• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Help with grinding noise and dimming lights

Wanna XJ

NAXJA Forum User
Location
NWGA
Trying to help my nephew out again. Cleaned out the ICV last week. As he was leaving he said hey, here's that noise its been making. Kids!! Anyway, I gave it a listen, it sounded like it was from underneath the 01 XJ about mid section or further back. I just figured it was a loose shield or something and blew it off.

Now today he just casually mentions that the lights dim and the radio looses settings when the grinding/rattling noise happens. That ain't good!. Any ideas why a grinding/rattling noise from underneath the car would have anything at all to do with lights or electrical system issues? I have no idea where to start on this one. Could it be a short on a transmission or Tcase pump or something or maybe fuel pump?

Thanks as always for your help. I have found this to be one of the friendlier forums. Very few wise guys and a lot of useful and helpful input. Keep up the good work.
 
x2 on the alt. he can either take it out and take it to autozone or the like and they can bench test it or he can drive it there and they can test the charging system while it's running.
 
The noise isn't coming from the engine compartment. See original post for clarification. And, it only does it for a little while and then quits until next time.
 
Does the noise happen frequently, randomly, just when cranking? Devil is in the details. Noises are tricky to isolate and tough for us to help you with. Gotta put your time to find root cause.

If the lights dim and radio loses it's presets, that is a clue that this is electrically based and the usual suspects are located under the hood. If you're certain that it's further back, then I'd try to get the XJ on a hoist and get under it and see if you can recreate it to help you find it.

If you can recreate it, you should be able to find it.
 
My '00 makes a rattling noise underneath sometimes when it is warming up cold, and then it goes away. It might just rattle when it runs real slow, which could also make the voltage drop off. The voltage dropping off might make it run rough.

Check battery voltage with a voltmeter. Should be above 14V when running. Have the spark plugs ever been changed? A cylinder could be dropping out, making the idle rough and slower. Seems like that would trip the CEL pretty quickly.
 
Here's a thought. The next time you're under there check the catalitic converter. The heat shields are spot welded together and frequently rust. It will make a racket like you described. I just clamped my two halves together and ran some self-tapping screws through the lips and the noise stopped completely. This obviously wouldn't create an elctrical problem, but it wouldn't be the first time two unrelated issues started at the same time.

Any time I'm working on DC voltage the first thing I do is clean/apply dielectric grease and retighten every ground connection I can find.

If you can recreate the lights dimming, throw a voltmeter across the battery terminals if the alternator is putting out the proper voltage it should read about 14 volts and check the voltmeter gauge on the dash. If the alternator stops putting out you should get a "Check Gauges" light on the dash and it will read zero. The headlights dimming could mean that they're running off the battery (12.6 volts) and will be dimmer than the ~13.8 volts while the engine is running.
 
Back
Top