My dash lights don't work either, and looking at the wiring schematic makes me seasick! Perhaps a cup of coffee and a doughnut first and then a studied review again. After all, it's just a Jag, not rocket science - or is it!

 

I don't understand something. If an LED draws less power then adding a resistor makes it draw more power. Might that bring it back to the original bulbs power?

 

Doug

I am not saying that the gauges lighting matches the Tach/Speedo (I have not put in the new style LEDs in the gauges yet).

I am just trying to get my modern GPS speedo,with excellent internal lighting, to better match the Tach. I took off the green hoods on the Tach - with the old LEDs and with standard bulbs it was too dim. Now it more closely matches the Speedo. Jag lighting was always "subdued" for GRACE...

 

I recently purchased this type of LED bulbs for the big screw in sockets, so far installed them only in a 4 smaller gauges in the dash and they are doing a good job lighting them up: For the switches with a small screw in socket installed these:

 

Latest LED wedge bulbs for gauges are too tall - will not fit at all there... need a good choice of a replacement bulb... LED ones in there now have "frosted"
bulbs and are not a good choice.

 

I didn't replace my gauge lights but I did replace the turn signal indicator lights in the Speedo and tach with #45687 from LEDlight.com and they fit perfectly. They are really bright, I can even see them when the sun is shining right on them.

 

Jess, I wanted to tell you that I followed your beautifully detailed instructions and they work perfectly. I got the Novita EP26 flasher at O'Reilly auto parts. $17 with tax and they had it in stock. I feel that tailgaters are less likely to plow into me now that I have super bright LED stop lights and turn signals. The little light bulb out indicator in the speedometer comes on when I push the brake but it is the old incandescent bulb and is dim so it doesn't bother me. If it does I'll just remove the bulb in the indicator light.

BTW, texting while driving is just sort of illegal in Ohio. If you get a ticket for something else while texting the give you a $150 fine added on. If you don't do wreck (or get caught doing anything wrong) you can text all you want. Obviously I don't. You can easily spot the texters weaving around or too fast or too slow. I avoid them like the plague. Anyway, thank you for a great post with clear step by step instructions .

 

You don't say whether the dash indicators are working. Are they?
Can you check that C2 terminal and confirm if power is coming from it when the indicator is turned on?

 

Oh heck! My dash turn signal indicators are not working now. Did some experimentation and the old flasher doesn't like the new LED bulbs and the new flasher doesn't like the dash indicators. I did find a good article on adding resisters to the bulb circuit:

https://forums.vwvortex.com/showthread.php?2375533-Resistance-Of-1156-Bulb
Back in the day when there was a Radio Shack store on every corner it would have been easy. But now it is internet or nothing.

I think I like the idea of wiring the dash indicator lights directly to the exterior bulb circuits. I think the rear circuit would be the easiest since it is a single filament bulb. Anyone know where to find the wires to the rear light circuits in the cabin? I assume there is a big bundle of wires running from up front to the back of the car for all the circuits back there. If I can find it under the dash it should be easy to find the correct turn signal circuits.

 

Here is a heavy duty resister if anyone wants to go that route

https://www.theretrofitsource.com/morimoto-led-load-resistor.html

 

Hi Yellow.

I am interested in this mod and have been following this thread. I haven't done it but I think it can be done with all except the loss of the bulb out indicator. I have been studying the wiring diagram for the indicator lamps and I don't think a resistor has anything to do with it. The diagram you want to look at is 7.1 in the Publication S57 available for download on this (jaguarforms.com) site. One needs to carefully follow the power flow. You will notice something odd about the way the indicator lamps inside on the dash are wired. I think it has to do with the way the Hella relay worked. I believe the original Hella Relay used terminal C as a power source to the dashboard indicators. I believe EP26 does not. In any case, look at the diagram and you will see that there is a diode in each side's line after the indicator light on the dashboard and before a splice that goes out to the actual indicators bulbs on the outside of the car. Interestingly, the way it is set up with the Hella relay is that when you turn on the Turn Signal, say to the right, the power from the right sided wire from the Turn Signal Switch goes to the same line that has the diode ON THE LEFT!. I cannot identify the meaning of the diode symbol because I do not see a diode symbol surrounded by a square anywhere on the interweb, but I think that the power coming from the turn signal breaks the circuit on the left side meaning that the blinker on the right is getting power from Terminal C which must pulse in time with 49A. When you switch that to the C2 there is no corresponding of pulses between 49A and C2 and so no power goes to indicator lights on the dash. Because of the diode placement, there is no power to either dash board light either.

