2jag, the ECM controls the voltage output of the alternator. It may be possible you have a high resistance in the control wire. If you want to dive into this, let me know. I can break out the schematics and see what we can find for you.

 

FOr anyone with a battery light on in an x type check the back up lamp fuse before replacing alternator. The genius at jaguar decided to put the alternator circuit on the same circuit as reverse light switch and lights themselves. And they should not hide alternator it in the middle of the fuse description. hope this helps

 

i had exactly the same problem. my battery light came on when i stop to fill up or i turn off the engine after a long drive and start the car again after a few minutes. i battled with the issue for a while till my mechanic suggested we check the CABLES and it turned out that the -ve cable needed changing cos when he cut open it, we all noticed that it had changed color from the usual orange color to black. The same -ve cable got so hot when the engine is running and u attempt to touch it meaning that the resistance in the cable was so high that the energy is converted to heat. So though everything worked fine in my car the battery was not charging so well or at all.
Last saturday i finally changed the -ve cable and since then i have not had the light on the instrument cluster, infact am just coming from 245mile trip which i stopped a couple of times and turned the ignition off but still NO LIGHT.
My advice is CHANGE THE -VE CABLE. infact its very easy to do as it connect to the body of the vehicle by a bolt. You will notice this when you disconnect and remove the battery and the battery case.
Good luck mate!

 

i am a new member aussimark could tell me how to post a question on this page

 

I have a 2003 X type 2.1 SE, 39857 kms & has a battery warning light problem. It comes on & off while I'm driving. When it happens, I stop the car, turn the ignition off & start the motor once again. The ignition battery light goes out & can be like that for some time. This problem happens on a cold motor or hot motor. I've read your forums about the VE cable to be replaced. I've checked the heat of the cable manually & it's ok. I've had the alternator totally overhauled, checks out 100%. When battery light is on it's still charging at 14 volts. The only thing I've observed with the battery light on is that when I turn the motor off, there's like a reset click sound. I then restart the vehicle & the battery light is again off. This vehicle only does short trips as evidenced by the low kms. I've read all the forums but my problem could be a sensor. Jaguar Australia tells me that the alternator puts out 15.8 volts max which is standard for 2003 models. My Gold Coast auto electrician does not know what to do next.

I hope someone has some ideas to help me out.

Thank you.

Aussie Mark

I

 

yes you can avoltage regulater on its own to fit ln australia $170 AUSSIE MARK

 

Hi! Does anyone know the part # for this cable? Could not find it

 

Hi ghettomike

On your battery you have a red positive & a black earth which bolts to the body of the vehicle from the battery. This is the problem guaranteed. The earth wire overheats because it is too thin. Get your auto electrician to make a new one up as thick as your index finger. After being successful in fixing the warning light on the dash, it cost me approximately A$700. This will fix the problem. It's the earth wire from the battery. Seems to be a fault with the X type Jags. Goodluck!

AussieMark

 

Further to my earlier message to ghettomike, do not get involved with people telling you that it's the alternator, regulator or charging rate. It's no more technical than a voltage earth cable which is the black lead that runs from your battery & bolts inside the front guard. As you read through the other messages, it said voltage earth cable to replace at a cost of approximately A$20. As you can see I paid the price of investigating the problem, from the alternator to the battery. Even my auto electrician was baffled. Once I told him about the earth cable, he checked it & found that it was a bad earth which is sending signals back to the computer that there was a fault which in turn showed up in the dash as a battery warning light.

AussieMark

 

The battery light in my x type was solved by cleaning the negative ground to the chassis under the battery is support box. Remove the battery, remove the plastic box and there are 2 ground cable. In my case the right ground wire bolt snapped because it was so corroded. I cleaned the cable end and attached via another bolt in the area.

 

My battery light just came on and a message came on over the mileage number. The book says its probably the alternator, as you mentioned in your message. Wondering if the A: 1802.2 number is related to the alternator, do you know if it is?

Any help would be appreciated.

 

My battery light just came on and a message came on over the mileage number. The book says its probably the alternator, as you mentioned in your message. Wondering if the
A:1802.2 number is related to the alternator, do you know if it is?

Any help would be appreciated.

 

Cable, first off, welcome to the Forums. Lots of good people here and tons of useful information. But, we ask a small favor from you. Please stop by the New Member Section and introduce yourself. We pride ourselves in being a better car group and as part of this, we like to get to know one another. This will also give you a chance to meet those that make this place what it is.

As for your problem, I would be looking at the battery cables before going after the alternator. Past experience has shown that the alternators in this car are pretty stout and normally do not fail (there is always the one here and there). There are lots of threads about replacing the battery cables. If you don't mind a little drive, I live south of you by about an hour in California, MD. I am sure we can get you taken care of and back on the road in 100%.

 

This was helpful, in more ways than one. I went to the new member page and posted (had no idea that was there) so pointing me in that direction was great.

I have a 2002 2.5 and I have no idea what I'm doing. It's my 1st "luxury" car and I want to take care of it as best I can.

Appreciate the help! Now, if I can find help on getting my iphone to work through the system.......

Back to the forum!

 

Hi folks. Here is the issue with my charging light. The light comes on at random times of the cars running so this morning I did a voltage check and watched it and here were the results.

