After an engine swap, 2003 XJ8 motor into my 2001 XK8 I am getting a Battery Not Charging message and red light on my voltmeter. I checked voltage at the battery and it was 12.8 Volts, with the engine running it shows 14.3 Volts. So I think the alternator is working.
I had missed hooking up the wire that plugs into the alternator at first, after plugging it in I still have the message and red light. Is there anything else I can check? Thanks

 

Noterman, try hard reset for a couple of minutes.


Wayne

 

Hi Wayne, I tried the hardboot, no help. When I turn on the key the volt gauge reads 11 volts. When its running it shows 13 volts. Also can someone tell me why my posts are not bold print?

 

Your voltage at the battery seems to be in order. Did you use you old alternator or the one off of the XJ8. I know it should not make a difference but the ECM or whatever controls the gages can "get it's knickers in a twist", an old English saying.


Wayne

 

I used the alternator from the XK8. It worked fine before the engine failure.

 

Noterman, Sorry but I'm out of ideas for the simple fix. Let the guru's see if they can figure is out and I look forward to the answer.


Wayne

 

are you SURE all the wiring on the plug is in place??? Didn't pull anything out? I replaced my o2 sensor on my car and it turned out being a pulled out wire in the plug on that one. I TOTALLY missed it after staring right at it many times. It was just pulled out enough to see it in plain site but I missed it.

 

I still have not solved my battery charging problem. I checked all battery related fuses, changed batterys, pulled the alternator and had it checked, replaced the alternator even though it checked good. I checked the plug that goes to the alternator it looked good, as did the two wires in the plug. I still have the red light in my amp gauge and battery not charging message. Not sure what to do next.
Quick review, engine off battery voltage is 12.23, running voltage at the battery is 14.24 volts. In the car with the key on the gauge shows 11.75, running it shows 13.0. Do the gauges ever go bad? I hate to tear the dash apart. I am thinking gauge reading is what turns on the red light and gives the battery not charging message.
Increasing engine speed is no help. Thanks everyone.

 

The 2 sense wires in the plug that goes to the alternator doesn't feed the gauge directly. It could be a harness problem. I'd also check the battery connections in the little bulkhead the ECM/TCM is and reseat the connectors (with battery disconnected).
Otherwise it may take ohm'ing out the 2 sense wires to wear they connect inside to make sure there isn't an open somewhere.


Dave

 

Noterman, are you using the ECM from the 2003 XJ8 or the 2001 XK8?

 

I am using the ECM from the 2001 XK8. Could that cause a charging problem?

 

According to this thread it should be OK: https://www.jaguarforums.com/forum/j...k-4-2-a-23763/

However, it says to use the front lower pulley from the 4.0. I wonder if they are different sizes and the alternator is turning too slowly if you used the 4.2 pulley?

 

The motor is a 4.0 from a 2003 XJ8 donor car so everything I think is the same.

 

OK. In 2003 I believe that Jaguar shipped both the X308 XJ8 (4.0) and the X358 XJ8 (4.2).

 

Noterman,

Early on you reported the battery voltage to be 12.8 (very good). Later you reported 12.23 (pretty bad). Are these correct? Have you been driving trips long enough so that the battery should be staying charged?

Are you measuring battery voltage between the "+" and "-" terminals, or between the + terminal and chassis ground? Please get one of each such measurement and let us know. (There needs to be some load, some current flow for this comparison. Headlights would do it.)

 

I checked voltage today. Voltage across battery is 13.70, positive terminal to car ground is 13.45. Headlights on voltage across battery is 12.72, positive terminal to car ground is 12.40. I attached the ground wire to the right front shock tower.
I looked at the wiring diagram for my car. I do not have a suppression module on my car. Could that cause a problem? I also pulled the cover off the ECM and it looked good.

 

Seems like not all of them have that module, its mainly there to keep noise out of the stereo. It shouldn't be the cause of your problem. You said you have already replaced the alternator?



Dave

 

I had the alternator checked, it tested good, I replaced it anyway. Replaced the battery also. No help

 

OK, I think we might be on to something. Voltage across the battery (+ to -) should be identical to voltage measured from + terminal to ground. In other words, there should be no resistance between the - terminal and chassis ground anywhere on the car.

I'd suggest removing both terminals, cleaning everything there, reattaching them securely and trying the measurements again. Also inspect the ground strap and its attachment to the chassis.

 

This morning I cleaned my ground straps and battery terminals. Now I have 12.88 volts at the battery using the neg. post on the battery and using the body ground. 12.34 volts with the headlights on. So I think I have good grounds with no resistance. With the car running I show 13. volts on the gauge. Reving up the engine is no help. I am considering replacing the plug with the two fine wires next.
Also I did not switch computers from the donor 2003 XJ8 to my 2001 XK8. Could that cause a problem?
Does a battery not charging message and light have to be reset or does it go away when the alternator puts out enough voltage.