You could test this theory (and I hope you will because you could help alot of people including me) by removing the two Light Green and Brown wires from terminal C2 on the EP26 relay and splicing them with the Light Green and Blue line from terminal 49A. This could be done right at the relay. This would deliver pulses when either turn signal was activated down the Light Green and Brown wire in the same path they would go if they were connected to the Hella relay C terminal. What ought to happen is that when you hit the turn signal BOTH dash lights should flash. If this occurs it would prove the wiring theory here. At that point you just would need to figure out which Light Green and Brown wire went to the left and which went to the right (by removing one and turning on the blinker and seeing which one still flashes). Then you connect the right Light Green and Brown to the Turn signal's Green and White and the left Light Green and Brown to the Turn signal's Green and red. You would need to do this upstream of the diode so I would think to do this very near the turn signal itself.

I cannot be certain of this, but if you look at the diagram it is very hard to figure out how this wiring would work if it doesn't work the way I describe. Also according to the original poster the parts houses tell you to get a relay called the EP34. This relay's Novita diagram shows wiring for the indicators and dash lights wired up exactly the way I am saying. So maybe that is why parts houses say to use the EP34. This would mean that terminal C2 would be unused on your EP26.

I hope you'll give it it try and let everyone know if this works. If it does Perhaps we can figure out a way to bypass the bulb out sensors so that they'll work for the headlights but not the others?

On edit. I've thought of another indestructive way of testing this theory. You could pull the EP26 out of its socket. Jump some copper from the 49 Socket to the 49 Pin (on the EP26), Jump some copper from the 31 Socket to the 31 Pin and Jump the 49A socket to the 49A pin. Then put some copper in the 49 Socket and connect it by alligator clips to the copper running between the 49A Pin and Socket. Same thing as above.

On second edit: I just talked to an electrical engineer friend of mine and he confirmed what I think is going on here. When the Turn signal applies power to the downstream side of the diode and then power comes to the diode from the upsteam side ( the side it is supposed to come from) the diode won't allow current to pass effectively blocking the circuit. This is called "current steering". Which means Hella C terminal is producing power where Novita EP26 C2 is not.

 

PS. I think the resistor route might be the way to get LEDs to work with the old Hella relay rather than your EP26.

 

Hi Muttony. I think your analysis is exactly correct. I have been studying the wiring diagram so much I am seeing it in my sleep. Yes, the resisters would make the old Hella flasher work but they generate a lot of heat. The instructions say it has to be mounted on a flat metal surface (not many of those left in my car). Hidden back under the tail light would be nice place but right next to the gas tank doesn’t sound good. And yes, the Novita EP26 is wired differently than the original. It works great to flash the new exterior LEDs but does not work with the original dash turn signal indicators. The original design was a very complicated set up with the only advantage is that you get some degree of monitoring of the bulb on the dash. It is my opinion that engineers sometimes make things complicated to justify their jobs. If everything was nice and simple and straight forward we wouldn’t need such a large engineering department, would we? Also, if someone is buying a new luxury car for big bucks and is clueless about how to maintain the car they probably appreciate the bulb monitor (if they even know it exists). Do antique Jaguar enthusiasts like us really need bulb monitoring? If you are going for concourse, yes, but a fun everyday car, no.So my solution is to snip the two light green brown (LGN) wires where they go into the flasher and ground them. Then remove the diodes upstream from the dash indicator lights. Then the flasher will send the flashing signal to the turn signal stalk switch to get routed left or right. The flashing signal goes out to the exterior lights and straight down through the appropriate dash indicator bulb. When the flasher is switched on both dash turn signal bulbs will flash. The whole system will then be much simpler and straight forward (like me).Next week I plan to actually execute my plan and I’ll let you know how it works.BTW, since I installed the 1400 lumen LED bulbs in the stop lights the little amber warning light in the speedometer comes on when I push the brake pedal. I am going to just remove the bulb from the indicator for the same reasons given above.Jeff

