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Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15522
Experience:  12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
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I have a charging problem with a 2002 X Type manual 2.5L. I

Customer Question

I have a charging problem with a 2002 X Type manual 2.5L. I took my car for an injector cleaning, due to a "misfire", and when test driving the vehicle the battery light came on and the car started running lumpy. My mechanic found code P1629, plus a few others and advised me to change the alternator He was only getting 12V at the battery with it running. . I replaced it with a used unit from an automatic I had broken for spares, but the light still would not go out .I fitted a voltmeter in the power outlet and was getting 14V, but after abut 10 minutes the voltage dropped to 12.3, but the light was on al the time.
JA: Do you have a scan tool to read the codes?
Customer: I took it back to the garage and they have checked some things. It is still giving a P1629 code and it charges at 14 volts after starting, then drops to 12ish volts after 10 minutes or so. The light stays on all the time.They have been scanning and checking codes and they can reset the light, but it comes back on.It is still there tonight and they are thinking I should fit a new alternator - or it could be the PCM. I changed the belt with the alternator. Im just worried about the same code with 2 different alternators may suggest a different problem. Any ideas or advice?
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Its at the garage, but I work with them to fix stuff
JA: Anything else you think the mechanic should know?
Customer: I think you have it all for now.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Jaguar Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Jaguar
Expert:  Richard replied 1 year ago.
Is the battery and engine light both on?
Customer: replied 1 year ago.
No just the battery
Customer: replied 1 year ago.
The check engine light was on but I replaced the o2 sensor while the work was being done and it is now off.
Customer: replied 1 year ago.
Hi Richard, not sure if you are online. Having some log in issues here. Any follow up please?
Expert:  Richard replied 1 year ago.
same problem here but looks like it is working. We may have a problem with the positive and negative battery cables causing a voltage drop. We need to check the voltage at the thick positive cable right off the alternator. Then compare it to the voltage across the battery. If it is the same that alternator is most likely faulty. If there is a big difference we should replace the cables. Let me know.
Customer: replied 1 year ago.
the voltage is the same at the alternator. I got the old alternator checked today and it is definitely bad - so that was a good move. I will remove the second alternator and take it in for testing. Both alternators have a slip clutch pulley, but the new ones seem to have a solid pulley. Is it essential to have the slip clutch type?
Expert:  Richard replied 1 year ago.

I have not had good success with aftermarket alternators on these vehicles so I only use the Jag

Customer: replied 1 year ago.
Hi Richard, I took out the alternator #2 and had it tested at a local autotec - and they say it is in full working order - no issues with it. They ran it on a bench tester for an hour. So if the alternator is good but the battery light stays on and the voltage starts at 14V then drops to 12V after 10 min or so, and does this every time the car is started and run, then where else would the problem be. And what steps should I take next?