I actually tried three different alternators and the system will not charge. Took the alternators in and they’re fine. Battery is 100% no issues. Not sure where to go from here. Can I get a little help. This is for 1997 jaguar XJ6.

so the problem started when I pulled out of my driveway was down around 10 V. I drove around thinking that the battery just needed to be charged got somewhere turned around, drove back and then everything started dying and it went straight 0 volts The car died. When the car is running I’m getting like 11V. The only thing that happened to it is it sat for a long time without being charged. However, it worked fine for a couple days and then it just crapped out.

here is what ChatGPT saysOn a 1997 Jaguar XJ6 (X300), the alternator does not have a traditional fuse, but it is protected by a fusible link in the wiring harness, typically located near the battery or in the main power distribution area.



Here’s where to check:

1.

Main Fusible Link (Charging System)

• This is usually a heavy-gauge wire integrated into the harness near the positive battery terminal.
• Look for a thick wire (often brown or brown/yellow) running from the alternator to the battery or starter relay.
• There may be a fusible link segment (a short section of wire that looks slightly different or has a rubbery sleeve).
• If it’s blown, you’ll get minimal or no charging voltage even though the alternator is working.

2.

Underhood Fuse Box (Engine Compartment)

• Check the main engine fuse box (driver’s side near firewall).
• Look for large amperage fuses:
  • Fuse #6 (60A) or Fuse #7 (80A) — these sometimes support charging circuits or the ignition supply to the alternator field.
• 3.

Battery Junction Box / Relay Block

In some models, there’s a starter relay or charging system relay near the battery that also routes alternator output.

• Loose or corroded connections here can mimic a blown fuse or dead alternator.

What to Do:

• Use a multimeter to test continuity in the large wire from the alternator to the battery.
• If there’s no continuity, the fusible link is likely blown.
• If you suspect the fusible link, it must be replaced with the correct gauge and rating — it’s not a typical plug-in fuse.

 

Never seen a repair shop with a sign saying powered by AI , just doesn't work with a mechanic's knowledge

This wouldn't work either , but.....................................

A fully charged battery is 12.75 volts so on a turning alternator the positive battery post should normely read higher than that hence charging

A good alternator will read 13.5 to 14.5 volts at the big B + post on the alternator

The loss between alt and pattery is the 3 or 4 terminal connections on the heavy battery cable with every thing off like cabin blowers and headlights and much you can

A test point you can easily check ( turning alternator ) is the terminal post on the right finder engine compartment side very close to the firewall , this cable serves as the starter cable from rear battery and has a tie point at the starter ( upper starter solinoid post ) and the tie in cable continues fwd to the alternator B + post as it pumps higher voltage power back to rest of car including the battery

Pics coming ( made by someone else ) for the starter solenoid tie point that some have found loose nut

 

HMMMMMM, We did change the starter. Could that be the problem? Is there something there that got disconnected or not hooked up properly. I started the car afterwards, but did not drive it because I had to return the hood to get it repainted. The first time I drove it was when I noticed it was not charging.

Parkewr you may have fix my crap again.

 

By the way if you are not using chatgbt or something similar you will be amazed at what it can fix. I have already chased down other issues on this car and others.

 

i had issues recently where i was not getting full voltage to battery.

i managed to diagnose and test that my alternator was infact giving 14.5v however my battery was getting at times under 13v.
I went through and upgraded ground straps, cleaned firewall connections.
eventually tested with multimeter and found the voltage was lost between starter and firewall.

so i disconnected the alt from the starter, cleaned all the surfaces, put it back on nice and tight and now have good full voltage.

 

Double nuting the tie point would not be a bad idea if enough threads , 13 mm nut

brass so shouldn't over torque it

Remember the valve cover is not a good ground for your meter , electrically isolated by plastic top hat bushings on the 13 valve cover mount bolts

You can get on the solenoid terminal post 13 mm nuts with a 3 inch ratchet extension only from under , no need to check lower pigtail terminal post nut unless underperforming starter but wouldn't hurt

The meter test at the starter and to the true rear engine firewall " plain " 2 left and right terminal post can be tricky to visualize as the alternator higher voltage must first travel back ( its own 3rd terminal post cable from right fender to under the right door tunnel / sill chrome plate ) ( this 3rd fender terminal post can give problems as loose or grounding to frame isolators deteriorated ) to under the rear seat pan mega fuse terminal post and then on the fuse other terminal post go back fwd to the rear seat heelboard fuse boxes and the true rear engine firewall " plain " 2 left and right terminal post

 

Hi Phil,

In addition to the brown cable from the battery to the starter, there is a black cable from the starter to the alternator (generator on the schematic). Both cables attach to the same post at the starter. If the alternator cable was not reconnected to the new starter, the battery will receive no voltage from the alternator. I've edited the schematic below so it's easier to follow the cable from the battery to the starter and from the starter to the generator (alternator):




Cheers,

Don

 

Don's pic did not come all the way through

Your 3rd terminal post on the right fender on it's way back to the mega fuses is the dot on the very top line

Your starter solenoid tie point is on the starter block symbel

You will see Don's mention of the at the starter mounted solenoid tie point Brown color ( N ) back to the battery and Black color ( B ) fwd to the alternator

This pic drawn for the slightly different V - 12 starter / alternator / battery main heavy thick cable circuit ( no on the transmission body position rotary switch )

Thanks Watto700 on the pic of the under rear seat pan mega fuse tie point / nut and the recent mention of the starter cable from under the door sill to the right finder quarter panel the right quarter seam terminal post between the 2 not in wiring guide but there ( not the engine compartment right finder 3rd terminal post ) , not gotten to myself on mine , had to shove in garage against close side wall for the judge who want's it disposed since I'm on paper 100 % disabled and my brother can do it " while I'm not looking " That's another WOW story

 

i went as far as installing voltmeters under bonnet to see so no multimeter required here.
one is just on positive on fuse box to ground stud to see overall car voltage.
one connects direct to alt b+ and to ground stud to show direct alternator voltage.
can easy see then if there is any kind of significant voltage loss.

when i noticed i was getting 14.5v at alt but only 13.5v at firewall it helped narrow down the problem

 

All Good. My helper, for my starter replacement, did not hook up the power cable to the alternator...OOOPS