 

I can't wait to find out your results. If it works I'm going to start thinking about how to bypass those lght out warning switches in the trunk. IIRC the yonly light up when a bulb goes out which either increases or decreases resistance??? Oh I'll leave that for another day

 

BTW, if you do the cutting where you are talking about you'll need to switch the ex-diode controlled line from one bulb to the other because of the way the turn signal indicator sends power to the opposite side when activated. If instead of grounding the upstream you connect the upstream to the right wire in front of the diode everything else works as designed. You're just cutting out the redundant power from te C terminal you don't have anymore. But you could do it your way if you remove the diode and switch the power lines.

 

Ordered the bulbs mentioned by Roger in post #12 above.

All I can say is "thank you thank you thank you".

I now have all six instruments glowing with equal brightness . I had nearly given up hope. The mis-match was very annoying to me.

An oddity of the Series IIIs....not sure about earlier models....is that the tach and speedo take different bulbs. One screw-in, the other 'wedge type'. It was an easy matter, though, to splice-in a screw-in type socket, sourced from my bin of odds-and-ends, to replace the wedge socket.

Cheers
DD

 

Doug

Glad it helped..I replaced my wedge lights in the fold down instrument panel.. the new LED lights barely fit with the green hoods still in place, but give more light.
I am done now with upgrading the lighting and the car is a pleasure to drive at night... can always adjust the lighting by removing covers now...

https://outlook.live.com/mail/inbox/...mTvnf8iWhes%3D

 

Success! LED turn signals and EP26 flasher work with dash turn signal indicator lights. Here are the steps:
1. Disconnect the battery
2. At the socket where the flasher plugs in, find the terminal with two wires coming in together (the other three have single wires). Snip the two wires and fasten them to a good grounding point.
3. Remove the speedometer and tachometer. Follow the turn signal light wires to the harness. The harness is actually a bunch of wires wrapped in gooey electrical tape. Carefully snip away the tape until all the wires are free. Really messy, have some paper towels at the ready so you don’t get the goo on everything.
4. One of the wires from the turn signal indicator light will contain the diode. The diodes are actually a lump in the wire wrapped in more electrical tape (see photo below). Cut out the section with the diode and then splice in longer lengths of wire. About 6 to 9” will work fine.
5. Thread the longer light leads behind the center indicator lights so they come out the other hole. Put everything back together with the right indicator light in the left gauge (tach on my car) and the left indicator light in the other (speedometer on my car).
6. Voila, the dash indicator lights now flash properly.
Notes:
This is an excellent time to upgrade to new LED wedge light bulbs for the turn signal indicator lights. They are so much brighter and easy to see. Note that they are polarity sensitive – if the don’t work just flip the over and then they will.
There is a small stud with a nut right below the fuse panel that is an excellent ground. Just crimp on a ring terminal to the sniped wires from the flasher and ground them right there. I also put an extra uninsulated ring terminal on the stud – makes an excellent spot to ground my test light or multimeter.
Also, I had installed super bright LED bulbs in the brake lights and I was getting the bulb-out indicator light whenever I applied the brake. While I was behind the speedometer I just removed the bulb from the light-out indicator fixture. There is probably a more correct modification to get it to work, but hey, pulling the bulb works for me.


Turn signal dash indicator light diodes

 

JimC64-please add this to the "How to" sticky thread!

And big thanks to all you guinea pigs for sharing your discoveries!