Dash lights & headlights increasing/decreasing in intensity?? - JKowners.com : Jeep Wrangler JK Forum
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post #1 of 4 Old 11-19-2018, 03:15 AM Thread Starter
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Dash lights & headlights increasing/decreasing in intensity??

Greetings all,
I have the following issue with my Jeep Wrangler JK 2011 3.8l. I noticed afther driving steady for awhile and idle ( 30 min) my dashboard, consol, rooflight, and headlights, intensify and dim irradically,
Out of control, does anyone know what can cause this? No Codes coming up on dadsboard and ODBII. No engine light warnings. Your help would be highly apreciated. Regards and thanks in advance. Edbergh.
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post #2 of 4 Old 11-19-2018, 07:00 AM
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After the engine has been off for awhile, and before you start it, note the battery voltage.
Start the engine and note the battery voltage again.

When you see the light intensities going up and down, note the battery voltage again, and see if the readings go up and down, too. An analog meter is best for seeing variations in the values.

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Last edited by ronjenx; 11-19-2018 at 08:48 AM.
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post #3 of 4 Old 11-20-2018, 11:13 AM Thread Starter
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Hi ronjenx,

Thanks for reply, i have done what you told me here is the result below;
1. Before starting - 12.2 V 1 min.
2.-start idling, all electrical off.13.4- 13.8v
Duration 4 min.
All lights, radio , A/C on 13.4 to 13.6 V.
Duration. 2 min.
3.-engine off, 12.7- 12.5 duration 1 min.
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post #4 of 4 Old 11-20-2018, 12:33 PM
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Quote:
Originally Posted by Edbergh View Post
Hi ronjenx,

Thanks for reply, i have done what you told me here is the result below;
1. Before starting - 12.2 V 1 min.
2.-start idling, all electrical off.13.4- 13.8v
Duration 4 min.
All lights, radio , A/C on 13.4 to 13.6 V.
Duration. 2 min.
3.-engine off, 12.7- 12.5 duration 1 min.
1. Should be 12.6 V or more.
2. Should be about 14.3 V.
3. Should be 13+ V, and not drop below 12.6 for weeks.

Could be a bad battery.
Could be a bad alternator, which can cause a battery to go bad.

How old is the battery? Have the terminals ever been cleaned and checked for tightness? Inspect the wire between the alternator and the battery + terminal.

I would give the battery a good charge. See if it takes and holds the charge. If it does, have it load tested.

If the battery checks "good", charge it again, then install it and see how the alternator behaves. The alternator should maintain about 14.3 V.

If the battery checks 'bad", install a new one and see how the alternator behaves. The alternator should maintain about 14.3 V.

If the alternator shows low voltage, have it checked. Don't let it go too long, as it can bring down a good battery.
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