Hi all,

Firstly, apologies that this is going to be a long post.

A few months ago I had problems with alternator and starter motor issues. All was resolved when a new positive power cable from the battery to starter motor and replacement alternator was fitted at the end of July.

Well, about 6 weeks later and I am experiencing the dreaded battery light again. Symptoms are that occasionally after about 1 minute of being started, the battery light comes on. Power off, lock, unlock, start up again and all is fine until the next time it occurs. But it's annoying and makes me wonder if something more sinister is lurking there. I have noticed that if I turn the key to the position where all the dash goes live and leave it there for about 15 seconds then start the chances of the battery light coming on decrease greatly, but this is not guaranteed.

So far I have changed:-
- Alternator
- Starter Motor
- Positive Battery Cable

The battery was not swapped but has been tested three times as fine.

However, tonight it was worse than usual...

5:35pm - got into car to come home from work. Started up and let it run for a minute, no battery light came on, headed home.

6:05pm - arrived home.

6:15pm - had to go out. Started car with no AC on, left it for a minute, battery light came on. Switched off, locked, waited 10 seconds, unlocked, started with no AC on, left it for a minute, battery light came on. Switched off, locked, waited 10 seconds, unlocked, started with no AC on, left it for a minute, battery light came on. Whilst the light was on I read the voltage from the battery - 14.31v. Seems normal to me. So, switched off, locked, waited 10 seconds, unlocked, started with no AC on, left it for a minute, battery light came on. Switched off, locked, waited 10 seconds, unlocked, started with no AC on, left it for a minute, battery didn't come on, so off I went. Turned AC on. About 10 seconds later, battery light came on. Pulled over at a safe point, switched off, locked, waited 10 seconds, unlocked, started with AC on, and carried on the journey. No more battery light - yay!

6:30pm - finally arrived local Sainsburys. Car turned off.

6:40pm - left Sainsburys. Started with no AC on, left it for a minute, battery light came on. Switched off, locked, waited 10 seconds, unlocked, started with no AC on, left it for a minute, battery light came on. Lost interest, started it up and drove off. About a minute into the journey, battery light came on. Switched off, locked, waited 10 seconds, unlocked, started with AC on, left it for a minute, battery light came on. Pulled over at a safe point, switched off, locked, waited 10 seconds, unlocked, started with AC on, and carried on the journey. About a minute later, battery light came on. Pulled over at a safe point, switched off, locked, waited 10 seconds, unlocked, started with AC on, and carried on the journey. About a minute later, battery light came on. At this point I didn't care as I was 20 seconds from home so just pulled onto the driveway and turned him off for the night.

I am fairly confident that tomorrow morning when it's time to go to work I will have no problems.

I have also noticed that once he gets going with the light not coming on, that's it - it stays of until the next shut off and maybe the problem comes back when I try to start again. Did 150 miles on Monday night after the light had come on 3 times trying to start after a quick stop off somewhere with no more repeats.

Someone has suggested there may be a sensor or similar on the alternator that could be causing the issue - can anyone identify where this is so I can check it out?

One more final bit of information that has hit me. When the original alternator failed over a year ago, the recovery guy suggested that the battery was also fried and would need replacing as well, however at the depot (had to change trailers) on the way back his boss had a look and said that he thought it would be Ok. This is the same battery that has now been on 2x failed alternators in the last 18 months or so. Is it possible that this simply is a battery problem? It has been checked but you never know, especially as it is getting worse.

It's just getting annoying now - I don't know if I trust the information that the batterylight is giving me based on all this. Also means I don't have a lot of trust in the car at the moment which isn't good - just wonder if it is going to let me down at some point...

Thanks in advance all and sorry for the long post.

Regards,

Tim Watts

 

The negative cable corrodes also.

Enjoy
D

 

Is it recommended to drive him with the light on, not knowing what's really going on under there...?

TMW

 

So, have done a few journeys today with the TEST mode activated so I can monitor the battery voltage.

Typically, no battery light today and I have now done 4x trips...

But, pattern seen thus far is, start up and there's around 14.2v (fluctuating slightly) and after about 3 minutes, this drops to around 12.4v (again fluctuating) where it stays for the remainder of the journey - from other postings I have read I believe this is normal but could be wrong?

Will see what happens on the return from work and other trips over the weekend...

TMW

 

Your voltages are a bit low for the Jag...especially that 12.4. While it is running, I'd expect to see 13 and change. When it firsts starts, it should be high 14s, almost 15 for a few moments.


Check the resistance on the negative cable.


By the way, the Jag is REALLY sensitive to battery voltage and condition; a 'regular' car will live happily with a 75% (good) battery for years. An X will start to give ypu grief at 85% and really act up by 80%.


Oh, and don't bother turning off the AC. Set it to Auto and forget that it exists...the computers will handle it for you.

 

Sounds like my old totalled 04 X type.

Where did you get the replacement alternator from? If it's not an original or original quality, you might have added an additional problem. That's what I did burying a OReillys alternator

With my "new" 05, I purchased brand new battery cables before the car was even delivered. It's important to replace both at the same time.

