[tsuintx]

I recently came into possession of a 2003 XG350 w/194K miles. When I got it, the battery was dead as a doornail: less than 9V with the car off and didn’t take a charge. I barely got it running with a jumper box, but the battery still showed less than 10V and the battery light was on.

Bought a new battery and alternator. Talk about a bitch of a job to change that friggin’ alternator, but I guess that’s a topic for another thread/discussion...

Anyway... Went for a drive, but after a few miles the battery light came on again. It goes out when revs are above 3000 either while driving or standing still. Light on and the car idling, multimeter only shows 12.6V from the terminals, so clearly it’s not charging.

So... Any suggestions as to the next course of action? Battery terminals are secure, battery cable to the back of the alternator is secure, connector to the alternator is secure and serpentine belt is tight. That should all be it, right? Even checked the fuse next to the positive terminal of the battery and at least it looks good.

What else to check? Kinda getting stumped here, so any and all suggestions are appreciated. Even any simple things you could think of I might be missing. Just don’t really want to kill the new battery.

 

[avisitor]

Would first start by cleaning the battery terminals
Then, clean the ground strap and chassis from the negative battery post
Then, clean engine grounding strap .. both at the engine and the chassis

With connections restored somewhat, ...
Start engine and measure voltage across the battery
Measure voltage from alternator to ground/battery negative
Hopefully things return to normal

If not then look at this for more ideas ...

Good luck

 

[tsuintx]

Thanks!

I did clean the battery terminals when I replaced the battery, so those should be pretty clean.

Any idea where the ground straps are located at? Looked around in the FSM I found online and so far I haven’t found a chart or picture showing them. Otherwise I guess I’ll just have to dive in and find them somehow.

 

[tsuintx]

Replaced the 140A fuse at the positive battery terminal to no avail. Also made sure both terminals are clean and they are. Checked all ground straps I was able to see at the top of the engine bay and they all seem fine.


Guess there's still a strap somewhere from the block to the chassis underneath, so need get it on ramps to do further investigation. Still haven't found any pointers online as to where it might be.


Car idling the battery shows 12.3x measured across the posts. It also measures the same between the alternator and ground/negative terminal.


I really want to hope the new (rebuilt) alternator is not the culprit as it is such a bitch to remove. But I guess if all else fails, I need to take it out and have it tested and potentially replaced. I'll probably be able to get it out much faster second time around.

 

[AUTOSPARK]

I wouldn't waste too much time looking for that ground strap. If the engine block ground was that bad that it couldn't carry the alternator charging current, it wouldn't be able to carry the much higher starter motor current either, and the engine wouldn't crank.

 

[avisitor]

Alternator is not putting out correct charging voltage.
Would suspect alternator. Need to test.

 

[tsuintx]

That’s the direction I’m leaning towards. Unfortunately... If it wasn’t such a pain to R&R, I probably wouldn’t have looked for other things first, but I guess it looks like I’ll be taking it out again and get it tested. There’s actually a small shop in town that rebuilds starters and alternators and they have tested some for me in the past and have come up with different results than the auto parts stores, so I’ll probably take it there first.

If it tests good, things will get even more interesting...

 

[tsuintx]

Yup, had the alternator tested at the alternator/starter shop and it was dead as a doornail. Swapped it for another and had Advanced Auto as well as the shop test it and it was good to go.

Put it back on and no more battery light. All the work as well as trip to test and swap the bad one in less than half the time it took the first time around just to R&R. LOL!!! It’s actually pretty straightforward job when you’ve done it already.

Now I just have the next problem: idles fine for a while and then just dies. Same happens when you coast to a stop etc. Never a dull moment...

 

[avisitor]

Congrats on fixing the alternator problem.
Thanks for the update

 

[tsuintx]

Thanks. I like to always bring my threads to a close once the issue is resolved. Too many open-ended threads out there all around.

And it looks like the stalling/idle issue took care of itself, too. The ECU probably just needed some time to relearn the running stuff after disconnecting the battery.