I noticed in the boot fuse/relay box the far right relay is not there but there are wires on that one. Does anyone know if there should be a relay in there or on my model it should be empty ?. I took the relay out from the left off the empty one and put it in the empty slot. The car would start but not run so I put it back and it was fine after that.

 

I just removed the small black wire from the alternator that was held on with a bolt. I believe this may be the exciter wire. I tested the small black wire using a ammeter and connecting it to ground on the car. Got no voltage at all.

 

Mat:
First, I hope you are not using an "Ammeter"! What you want to do is measure VOLTAGE from the exciter wire to ground -which is shown in the diagram to be wu, meaning white with a purple stripe, as I recall. If you use an ammeter, you will short out the circuit!

The black wire is shown in the diagram to be the suppressor ground lead. Assuming the color codes on the diagram are correct for your car (check by process of elimination), then the black wire is just the suppressor ground and should not show any voltage.

So, replace the blown fuse with the correct amperage one, then check the white/ purple wire to ground with a voltmeter, or better yet a 12 volt test lamp to ground. If the fuse blows, find the short circuit by tracing the wires, or if it does not, then chack the excitation lead on the alternator.

Report back and we can follow some logical steps and solve this quickly!

 

Rule of thumb here is measure the battery terminal voltage with engine and ignition off, then start the engine if the voltage is higher then its charging, to put a demand on the alternator turn on your head lights and heated rear screen this should kick the charge circuit into high gear make sure all your measurements are at the battery terminals

good luck

 

All true, moff, but I think it is well established Mat has a charging problem. The trick now is to determine what the problemis and fix it!

 

ok now the basics have been established its unlikely all three alternators are faulty now check the positive battery lead follow it forward making sure all the termination points are tight it terminates at the starter motor with the alternator, make sure the engine is grounded, if the suppressor is the removable type take it off for now, you can jump 12v onto the exciter wire from the termination point. If you have checked all this and a known good alternator there is no reason it should not charge its a simple circuit

 

Thanks for your post. What are termination points and the suppressor ?. I checked all the ground terminals in the engine bay and boot that I could see. I tightened all the bolts and sprayed them with wd40. I noticed that when tightening one of the ground bolts under the bonnet the spanner touched the engine. It sparked badly and wondered if this should do this normally ?.

 

Are you sure that was a ground bolt? There are + connections also. Better take a meter and check the voltage from that bolt to the engine block.

 

That's a good call from RJ "termination points" where the battery positive cable connects to the other circuits usually on an insulated stud or studs in the engine bay but it will end up at the starter solenoid and that is where the alternator connects to the battery, suppressor stops the electrical noise from the alternator interfering with the radio with out this you will get a buzzing on the radio which increases with engine revs, I have had them go faulty and cause all kinds of issues that's why I suggested disconnecting it for now while you get the charging circuit working.

 

MatT:
I have yet to see where you acknowledge even the existence of the smaller exciter wire that connects to the alternator, And you have mentioned "ground bolts" sparking which are almost certainly the high power positive bolts. I suggest you find one of your friends with a little automotive electrical skill and have him over for a cold beverage and let him have a look. From the progression of your posts, I am afraid you are in a little over your head and you might very well burn the car up if you carry on. This Jaguar charging system is pure vanilla with no extra sophistication, so it should be pretty easy to diagnose and resolve your problem with just a little electrical experience.

 

I gave up and just brought a P Reg Jaguar XJ6 4.0 yesterday. I will sell this car hopefully to someone that wants to repair it. It would be a shame to scrap it.

 

I read this as I had the same issue happen to me checked the right hand side fuse description diagramme got to the 5 amp fuse it was blown ...its at the back of the right hand side fuse box there are two 5 amp fuses, one at front of box one at rear... its the rear one says something like IGN something or other, anyways the post helped me out no end ,so I figure as the genny was faulty and just before the thing packed up the fuse blow , and until that 5 amp fuse is replaced you dont get any charge from the genny on a 1996 jaguar xj6 anyways ...