Initial start up and running voltage was between fluctuating between 15 - 16 volts and a strange noise from alternator.
After warming her up the voltage dropped to 13.9 both with everything switched off or with every electrical item on the voltage stayed at 13.9 but the charge light is on so I turned car off started her up again and this time voltage went to 14.4 and stayed there both with nothing on or everything on and no warning light on but every so often the engine revs would drop like a drain had been put on alternator and voltage would drop to 13.4 but within a few seconds it would settle at 14.4 and stay there. If voltage is around 14.4 then the light stays out. I am thinking the alternator is on its lasts legs. I have added in an extra earth lead as it looked badly corroded at its anchor point and would not come out plus I checked for a voltage drop between alternator and battery and it was 0.02 of a volt so think that lead is sound. Any idea's

 

An update. I had car in my garage and went into the test menu on dash board to watch the voltages from inside the car. When I started it the voltage was 14.4 but soon shot up to 16 before settling at 13.8 which brought the charge light on. The interior lights and headlights are going bright and dull which coincides with the alternator charging rates fluctuating but it soon eventually settles to one voltage. The car revs also change as the charge rate changes which shows that the load is increasing and decreasing on the engine.Is there anything other than a faulty alternator that can cause this unstable charge rates. I hope that it does not spike anything with the high 16 volt charge it is giving out at times although the peak 16 volt is only for a fraction of a second before it settles but the ironic thing is that it is never dropping low enough to allow the battery to drain as the lowest it has shown is 13.8 volts with everything including rear demister on.

 

I'm new to this forum and apologize if this is not the best way to obtain advice on the same issue, but my 2004 x-type 3.0 is making me and my mechanics UN-enthusiasts.

As a result of advice posted here, I have run the TEST Mode (on the interior display) for the past 3 days. At startup, the Volts are 14.6, 14.7 or 14.8. THEN, at approximately 2 to 2-1/2 miles - WITHOUT any accessories running, the voltage DROPS to 12.5, 12.6 or 12.7!!!

When the battery light comes on, I can stop the car. Wait a minute. Turn it back on and it is again at 14.6 or 14.7 or 14.8 for another 2 - 2-1/2 miles - then it drops to 13.1 or 13.2.

If this is simply a heat issue, I don't understand why the voltage would not, again, drop immediately after startup? Why does it take another 2 - 2-1/2 miles of driving (40 mps at 1500 RPMs) for the voltage to drop???

I showed my mechanics information from this site and tomorrow they are going to replace the positive and negative battery cables. Is there something MORE they should check. They are losing patience with my car and I am having nightmares about the lack of a solution.

The problem was originally evident when my battery light came on while I was running the AC during 100+ temperatures. At the time,I simply thought that the AC was drawing too much power. Since then, I have experienced the same problem with NO Accessories running.

I don't know what the actual voltage ratings were at the time, but after discovering the TEST mode for the interior display, I noticed the battery light coming on at approximately 12.3 volts.

I've already spent almost $1000 in alternator replacement (which I now think was probably not necessary) and electrical diagnosis. The mechanics have now replaced the previous remanufactured alternators with an Original (salvaged) Jaguar alternator and the battery light has NOT come back on - however, the TEST Mode numbers show that the car is starting at 14.6+ and dropping to 13.1 or 12.9 after 2 miles.

I am now wondering if this problem has always existed but the lack of a battery light led me to think everything was OK - OR - if the oppressively high temperatures in California (100- 118 degrees) have exacerbated the problem.

I need a BIG BRAIN to help me before I get an ULCER. I really do LOVE my car, but no longer know what to do to keep her healthy.

All advice much appreciated.



Can anyone tell me PLEASE why

 

Replace the battery cables and see what you have then. The numbers do seem low at the 2.5 mile point. Just for grins, if you have the instrument cluster in the diagnostic mode, when the voltage drops, turn off everything electrical that you can to see if the voltage will come back up. If it does, it could potentially be an overloading issue. If the voltage remains low, then we are looking at a bad wire some where. This is where the battery cables will be the most likely suspect based on past experiences with the car.

 

Thermo: I have been running the TEST mode on the dash display to watch the battery voltage. It consistently drops from 14.6 or 14.7 at startups to 12.8 or 12.9 with NO electrical accessories on. When I run the AC the 12.8 goes down to 12.4!! I discovered the problem when my battery light would come on during got weather while I was running the AC. My mechanic is replacing the positive battery cable harness today. He has run out of ideas and patience.
Any further advice is tremendously appreciated.

 

californiagirl, I would need to look at my electrical diagrams (on travel, don't have them with me), but a reading that would be interesting to take would be the field voltage going to the alternator. This could be accessed from the ECU. If the voltage is down around say 7 VDC when the voltage output of the alternator drops, then that would tell me you have an ECU problem. If the voltage jumps up to say 12 VDC (ie, the alternator is being commanded to raise the voltage), then this would indicate that your problem is either in the alternator or the wire running between the ECU and the alternator. Since you have replaced the alternator, this would pretty much leave just that single wire. What can be happening is this single wire is damaged and has a high resistance connection in the middle of it. When the wire is cold, the resistance is minimal and therefore the alternator can achieve the desired voltage. But, after the engine starts to warm up and the wiring gets warmed up from pulling lots of power, this resistance grows larger and therefore starves the alternator of power to make the correct output.

An option you can try that will prove this "bad wire idea" is to take the car out for a drive and let it go into this fail condition. Pull off in a safe location and be watching the battery voltage as you put the car into Neutral and rev the engine up to say 4,000 RPM. Does the voltage remain constant or did it rise up to a correct value. Without getting into how an alternator works, if the wiring is bad, you should see the battery voltage come up some. If it remains low, then you are looking at either a broken wire (and it is making only intermittent contact) or the problem is elsewhere. This can be resolved by measuring the field voltage on the alternator itself to see if it is the same voltage (within 0.5VDC) of what is being outputted by the ECU. If the voltages are close, then your problem is not the wiring. If they are dramatically different, then this confirms the wiring being the issue.