1994 Jaguar XJ6 No spark

GAIUS

MEMBER
1994 JAGUAR XJ6
6 CYL
2WD
AUTOMATIC
198,000 MILES

Sometimes my Jag will not start. It turns over, no problem, but there is no spark. I've replaced the plugs, wires, cap, rotor, coil and ignition amplifier, and this morning it acted like it was not going to start, but it did. This afternoon. Nothing. I am at a loss. I cannot see anything else in the electrical system that would affect the spark left to replace.

Tuesday, September 2nd, 2008 AT 9:26 PM

1 Reply

JAMES W.

MECHANIC
2,394 POSTS

The no start condition has to exist for this test.
With key in the run position, with a test light, test the + side of the ign coil for voltage. If no, Check the main relay for in/out voltage. (I use a spare relay with the plastic cap removed so you can physically see if the relay is closing OR you can manually close the relay to pass voltage.) If relay is closed, check the ignition relay. Relays are located under the glove box. The entire time you are testing these relays, you should be the ciol + terminal for voltage. If you have + voltage to the coil but, still no spark, I would suspect the ign amp, which you have changed, the ECU or the Crankshaft position sensor. IF it is the CPS, you should also lose fuel pump and injector pulse. Hope this helps.

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Friday, October 3rd, 2008 AT 2:27 PM