Hi guys,
My 1995 Jaguar XJ6 3.2 had a bit of a problem starting (posted about on here a while ago) and was also due an M.O.T. ... This is a Brit safety check which needs to be done every year and tests things such as brakes, emissions, corrosion, light and a lot more. Anyway, the Jag went into the garage and after a few days I got a call from the mechanic. He said that he couldn't find anything that would cause a "Fail" on the M.O.T. but there were some tests that he had been unable to do because they had never been able to run the car long enough for it to get to normal running temp. He said that the problem was a duff alternator which was causing the electrical system to stop charging. My query is that when I started the car previously, the dial on the dash that is supposed to show the charging state of the system would go straight up to half way into the black and stay there.
So how does that work if the alternator is goosed? Can the dial still show such a charging level even though the electrical system is *******?
All I can say for sure is that in the last few days before the car went to the garage I could put a fully charged, heavy duty battery into the car and try to start her. After an initial crank without actually stating, the electrical system seemed to die, with not even the courtesy lights working.
Any ideas?
Cheers,
Steve

 

Something seems wrong there. A good battery should have a lot more life in it than just one start. The last time I had a low battery, (accidentally left the trunk open) even though the car wouldn't turn over, the interior lights would still work. The radio worked to, for a few minutes. Are your battery posts nice and clean? or maybe there is a bad Grounding connection somewhere? hmm.....

 

Hi win, thanks for the reply.
As for the battery posts, they seem to be clean and they have a smear of Vaseline on each one.
Let me explain more about the battery condition to maybe give a clue.
I have 2 batteries. One that came with the car when I bought it and a brand new heavy duty one. I also have a proper battery charger that charges the batteries from the mains. This means that I always have a battery that is fully charged. (If I am at home)
Having put a fully charged battery into the car I could then get in the driver's seat and turn the key in the ignition. All the dash lights would come on and I could then turn the key a bit more and get a very healthy sound of the car trying to start. After maybe 10 seconds of turning over I would turn the key back to "Off". It is at this point that you may notice that the driver's door courtesy light has also gone off. I had left the door open to check for this.
Turning the ignition key again gives no results. No lights on the dash and not a peep from the starter.
OK, this is where it gets interesting.
Opening and closing the boot lid a few times can sometimes cause the boot light to come on at which point the starter works and the car may or may not start.

 

Pretty classic symptom of a dirty earth.
Closing the boot probably shakes the connection up a bit.
I don't know your car layout but follow the negative lead back to where it fixes to the bodywork, remove the bolt and clean everything up.
If that fails check the cables where they attach to the battery post clips.

 

Thank you for that info, Steve.
I remember taking a good look at the neg lead before the car went into the garage and, to me, it looked perfect. In fact, I would say that the previous owner had put all new connections on it and done a thorough job of cleaning it all up in an attempt to cure the problem.

 

Have you got a voltmeter?
If so get the car in the 'dead' state and find where the volts have gone.
Start (obviously) at the battery posts then +ve post to chassis, +ve clip to chassis etc.
Again, I don't know your car but many vehicles take a big fat lead to the starter solenoid and then pick up the 'car' supply from that. This is another place to look and check volts to ground.
It is bound to be something simple....but often damned elusive.

 

Steve ..... Sounds like a plan if only I knew what you meant, lol. No offence intended but you are speaking "Car expert" to a guy who just about knows where the engine lives. I appreciate the time you took to figure out what I needed to do but I guess that is something that I need to pass on to the mechanic, which i WILL do if he is having problems identifying the problem.
As a side issue, the mechanic who is now fixing the car's electrical issues and putting it through the M.O.T. phoned up this morning to say that his supplier of alternators to suit my Jag had just phoned him to say that it would be Tuesday before he could get one to the garage.
Ho Hum.

 

Sorry, didn't mean to blind you with voltmeters!
I guarantee the problem you describe is not due to the alternator though.

 

I agree with Steveinfrance. If I were you, I'd think about looking for someone else to check the problem. can a bad alternator be causing these symptoms? its only real purpose is to keep the battery charged and supply energy to the car to supplement the battery during the cars operation. and if the gauge says at least 12 to 14 volts its probably okay. I think the problem is likely to be a bad ground somewhere. or loose wire... You may want to check the wires at the hinge on the right side of the boot, sometimes they get frayed over time,with opening and closing, and I think I read somewhere that if the boot lights don't have power, the cars security system can be triggered and the car won't start. Just a thought, could be a shot in the dark. good luck, Mike

 

Mmmm, that's cause for thought.
Thank you Steve and Mike.

 

Stevie,
Be brave. Take some red medicine (not too much) or a large G+T.
Do Mike's check - he obviously knows this mark of Jag + I don't.
If that fails you're in Steve's 'MY TRACTOR WON'T START' mode - my wife runs the farm, I'm having a nice zzzz thinking about the Morgan +4 and all those nurses and I get this reality check about 1 morning in 20.
Open the lid - that's the bit at the front where the injun lives.
Find the starter motor - you CAN do it.
Look for a big fat cable going to it.
Is it done up tight?
Waggle every cable + connector round the starter.
If that fixes it I'll give you my PayPal a/c !!!
Alternatively take the Eurostar here and I'll fix it for you.