I do wonder, how come i could get a "Generator/Battery Fault" and with the warning still on, measure 14,5 Volts on the battery?? Seems really good to me.

Unfortunally the gearbox thought so too, that voltage was low and threw a "Gearbox Fault" on me as well..

Why is this? Is it just to wipe my tears and coff up for a new generator? ... or might it be something else.. cheaper?

/E

 

At first glance, your charging system seems OK.

But What is the battery voltage with the engine OFF and has been sitting overnight OFF ?



it needs to be 12.6v minimum, or higher.

​​​​​​​ How old is the battery

as has been mentioned many times, putting a battery tender on the car whenever it sits overnight or longer will banish many electrical gremlins and fault messages.

best ones: CTEK , NOCO Genius (5 or 10) , and the Delran Battery Tender +

Z

 

[QUOTE=Einhead;2845828
that voltage was low and threw a "Gearbox Fault" on me as well..

Why is this? Is it just to wipe my tears and coff up for a new generator? ... or might it be something else.. cheaper?

/E[/QUOTE]
In my case, a poor connection on the bottom side of the under bonnet, driver side (USA) fuse box was partially robbing the TCM of the full 12v supply. To my embarassment, I had only front probed (false open circuit 12v reading) the TCM connector. (YouTube has many clips on proper "back probing" which may reveal true voltage division) I carefully (brittle plastic) cleaned those bottom connectors as well as the top fuse connections on that fuse box. That was 12 years ago has been flawless ever since.

 

Since its widely mentioned here on the forum that a poor battery in sevral cases is to blame for various faultcodes i bought a new one, the biggest AGM class battery i could fit, so battery is most likely not the cause.. i should last a night or two without dropping to bad in voltage.

With ignition on, i took a measurement direktly from the generator plug on the two powersupply leads; one from the fwd fusebox and the other supply from the trunk fusebox. They matched the battery voltage within .2volt, so the generator is getting what its supposed to get il guess..

 

I don’t see the answer to this question:

But What is the battery voltage with the engine OFF and has been sitting overnight OFF ?


it needs to be 12.6v minimum, or higher.

I also purchased an AGM battery in the correct size (a larger one won’t fit) . Nevertheless I had random spurious engine faults messages including the dreaded “Engine Fail Safe” message. The NAPA AGM battery was less than 6 months old and the charging system was completely within factory specifications.


Just a few minutes of forum searching convinced me that a battery tender would be a useful addition to my maintenance regimen. That was seven years and several months ago. The battery, and battery tender, are now 7+ years old and working better than new.

My 2002 XKR has become the most reliable used car I’ve ever owned. More reliable than all the vintage Shelby’s, Mustangs, Jag e types, Triumphs, VW’s, and 240 Z’s that I’ve owned. Certainly not what I was expecting given all the horror stories that abound. I’ve spent about $200 over a 7 year period on non consumable parts (a heater valve and a CPU fan). Knock on wood.

li have to give credit to the forum on pointing me towards how to maintain the car in such a way to keep it problem free. Even a retired professional mechanic like myself can learn from the experience of others. Thank you Jag forum.


Z

 

Which voltage was low?

It's possible that the alternator regulator is playing up. Are any of the symptoms similar to this?:
https://www.jaguarforums.com/forum/x...90/#post714167

 

All alternator problems show up as a defect in the warning light operation Do what Zray says not your version of what said

 

The measurements i took was with ignition on, and measured 12.6 ish votage on my checkpoints witch should be just fine. I did measure between the alternator plug and the associated fuseboxes to see if there was any losses in the leads, but it was ok.

I did check the link provided by michaelh, and i think im in for a alternator replacement since my symptoms more or less exact mirror the problems mentioned there.

From what i have learned, the alternator has no buillt in fan to help keep it cool and instead it relies on that little duct attached to it to provide cooling air... as it seems, that duct is the first thing that gets tossed.. somewhere.. at oil/oilfilter changes.. and sometimes fails to be installed again. My car did not have that duct.. so it has most likely been living without it for a long time and as a consequense the alternator life most likely has been shortened dramatically by high temperatures over time..

/E

 

with engine running at say 2000rpm you should get 14v or a bit more .if that is so and the WL is out the alternator is OK
PS it has an internal fan

 

I went through 3 NAPA batteries in less than one year. I gave up after the 3rd one died. After checking the voltage from the alternator, I bit the bullet and got one from the dealer. It's been about a year on this one with no problems.

 

were those the conventional batteries or the AGM type ? I’ve had good luck with my NAPA AGM battery. So far it’s going on 7+ years.

According to Google’s Gemini A-I “East Penn Manufacturing makes the NAPA battles in the USA.

i think they make barriers for other retailers as well.

Z

 

They were the conventional batteries. Should have mentioned that the car has always been kept on a battery tender.

 

Today i think i got the final proof that my alrernator is shot..
Started the car in order to take it for a little sunday drive.. and right away i got ”Generator Fault”.. i let the engine run for a few minutes to ser if it would go away.. witch it didnt.. So i killed the engine and started it again.. No faults this time.. hmm.. then, in the corner of my eye i saw that the voltmeter on the dash was suddenly vent past 15 volts followed by ”Gearbox Fault”.. a few seconds later it dropped to below 11 volts.. and then settled around 13 volt..
Thats it! New alternator on order…