2001 Explorer Lights flickering when cold
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2001 Explorer Lights flickering when cold
Hello all, I recentlty changed a bad (not charging at all) alt on my wifes 01 Explorer. I get my alternators from a local shop that rebuilds them. After I put the rebuilt one one it was charging fine but I noticed in the morning when it first started and for a half hour or so the headlights and interior lights were flickering. After a while it settles down and is fine. I'm thinking the rebuilt alt I put on has a bad regulator. Hate to pull the thing off but looks like I might have to. Any thoughts? Thanks
Logistics Pro
Joined: Jun 2009
Posts: 4,820
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From: Cedar Rapids, IA
If you have access to a handheld oscilloscope, put the scope on the battery set for AC coupling. Check for any AC noise riding on the charging system. If there is more than a few millivolts of AC noise, then you probably have one or more bad rectifiers in the alternator.
If you don't have an o-scope, but have a good multimeter, set the meter to ACV and check again for AC on at the battery.
While under the hood, double check all the connections, making sure everything is plugged in fully between the battery, alternator, and battery junction box. Also make sure the connections at the battery are clean and tight.
If the shop you purchased the alternator from rebuilt the alternator on-site, I'd expect them to have the correct tools to properly check out the alternator and charging system. You might consider swinging by their shop, explain that you just purchased the alternator from them and you suspect it has an issue. They should be able to identify the most likely culprit before you go to the work to remove the alternator.
-Rod
If you don't have an o-scope, but have a good multimeter, set the meter to ACV and check again for AC on at the battery.
While under the hood, double check all the connections, making sure everything is plugged in fully between the battery, alternator, and battery junction box. Also make sure the connections at the battery are clean and tight.
If the shop you purchased the alternator from rebuilt the alternator on-site, I'd expect them to have the correct tools to properly check out the alternator and charging system. You might consider swinging by their shop, explain that you just purchased the alternator from them and you suspect it has an issue. They should be able to identify the most likely culprit before you go to the work to remove the alternator.
-Rod
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I do have a o-scope 465B. I really suspect the regulator. I have a year warranty on it but its a pain to pull it and drive the 30 miles to the place I got it from. From what I can tell, in the morning after sitting all night the charge on the battery has dropped and when starting the Voltage fluctuates till the battery reaches full charge. It charges fine but the lights flickering is more of a anoyance than anything else.
Logistics Pro
Joined: Jun 2009
Posts: 4,820
Likes: 83
From: Cedar Rapids, IA
The scope should help you identify the cause of the flickering. The flickering could be due to AC on the charging system, or if it is truly a pulse or drop of the DC you can DC couple the scope and set a trigger point to trigger if the DC drops below or rises above the trigger point. Some scopes have a glitch detect mode as well. If your "465B" is a Tektronix 465B, that won't be very easy to drive around with though, and probably doesn't have a glitch detect mode.
If the issue is a shift in the DC voltage you need to confirm the integrity of your connections though before condemning the regulator.
-Rod
If the issue is a shift in the DC voltage you need to confirm the integrity of your connections though before condemning the regulator.
-Rod
Logistics Pro
Joined: Jun 2009
Posts: 4,820
Likes: 83
From: Cedar Rapids, IA
Thanks, and Happy New Year to you as well.
You might call the place where you got the alternator to find out if they can fully test the alternator while on the vehicle. It would be a real bummer to pull it and have them bench test it only to say all is well with it. That's where knowing if there is AC on the charging system would help justify you questioning the alternator.
Also, if you'd like a schematic of the charging system from the factory service manual, send me a Private Message with the request and an e-mail address for you and I'll e-mail a PDF of the diagram.
-Rod
You might call the place where you got the alternator to find out if they can fully test the alternator while on the vehicle. It would be a real bummer to pull it and have them bench test it only to say all is well with it. That's where knowing if there is AC on the charging system would help justify you questioning the alternator.
Also, if you'd like a schematic of the charging system from the factory service manual, send me a Private Message with the request and an e-mail address for you and I'll e-mail a PDF of the diagram.
-Rod
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