 

Hi all,

So, an update following the breakdown and battery swap that unfortunately happened on Friday. Car wasn't used any more Friday after I put the new battery in, but yesterday on the other hand (sorry if this is boring, but there may be some relavence - somewhere!)...

Saturday:-

10:10 - drove to next town over (sounds grand - it's not!) - 5 miles - 15 minutes.
12:10 - drove back home again - 5 miles, 15 minutes.
13:30 - drove to local tyre place as needed to replace one - 1.5 miles, 4 minutes.
13:40 - drove to another local tyre place as the first had no stock - 1 mile, 3 minutes.
13:50 - drove to local cashpoint as alternative tyre guy is cash only! - 1 mile, 3 minutes.
13:55 - drove back to 2nd tyre guy - 1 mile, 3 minutes.
14:30 - drove home having had new tyre fitted - 2 miles, 6 minutes.
14:45 - drove to supermarket - 1.5 miles, 4 minutes.
16:15 - drove home - 1.5 miles, 4 minutes.
17:30 - drove to see family in Uxbridge - 42 miles, 55 minutes.
23:55 - drove home again - 42 miles, 50 minutes.

Through all of the above, the battery light did not come on once - yay!

Sunday:-

13:00 - drove to decent garden centre - 22 miles, 30 minutes.
15:00 - went to drive home from garden centre - 1 minute after leaving, battery light came on - AGH!!!!!!
15:01 - powered off and on again, battery light came on after 1 minute- AGH!!!!!! Powered off.
15:03 - started up again, battery light came on after 1 minute- AGH!!!!!! Powered off.
15:05 - started up again, no battery light after 1 minute, drove home - 22 miles, 30 minutes.

So, after having a day of excellent driving on both long and short journeys (and some quite short delays between journeys) today the dreaded light was back.

I think I am going to replace the negative battery cable next - positive is already done so that seems to make sense. I am assuming this is one I can swap-out myself. Spotted when changing the battery on Friday night that one of the ends goes to the grounding point beneath the fuse box but couldn't see where the other went - is it easy to spot? Assume you take the battery holder casing thingy out to get access?

Thanks as ever.

TMW

 

https://www.jaguarforums.com/forum/x...cables-105946/

 

Was your issue resolved as I’m experiencing the same thing?
thanks!

 

Ya was your issue resolved, I sometimes have same issues.

 

I had the false alternator light issue too and did a lot of research on this forum. It seems like it's generally a battery cable going bad, typically the positive one. On the advice of one forum member I took the cheap route and installed a generic parts store cable between the alternator and positive battery terminal to supplement the factory cable. 3ft, 6 gage, with 5/16" lugs was the right fit and you should be able to pick one up at a parts store or online for not much more than $10. The nut on the alternator terminal is a bit of a pain, but if you remove the air box and have a long set of extensions and maybe a wobble extension you can access it. I haven't had the alternator light come on since.

I also picked up a USB charger from amazon for just over $10 that shows the battery voltage. I just leave this plugged into the lighter and if I want to check the battery or charging system voltage I just flip open the ashtray cover. Plus now I've got a couple of handy USB charging ports. When I got the false alternator light it was actually charging fine fyi.

 

XTypeHI, thanks for replying.

Does the cigarette light voltage display give the same readout as the onboard diagnostic?
I added a new cable from alternator post straight to the battery yesterday. It cranks at 14.5 but steadily drops off to 12.6 after a few miles. The dreaded light did not come on but when I stopped I did double check the voltage with a multimeter and it was close at 12.9.
I’m wondering where the onboard diagnostic reads from and if the cigarette lighter readout you have matches the onboard screen ..

Thanks,

John



lighter

 

I never compared the cigarette lighter to the diagnostic display, but I did take a look at the OB2 output, I think the lighter was maybe .1v lower. It's pretty common to see some voltage drop, certainly .2v, between the alternator or battery posts and interior of the car. I don't really love the look of the positive cable between the battery and fuse box in terms of being a high quality connection. It's always worth making sure the battery terminals and your grounds are clean and shiny too. When I added the extra positive cable I was disappointed it didn't bring up the voltage a tenth or two, but it did still fix the false alternator light problem. I'd just keep an eye on it and see how it goes for now,

 

stop ! its the positve cable on the alternator going to the battery,if i remember correctly its a 13mm nut you can get from under the car ,then you add a battery cable to it and run it under the air box to the battery ,your done ,i think i got the cable from advance auto part thisone below
https://shop.advanceautoparts.com/p/...ery%20%20cable

its very hard to kill a x-type alternator ,you cables are overheating with high resistance

 

Check all of your grounds before anything, including the main (+) wire to the post on your alternator. If this is bad, it would simulate a bad alternator, but it could just be a bad wire or connection. A "battery test" at an auto parts store could say your alternator is bad without actually diagnosing anything. They'd just go 192.168.100.1 192.168.1.1 jpg to pdf off a reading on a handheld tester.

 

Throwing anther two penance in here.!
Have you at any point allowed the battery to run flat for a period of time?
Older batteries that run flat do tend to suffer even after recharging or jumping the car. They can give funny readings to, you should be getting up in the 14V if you're getting below its a good bet the battery could simply be coming to the end of its life.