Hey guys,


So i had my whole a/c unit replaced about 2 months ago and also that same day I had my tires replaced. While I was driving home I noticed my battery light came on? It seems like it may have lost some power put nothing severe. I got home turned off the car, and about an hour later I drove again and now the battery light was off. A few days later it came back on again after driving for a few mins. This has been going on and off since I had the a/c and tires changed, any suggestions? please dont say it's the alternator. Would corrosion around the battery terminals cause this? I havent checked that since it first came on. The battery light has stayed off for about 2 weeks now, but it just started up again. What gives?


Dustin Schaffer

 

Dustin, as much as you may hate to hear this, this is what I have fund out about Ford alternators: they tend to fail at higher RPMs. So, the next time you start having issues, check out the RPM that the engine is at. If you are up around 3,000 RPM or more, then you are looking at a bad alternator. If it is coming on at all RPMs, then let me know and I will give you a few checks to make and we'll get to the bottom of this in a heartbeat.

2 things that you can check right now is:
1) on the side of the alternator is a small plug. Verify that this plug is seated fully. It is possible that as they were messing with the compressor, they bumped this plug and now it is hanging on by just a little bit, leading to intermittent problems.

2) verify that the output wire (large single post on the back of the alternator) is tight on the terminal and that the wire is in good condition. You get a mechanic that isn't too easy on a car, they can damage wiring unintentionally, leading to other issues.

If you need more help, let me know.

 

@dmsdvls3 I get the battery discharge light, but only when it is really hot out, its not on at startup then i see the light appear, so I normally stop the car turn off the engine and start again and it goes out. I heard there is a potential short on a wiring loom near the radiator, but I've not investigated as of yet.

 

thanks I'll check it out!

 

I have the same problem that David Moo described - my battery light comes on intermittently, usually when it is hot out.

 

I had alternator discharge and then replaced with new bosch. System has been checked and rechecked but my battery light will not go out. I am also getting a message on digital display that battery is not charging but it is charging... any help. I checked all connection,,, cleaned post and all to no avail. I finally put piece of black tape over it because I am embarrassed that all these light are on in such a nice car. People might think I cant afford to fix but I fix her when she is broken but these gremlins are killing me. PLEASE HELP. I checked all connection in trunk and took out back seat to see if wire cut. nothing

montero Z

 

Could it be that the battery/gauge or the digital display need to be replaced on these battery light problem. I know how to take off wood grain ..as this weekend I tool off to look at guage but went no further. once cover pops off there are 3 screw holding the the 3 guages in one housing. at least I took that bad boy off but what now???actually had air bag cover off also. I checked every last fuse in the car in all location and nothing.

 

monteroz1, let me take a look at the diagrams once i get home. I should be able to solve this for you with a check or two. From the sounds of things, you have either a problem in the instrument cluster or a broken wire between the alternator and the instrument cluster. But, let me confirm that with the drawings. How are you with a multimeter?

 

Disclaimer: I next to nothing about cars, but here's what happened with my intermittent battery light problem: I was told I needed a new alternator. But I had a lot of corrosion on the top around where the negative cable connects. Cleaned that off and replaced the very corroded negative cable and that fixed it. I also left the top of the battery box off so it doesn't get so hot. No more battery light. I had the alternator and the battery retested and they're both great. Yes, corrosion can definitely screw you up.

I don't know if this will help, but good luck!

 

Oh no, Jo is giving information now. He he he hehe. Just kidding girlfriend. Laugh with me.

 

you guys need new cablespostive and neg, but positive is the biggest offender. The X is the worse in the Jaguar fleet for cable issues. I have seen 2 alternators replaced in our shop since 02 and both were not the issue but the cables. There are several ways to check. The easiest without tools is when the light is on, touch the positive and neg cables clamps on the battery posts. The postive is useally alot hotter than the negative due to higher resistance that creats heat. Also you can out the instrument pack in engineering mode and scroll to BATT voltage and monitor while you drive. To do this press and hold the trip button and start the car still holding the button. When it goes into engineering mode scroll through all the acronyms till you reach Batt. You can now monitor battery voltage and whatch what it does. The normal bad cable operation is is charges fine till your driving awhile and the cables get hot from internal resitance. Then youll see battery voltage drop to 12.6 or less and when lower enough will trigger the batt light. I always recommend new poisitve and negative cables along with the link from the postive to the engine compartment fuse box. This covers all bases the first shot. Or you can start off 1 by 1. But we put cables on like hot cakes for this issue, and the light on while driving and after awhile is the a dead give away..

 

lmao! I'm laughing with you, Chris! It is funny, isn't it? Hey, I did put in my "disclaimer" first! lol

 

Also bought new ground cable for trunk connection and cleaned all battery post to no avail. This is a large ground cable under the car by alternator. It is not than frizzled. ? checked all fuses too! nothing changed????i do not have much hair left. will post pics of jag but headed to gulf coast car cruise o n thursday. anyone there at cruise call me 4040-431-3875 (gulfport ms). working today to get new plugs; clean mass air floe sensor and throttle body and going back to stock air box. no cold air intake this car any longer ....car is too sensitive. keep me posted of any bay light solution. i have learned a lot about this car...

 

I will check the positive cable now . I replace negative from battery in trunk from auto zone. They had one listed for $8.99,. Is this OK. Dont want to buy jag cable unless absolutely necessary. thanks a million

 

I have a similar issue. Once I start my car the light will occasionally turn on after 30 seconds or so...

Sometimes it does sometimes it does not.. No idea why honestly..

 

not good at all. is that a new dance?

 

not good at all.

 

Hmmm...we seem to have X-Types and XJs in the same thread. Anyways back to the X-Type. As Brutal said, check that positive cable on the X-Type. On mine it ran across a bolt on it's way to the fuse box. Battery light came on, DSC fault flashed and then she completely shut down on the freeway. Finally diagnosed it by moving the cable and when it arced, due the insulation being worn through and started the small smoldering fire, I knew I had located the problem.

 

Thermo I still have battery light on permanenhtly w/ display indicating battery not charging. Think I should check ground strap under car. Again, have replaced battery cables in trunk (pos and neg). sometime the message scrolls and sometime it is frozen. Any ideas? you were going to check wiring diagram which I also have downloaded from internet and trying to see what I can see. 98 xk8