Jaguar Repair: 86 XJ6 Wont Start, fan shroud, volt meter

Question
QUESTION: I have a Series 3 86 XJ6 and today the car decided not to start. When I turn the key I have all lights but no crank. I get maybe a half turn every time I turn the key.  I have done some continuity checks and everything has seemed to be okay.  The one problem I have found is that there is a relay hooked on the fan shroud that blows the fuse.  I obviously have a short but I am not sure that it is causing the car not to start.

ANSWER: Hi Matt,
This can be caused by several things. High resistance in the starter circuit (battery to solenoid to starter motor to engine ground to body ground to battery)
And of course, it can be a bad starter or even a battery.

You need to take a volt meter and start testing. A first simple quick test is to have someone try to start the engine and this time hold the key in the start position for several seconds and at that time check for any heat at the battery cable ends. They should stay cold. Next put the volt meter across the battery posts and have someone turn the key to start and read the battery voltage before the key is turned and while the key is turned. It should read 12.5v or so before and not be below 10v when the starter is engaged. Put the volt meter on a low volt scale DC and have someone try to start the engine and you check for voltage between the negative post of the battery and the engine itself.
You should see less than a half volt. Now check between the positive post and the positive post of the solenoid the same way and you should see less then a halve volt when the starter is engaged.

Another simple test is to turn on the head lights and hit the starter and note if the lights go out. This is a sign of a bad connection or a bad battery.
If none of this shows a cause you may need to have a shop or parts store run a load test on the battery and a amp draw on the starter.
Howard

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QUESTION: I have checked all that you have posted here and everything seems to check out.  I also removed the starter and had it tested at an Autozone which they said it was bad.  I replaced the starter and still have the same issue.  I am having a hard time following the poor wiring diagram in this Haynes manual but I was trying to verify that the short that has happened with that relay on the fan shroud would not affect the starting circuit.  Thank you for all your help!!

Answer
Matt, when your lights dim when you hit the starter and the starter don't turn the engine, that means there is either a very high resistance in the circuit. (pos. post to cable to solenoid to starter to engine ground to neg cable back to battery.) Or the battery is bad or the engine is locked up and can't turn.

"Seems Ok"??? what does that mean? Did you do the voltage drop tests on all the cables? Was the battery load tested? Does any cable end get warm with the key in the start position? Can you move the crankshaft by wrench?

You can not leave stones unturned when searching for a problem.

Howard