To save time, I’ll start with the current setup on this car which is negative ground. I had an electrical specialist who worked on Jaguars in various independent shops go through my electrical wiring several years ago when I encountered troubles with my turn signals. He went though all wiring and installed a 550 flasher unit. Today on the way home from a drive the turn signals stopped flashing with the indicator light lit up solid. The right front turn signal light bulb appeared less bright than the left so at first I thought perhaps the bulb had burned out. Then I remembered that in the glove box (factory installed) there is a switch for a four way ‘hazard’ flasher. When I tried that all four signal lamps flashed brightly. So then I figured perhaps the (used) 550 flasher unit the mechanic installed several years ago had finally failed. For all I know that used unit may be more than 50 years old so I cannot really complain. I opened up the center of the dashboard to access the used 550 unit. Itwas covered with so much electrical tape that once I got all the tape off I wasn’t sure I had reconnected the wires properly just to ‘hold the place’ until the new 550 flasher will arrive. Attached please find photos of where I think the wires should be. Please share your thoughts on this. Thanks.
Mel R
At least this attachments points to the 550 flasher being the defective component. I ordered a new 550 flasher unit which should arrive in a few days. The question now is which wires to connect to which posts. I think the black wire goes on the horizontal post but I’m not certain. Thanks
I don’t have flasher unit in my hands at a moment but I assume posts are marked P B L. According to schematics, Green wire to B, Light Green with Purple stripe to P and Light Green with Brown stripe to L.
Maybe your wires are discolored, check your Black wire further down to see if it is actually Green.
Thank you KopiK. If you look closely at the photo you are correct that the black wire further up does in fact appear to be green. The 550 flasher I ordered is a brand I think called CRG. Will the terminals on this one also possibly have the letters P B and L on it? If so according to your color descriptions of the wires I stand a good chance of connecting them to the correct terminals which would be a welcome relief. Thanks again.
Mel R
New 550 flasher unit arrived yesterday. It does have the terminals P and L clearly marked, but the B terminal is marked X. Looking at the wires on the old unit, it seems the light green with the purple stripe would go to terminal L and the light green with the brown stripe would go to terminal P. The opposite of what the schematics prescribe. Would it be possible that the car had originally rolled off the assembly line as being wired as positive ground? It was later converted to negative ground by a previous owner. I encountered difficulties with turn signals until several years ago when I took the car to a British car electrical specialist who informed me that folks who had worked on the car previously had incorrectly fitted a 552 flasher to it instead of the correct 550. Since the time he installed the 550 unit, everything was working as it should. So I would think he knew what he was doing. He is out of town now for several weeks, and, needless to say I don’t have the patience to await his return. Several days ago the turn signals ceased to function. For curiosity I turned on the factory installed 4 way ‘hazard’ blinkers which do work. When I stepped out of the car and walked around it, I noticed the right front bulb was not as bright as the left one. Looking though my Haynes manual, mention was made of the necessity of checking the bulb filaments. Before proceeding any further, I ordered a package of 21 watts 1156 bulbs. I’ll try replacing the two front bulbs first in the hope it might cure the problem. If not, the next step would be to remove the 550 unit currently in place and substitute the new 550 unit. But I need to be certain I hook up the wires to the correct terminals. Any thoughts and suggestions? Comment would be more than welcome. Thanks.
Mel R.
UPDATE
NEW 550 flasher and 1156 bulbs arrived today…I tried connecting wires to P and L terminals. Good news is after replacing 1156 bulbs and 550 flasher unit turn signals now function BUT the little green indicators on the steering column no longer work. What to do now?
Try measuring voltages. B or X is Battery, should be 12V when ignition is on. L is Load (Lamps), should be alternating 0V or 12V when flashing. P is Pilot, indicator lamps on the steering column, should also be alternating 0V or 12V when flashing. If P at 550 flasher is ok, follow the wires to see where the problem is. Maybe indicators bulbs are bad?
According to schematics, Light Green with Purple goes to P and Light Green with Brown goes to L. It is same with positive ground and negative ground.
What is strange is that with the defective old 550 connected the indicator lamps are illuminated but the flasher does not work.After installing the new flasher, the turn signal works but the indicator lamps do not. I switched the green/brown and green/purple wires from P to L and L to P terminals and result was the same: turn signals and flasher work but indicator lamps do not.
Very strange 
I replaced the indicator lamp bulbs which arrived in yesterday’s mail. Unfortunately still no success. I cannot understand why those items suddenly do not work since I replaced the 550 flasher. With the steering column cover removed so I could access the bulbs,I cleaned the connections . Still no luck. For now I’ll just live without the indicator bulbs working. I’m grateful at least the turn signals work.
I’m also running out of ideas for your problem.
Do you have possibility to measure voltages? If yes, measure
550 P against ground. When blinkers on, it should vary between 0
and 12-14V at the rhythm of blinkers. If it doesn’t, 550 is broke or wrong.
If it does, problem is somewhere between 550 and indicator bulbs.
If you have no possibility to measure voltages, one way is to buy yet
another 550 and hope it is better.
Maybe others have better ideas, @Mike_Eck ?
I cannot get to the car today. Meanwhile, I’ve gone over this problem in my head numerous times in an effort to find a solution. To recap:
Last week when returning home from a drive, turn signal flasher ceased to function when I turned on the right blinker… I stepped out of the car. to investigate further at which time I noted the right front blinker was not burning as brightly as it should. Once home in the garage, I turned on the factory installed ‘hazard 4 way flasher’ from its switch located (from new) in the glove box. All 4 blinkers now flashed with the right front bulb not as bright as it should be. From these results I figured the right front bulb as well as the 550 flasher were both defective and ordered new 1156 bulbs as well as a new 550 flasher. When the new parts arrived several days later I began by installing new 1156 bulbs on both the right front and left front lamps.Then I sat in the driver seat and tried to activate the turn signals. The flasher would not work, but when I activated the turn signal stalk in either direction, lamp and steering column bulbs would illuminate as intended. At this point I figured the old defective 550 was definitely the source of the problem. I disconnected the old defective 550 unit and installed the new one connecting the B P and L wires as I’d been instructed. I turned on the ignition key and immediately heard the sound of the 550 clicking as it’s supposed to but to my disappointment the indicator bulbs on the steering column did not illuminate even though I’d just installed new ‘Hella’ 2 watt replacement bulbs as well. I stepped out of the car to investigate further. To my surprise when I reached in and out of the car to move the turn signal stalk in either direction, turn signal lamps illuminated as they should. So if I wanted to have steering column indicator bulbs illuminate, I could install the old 550 defective unit once again but they would not flash. Or I could keep the setup as it is now and live without the steering column bulbs illuminating. The empirical evidence I just presented leads me to believe perhaps the P terminal on the ‘new’ 550 is defective. Since a new 550 is not a costly item perhaps I’ll order a new one. Does that make sense? Thank you again for your advice .
Mel R
This symptom is often the signs of a poor ground on that lighting fixture. I would trace the ground wire (which is usually black) back to where it is attached in some way to the body. Bullet connectors in the harness are often a source of trouble due to corrosion or even the female sleeve inside breaks apart which is not easily noted.
You might want to update your Jag-Lovers profile with your location and car(s).
New flasher just arrived…You were correct KopiK. The flasher I installed just a week ago was defective right out of the box! All P and L light’s work as soon às I installed the new for one received a few minutes ago thank you for your sage advice
Mel R