Headlamps and Interior lamps Flicker (lerner@ka.net)

It's a 1995 Mark VIII. They flicker fairly fast at idle and faster with acceleration. Everything else seems normal. The battery and alternator are just a few months old. Someone told me it sounds like a ground
problem. I hope it's not the alternator even though it's under warranty and I put it on. It didn't do this before the battery and alternator and it didn't do it after. It started about a Week ago. Seems to run perfect and smooth. Thanks for your help.
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snipped-for-privacy@ka.net wrote:

It's a loose connection somewhere in the lighting circuits. I'd look at the circuit common to those lights.
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snipped-for-privacy@ka.net wrote:

Maybe ground, but could still be alternator. The stock Mitsubishi 120A alternators seem to be impossible to rebuild reliably. The best bet for an alternator is a Ford/Motorcraft 2nd Generation one (Delco design) made for a late '96 thru the '98 Mark VIII. Perfect fit, very reliable, and 10 more amps capacity than the older model. Another reliable way to go on the Mark VIII alternator is to buy an aftermarket NEW alternator from a place like PA Performance or WAI. Another thing that can go bad is the 3-wire IAR plug that plugs into the back of the alternator, about $8 at any auto parts store. The electrical warning system on a Mark VIII is not very good, and a $15 plug-in voltmeter (equus 3721) from Wal-Mart will allow continuous monitoring of the charging system.
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Sharon Cooke wrote:

I will check all this out. For what it's worth the alternator is new and not rebuilt. It's from Autozone but I had the option of a rebuilt or a new one and I got the new. I realize it could still be bad.
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snipped-for-privacy@ka.net wrote:

I think I might know why the lights flicker but haven't checked. A few years ago I replaced the turn signal control that also operates the brights. I replaced it because my headlights wouldn't work at all. It had a wiring harness that plugged in the unit. At that time the plug on the harness looked as if it had gotten hot. So if thats it I don't think it will be easy to replace that plug with so many wires in it.
The alternator and battery tested good.
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snipped-for-privacy@ka.net says...

Sometimes with the right tool the pins of the plug can be removed and put into a new plug after the bad ones are fixed. Not all plugs will do that however.
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I. Care
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I. Care wrote:

Thanks, I'm envisioning me doing that and it's not a pretty site.
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snipped-for-privacy@ka.net wrote: ( 1995 Mark VIII )
Headlamps and interior lamps flicker fairly fast at idle and faster with acceleration. The battery and alternator are just a few months old, and they both test good. ____________________________________________
Check for a failing voltage regulator.
Sometimes flickering is caused by poor brush/slip ring contact in an alternator, but yours tested okay.
Good luck.
Rodan.
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Rodan wrote:

I noticed I have a tail light out. I will replace that tomorrow. You never know with these crazy cars.
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snipped-for-privacy@ka.net wrote:

Once again, did you replace that 3-wire pigtail that plugs into the back of the alternator? A cracked connector/corroded wires can cause that exact same condition of flickering lights.
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Sharon Cooke wrote:

I inspected that today. I only unplugged it and plugged it back in. Looking at the connector it looks new. No corroded wires there.
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snipped-for-privacy@ka.net wrote:

I did a lot today without success. I removed all the chassis grounds I could find and sanded the chassis to a shiny metal and sanded the terminal ends and put them back on tight. I found chassis grounds for the negative battery cable, the one at the starter, I found two that were tied into the lighting under the hood. When I turn my headlights on my interior lights and all the dash lights drastically dim. I'm still wondering about a faulty battery. In June when I put on the new alternator I ran the battery all the way down. My friend charged my battery before we started the car with the new alternator. At that time in June he could charge my battery up as high as it should have been. The battery still works but it might be crippled. I appreciate everything you all are suggesting and I will try everything. Probably not much more you all can do. Thanks
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snipped-for-privacy@ka.net wrote:

Also the battery post was sizzling a little when I turned the engine off. A little water may have come out from under the caps.
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On 10 Nov 2006 12:02:08 -0800, snipped-for-privacy@ka.net wrote:

I would strongly suspect you have a bad battery connection, but in order to find out for sure what your problem is you need a voltmeter and you need to understand how to perform voltage drop tests on bothe the power and ground sides of the circuit. That is the ONLY way to pin it down accurately - as well as the simplest.
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clare wrote:

Just wondering, when you turn the interior lights off with the dash switch is that supposed to lock the doors? It's doing it on my car and seems strange.

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snipped-for-privacy@ka.net wrote:

you first step is to clean the battery cables and tighten all the grounds you can find under the hood. Also check your connections at the alt. My guess would be a bad alt. Look for pulsing voltage on the bench when you take it back. If you can see the lights pulse you should be able to see the voltmeter on the tester pulse.....but not necessarily :)Either way talk them into replacing it. (only way you will know for sure.)
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