I have a 1999 xjr. I love this car but it seems the 10 years of age is starting to attract the gremlins.

Ok today from work i was driving home and I noticed the battery light came on.I never had this issue it just started tonight but when I am at like 40 mph or more it seems to go away but the moment i stop it says battery not charging could this be a sign of a bad alternator?(would it throw codes btw? any suggestions JF?)

I installed an autocraft silver from advanced auto about a year ago.with 800 something cracking amps
funny I started the car and at idle its fine but the moment i engage it into drive it starts displaying the message...."BATTERY NOT CHARGING"
Please help

 

could It be a voltage regulator? ..from what I am reading the electrical system is shot.Anyhow I am going to go have the battery tested and alternator where I bought the battery originally.(Advanced auto)

 

Okay so the battery is good from what the test says.
They are saying I have charge but the battery is running low meaning a sign of an failing alternator.does this explain the battery light flashing on and off at speeds of 45 or more the light shuts off does that mean the alternator is working temporally ?

 

Sounds like you lost a diiode or two or three. Belt isn't slipping right? It is tough to test on the car as it won't idle past 3k in park. After I found that out someone here said they thought you could shift it to neutral to run a load test at 4k rpms. Get yours rebuilt for $125-200 at a local shop, buy a reman unit from india or china from a parts store for $300ish or buy a reman one from Jaguar for $700ish. It is a PITA to R&R, not hard but just crappy access down there. My local alt/ start guy was amazed by the lack of diodes in the unit from factory. I think he said there were 6 total. He put a board in which took it up to 8 but said if he had a 10 diode board in stock he would have put that in there. Aparently the more diodes the smoother and cooler it runs. Might want to ask about it if you go a local shop route. Now would be a fine time to change belts as well.

Edit: Forgot add check your battery connection/cable under the pass side black cover at the firewall. They also like to corrode if not attended to. Could be a cheap fix. Also, as was stated it could be your voltage regulator. That would be easy to check as they typically fail to regulate and you'll get around 15volts at your parking governor. Not good to drive like this as it will begin to fry things like your battery and computers.

 

well I drove it home tonight and the headlights were flickering and until the last 3 miles it blacked out on me.I know the battery is toast for sure I barley closed my windows and the car was stumbling ..i am sure it was due to lack of voltage.My only concern was why was the battery light coming on and off at high speeds and when I came to a stop it would turn on and stay on till I got up till about 45 miles mph.
My opinion is I think the alternator went and every little weird thing after was due to lack of voltage.
i will try and have it rebuilt seems faster turn around at a local shop is this just as a good as purchasing one?

now question is there a write up on how to remove the alternator I know I should start by removing the intake....now what ?? Can the alternator be reached by lifting the front end? It should only be held by a tension bolt correct??..

 

Jim,
I think this is what I used

https://www.jaguarforums.com/forum/a...p/t-24263.html

I used a harborfreight belt tensioner tool. If you have a breaker bar that would work to. Access sucks on a garage floor. Expect 4-6 hours out and in. If you have a alt shop locally go that route and call them so they can make sure they have the parts in stock. I got mine back in a couple hours.

 

The light goes of at higher engine RPM because the alternator is partially working. With open diodes, it won't develop enough output voltage until the RPM's are up... so the light comes on at low speed, goes off at high.

BTW, Rock Auto has 4 units, all reman, ranging from $180 for a Remy to $225 for a Bosch. I've had a lot of luck with Rock Auto - quick delivery and quality parts.

 

Agreed with rock auto plus you can usually find coupons for them but I have never had good luck with factory reman alts. Everyone I put in failed in fact. They tend to use cheap components and offer the lifetime warranty. On the XJR I don't want to have do it again.

 

well since I was in a rush and strapped for cash I ended up purchasing one from ebay that was salvaged for 60 bucks now I know I am taking a chance but what do you think..It comes in on Weds.

http://cgi.ebay.com/ebaymotors/ws/eB...ht_3765wt_1388

 

At least you'll be well versed at replacing it the second time. LOL JK. Of course with anything you rarely know how long it will last. Before you put it in take it to an advance auto or autozone and ask for a free alternator check. That way you don't remove yours and find this one isn't good. Save the old one and when you get some spare cash have it rebuilt. Good luck doing the r&r.