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Jaguar Repair/ingnition switch


QUESTION: 1977 xj6L

I understood the final L to indicate low compression engine.
Haynes manual states N.American models compression 9:1 the highest compression.
How do I figure it out?
Thanks in advance Howard.

ANSWER: The XJ-6L referred to the "L" meaning Long wheel base. I believe all  XJ-6 cars sent to the US were all 9 to 1 compression ratio. The only Jags I remember having different compression ratio were the older jags and the ratio was the last number stamped on the cylinder head on the back side of the cam chain area. The last number (sufix) was either a (- 8) or a (- 9)


---------- FOLLOW-UP ----------

QUESTION: Full circle Howard,
Your reply to my original inquiry resulted in replacing the ignition switch with a new one.
The harness connection is a six plug.
The switch I removed a five plug.
The new replacement is a six plug and mated perfectly with the harness.
There is a red and white wire that originates from the gang plug on the wiring from the switch that ends with a female pin connector. This was not on the old switch plug and I can locate no appropriate male pin connector. Any idea what this might be for or might the just be a superceded part and the wire not applicable to my application.
Thank you

Hi David,

I don't have a wiring diagram of the 77 XJ-6 but the Lucas color coding is usually very consistent.

To help ID that extra wire do this.

Note in the wiring of the car harness plug if there is a large 12 gauge white wire with a red tracer or white with a Yellow tracer and if there is, look at the wire in the harness plug of the new switch and see if it too has a heavy white wire w/red or Yellow tracer on it. Also look at the other color codes to see if each color matches the color of the new switch harness. If the colors don't match DON'T plug the new switch in. They gave you the wrong switch. The colors MUST match across the plug connectors.

In the car's harness there is a large white wire with either a red tracer on it or a Yellow tracer and that is the starter solenoid wire on almost every British car made. Do this, look at the car's harness plug and see a large (12 ga) wire colored plain Brown. Take a 12v test light and confirm that that Brown wire is powered (12v).  Now make a short jumper wire of a piece of 12 gauge wire. Plug the test jumper into the plain Brown wire in the car harness plug. (Be careful not to let the end of your test wire touch anything as that is a HOT 12v test lead now.

(Be sure the car is in Neutral or Park if an automatic). Now touch the 12v test wire to the plug of the car harness on the pin that is the White w/Yellow tracer or White w/red tracer and you should hear the starter try to spin the engine. That is a test of the car harness starter circuit only.

Now send me the color codes of the socket of the car's harness. And let me know it the new switch harness colors all match the car harness wiring colors. They must match.
Also, some of the wires are small 14 ga wires and some are large 12 ga wires so you need to tell me which colors of the switch are 12 ga and which are 14 ga.

Let me know


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Howard M. Fitzcharles III


Jaguar from the XK 120 to XJ-6 ser. 3 1987


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

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Import Car magazine

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