2001 Jaguar XJ8. My mechanic replaced the alternator with a new one and replaced the battery with a new one however the new battery is not holding the charge because the battery is what is powering the Jaguar. Has said battery checked and charged at Auto shop. Running the battery dropped from 14.2 to 8.9. the other day with the battery not charging light on it a was fuse that was blown. The fuse has been checked, it is good the negative battery cable what's replaced it is good. The old one was put back on after the clamp was replaced. I am going to check the battery connection under the trunk lid. Where else would be checked to figure out why the alternator is not charging the battery? Yet it not giving the "Battery not charging" message.

Matthew

 

After the battery is charged back up, start the engine and take a voltage reading from the back of the alternator while it’s running. Also make sure the single pin connector is firmly snapped into place. If you still have no voltage from the back of the alternator, it’s possible it’s defective right out of the box? It doesn’t happen very often but I’ve seen it before. Could also have a burned up connection on the passenger side bulkhead in the engine compartment.

 

Take it to a guy specializing in rebuilding starters and alternators

 

did you make sure the battery and alternator are all new/working condition?

I had a strange case that glove box light stayed on with faulty fuse which drained the battery.. check any unusual battery drain on your car.

 

The power stud on the false bulkhead is my guess.

Probably did not need alt or batt but..................?

 

The alternator was effective from the box. The mechanic switched it out with a new one which is not defective It is charging the battery but the message on the dash is battery not charging. Ah the dance we do.

 

The alt was EFFECTIVE? Did you mean DEFECTIVE?
I NEVER get a rebuilt from an auto parts store because almost EVERYONE reports back that the INSTPK displays NOT CHARGING.

Jaguar parts dept will have proper rebuild and a good rebuilder will use Denso or Toyota parts to install in a Jaguar alternator but too many people report back that generic parts have problems with the regulator not compatible with the Jaguar modules and the alt actually does charge the battery but displays the fault.(incompatible?)

A good-used will probably work better than the auto parts alt?

Check the power stud and keep us up to date with the diagnosis.

 

what is the good source for a "good quality" Denso alternator?

for my future reference...

 

Your local rebuilder if you live in a city with more than a 100k people. They rebuild the things, almost always a Denso, new brushes, bench test and wait on your call!

First learned this years ago: had a Caddy that was noisy (wound up it was the AC), so I was replacing everything reciprocating instead of turning up the radio: guy down the street in Falls Church VA told me it was forty dollars if I brought the old one in or $150 if he had remove it: warehouse stocked end to end with alternators and starters ready to ship to which ever dealer or car parts store called: work bench with a motor, a belt, and a stand for the unit being worked on: bins of brushes, diodes, bearings, et al: took him about ten minutes to renew a unit. Even showed me what happened when an ex (RIP) had dropped a penny into the cigarette lighter . . .

Then with my last 308, replaced the battery, still had a light, took it to the guy up the street from Little Creek Naval Base: dropped it off and ten minutes after my wife had driven me home in her Nissan, the guy calls and says come get your car, all done. $200 or so!

 

We have a shop that is similar here, but of late finding him open is problematic.
He used to have a sign posting his operating hours, but no longer. Now it is
just a "catch as catch can" which is frustrating for those who have a timeline
they are expecting. I am unsure how he stays in business.

 

Yes the last alternator was defective from the box. The new one is good. Putting out 14.1 to 14.4 running and 13.8 at idel. However still says Battery not charging. When yes little Mr. Josiah Edward III it is charging.
​​​​​​
It is slowly creeping to 14.5 14.6 but only for a few seconds each. Don't think I'd like it to go any higher than that, correct?

 

Those numbers are a little high, but may be ok if the battery was severely low. After the
battery is returned to full charge, check it then. You still might wish to check for corrosion
around the connection on the passenger side bulkhead in the engine compartment.

 

14.1 to 14.2 to 14.3 on the street moving or not. 13.0+- engine off key out of vehicle. Battery not charging message still on. Going to do the hunt tomorrow. Anything I'm missing?


Car off, key out.

Running.

 

Can you go into the ECM and the instrument pack and clear the codes? If you can, after that perform a hard reset and see if that takes care of it.

 

How would I get into the ECM to clear the codes? I do it on my GaragePro OBD2 Bluetooth app. I did it yesterday a couple of times and it starts on. I did the hard reset. But had a lot going on then and think I did it wrong. (Key off. Unhooked Negative battery cable. Turned key on to run position. Held cable to positive for 30 or so seconds. Turned ignition off. Reattached negative. Started car.) It went to it's normal idle and message still on.

 

Hi Matthew,

The battery charge signal to the Instrument Cluster comes directly from the voltage regulator/alternator on a Yellow wire. As Addicted2Boost advised, the first step is to confirm this wire is securely connected at the alternator. Also, there are at least two connectors in this circuit between the alternator and the IC, one on the engine bay firewall behind the engine, and the other at the base of the left A-pillar inside the footwell. If you can access these connectors, it would be prudent to disconnect them, flush the terminals with electronic contact cleaner, allow to dry, then reconnect. Also check for rodent damage to the Yellow wire in the engine bay.

Another possible cause of your issue is poor connections in the battery power connections between the battery, fuse boxes, alternator and starter, and also poor connections in the ground circuits, which can lead to poor battery charging and strain on the alternator.

You mentioned that the battery negative cable was replaced. Others have already mentioned the need to clean the false bulkhead battery power stud in the engine bay. I would also recommend that you disconnect and clean all the nuts, wire eyelet terminals, megafuse blades and threaded studs in the High Power Protection Module in the trunk. Clean both ends of the engine ground strap. While you're at it, clean all the ground points you find, including the Engine Management System ground stud on the left inner wheel well. Clean the battery power connections at the engine bay and trunk fuse boxes. Not all of these are suspects for your current symptom, but even slight corrosion (often white in color) adds resistance to these circuits and can cause all manner of difficult-to-diagnose electrical gremlins.

Another possibility is a loose connector at the IC, or less likely, an internal problem in the cluster.

You can download the wiring diagrams for your car at this link, thanks to motorcarman and Gus:

Jaguar X308 Electrical Guide 2001

Cheers,

Don

 

It turned out to be that the two pigtail wires were dinked and destroyed to the point it was a weak signal. There was also another wire barely nicked. The two pigtail wires reconnected made the Not charging light go away. However it started to come back on randomly. The Battery not charging light came back on last night only at 11.3, it's not charging. Loose. There is now only 2 inches of wire left on the pigtail and other ends of wire only go to amor valve cover gasket. After removing the amount of bad wires.
Plan Is to replace the pigtail connector at the back of the alternator splice the two wires going from it to the wires coming from the wiring harness the top of the engine. Concern is the length of the wires coming out of the new connector.

Would pigtail wires to joint to wires to joint be okay?

Matthew

 

Hi Matthew,

You may need to add some additional wire so that once you've spliced them together there will be adequate slack in the repaired wires.

Were your wires chewed by a rodent?

Cheers,

Don

 

Two of them were from alternator the other was orange or red (being color blind isn't fun). I'm going to take the old plug in with me to make sure I'm getting the right gauge. Found a whole engine wiring harness that I should get. Numerous connections are broken or brittle and wires are brittle.

Matthew.

 

Different cars have a wide variety of insulation material used for the wires. The best is silicone
however the Jaguar engineers probably were most likely not consulted as they tend toward decisions
based on longevity/cost rather than cost alone. I have not experienced much "wire embrittlement" on
the Duchess, so it is difficult to pin such conditions down on the same model car. I do know that heat
is a primary culprit and, of course, chemical solvents that are used in degreasing engines,
.