Hi all:

I have a 99 XK*, which I've owned since July.

My recollection is the volt meter on the dash shows 13 volts steady at all RPMs. In the past two days I see the following on the meter:

• 10-12 volts at idle and up to 1200 RPMs
• 12 -13 volts when driving on city streets
• 13 volts at highway speeds

The lower than expected voltages will be seen more frequently the more auxiliaries I turn on: fan, driving lights, rear window defrosted.

I don't believe this is normal. Do you agree it's not. If something is wrong, would you think its the regulator, alternator or both.

Thanks

Thom

 

Hi Thom,
All normal observations. The voltage may slump at low speed under heavy load, and will recover with a bit more RPM or relief of load.

There are some threads regarding decrease of alternator pulley diameter to wind it up a little faster. But in my mind, everything is normal, you can probably find something else that needs done with your XK8.

Regards,

Jerry

 

Thom - welcome to the forum - as this is your fisrt post, please stop by the new member section and post an intro. In return, you'll receive a warm welcome and useful tips for forum navigation: https://www.jaguarforums.com/forum/n...-intro-must-5/

As for your question - normal even at idle should be around 13. Anything below 11 - you could experience spurious warnings/faults. So - how old is the battery - should be a date code on the top - most batteries can go for 3-5 years, some longer but........

How often do you drive her? When not driving - is she on a battery charger/tender (important if not a daily driver)?

first thing I would do - make sure the battery is fully charged, then see what happens when you start/drive. If questionable - stop by an Advance Auto and have them check the battery and charging system. They can tell you if the battery is going south or if there is a problem with the alternator/charging system

 

Hi Steve and Jerry:

The car is a daily driver putting on 50 miles a day on average. Unfortunately, I don't know how old the battery is. It looks new, but whoever installed it did not punch out the date code. My guess is the seller installed it sometime last Spring, but that's just a guess. My best recollection is the panel volt meter read a steady 13 volts all the time before a few days ago, but then again I wasn't paying close attention.

I stopped at the Interstate battery dealer before posting today and they told me 1) the battery wasn't fully charged given their volt meter read 12.45 volts. Then I started the car and they measured the voltage again and it read about 12 volts. This led them to conclude the alternator wasn't charging the battery. I took their observations at face value, but decided to reach out to Forum members for the following reason. I've driven the car for about 100 miles since noticing the problem and the battery should have fully discharged if the alternator was completely dead.

I'll know more on Monday b/c the car was scheduled to visit the local independent Jaguar shop that day to investigate an issue of what the steering wheel seems to forget its position when I start the car. When I get there, I'll ask them to look at the charging system first and go from there.

BTW: What voltage is the meter on the dash actually reading? Is it the output at the alternator or somewhere else.

Again, thanks for the feedback so far.

Thom

 

 

Thom, when my alternator went bad, my first indication was a fluctuating voltmeter display on dashboard. Went to auto supply store who tested and concluded faulty alternator.

FYI- I didn't listen to strong warnings from experts right here, to only replace with Denso brand unit. Bad idea not to listen, take the time to find one. Costs all over the place, found one for similar price to auto zone standard alternator. Other places wanted over $600 (2x what I paid).

John

 

Thanks everyone for the advice. The alternator was on its last legs and is being replaced.

And thanks Jandreu for the heads up on the steering column. The extensive thread helped pinpoint what the problem likely is...

 

Sorry, this a delete of a message that was meant for another thread.