FLICKERING LIGHTS

Tiny
NICK WADE WILLIAMS
  • MEMBER
  • 1998 MITSUBISHI MONTERO
  • 3.0L
  • V6
  • 254,000 MILES
Hello, I have had this vehicle since March 20th of this year, bought it in pristine condition. I have never had any problems with it until about a month ago, while driving, all electrical as well as the "speed" of the car, I noticed to quickly slowed down. Radio cut off, my interior lights shut off, and the car would not go any faster than ten mph. After I got home, it would not crank back up. So I had a brand new alternator installed, as well as a new battery. New alternator and battery were both just put in about a week or so ago (8/23/2016). Since then, it has been running great as new. Now, for two days, while I am driving, or even if it is just idling ; The car's interior and exterior lights flicker/pulsate nonstop! I have been told that the voltage regulator, whatever that is, needs to be replaced. But I am not sure. I do not have the money currently to even have it tested. As a matter of fact; Advanced Auto Parts, Auto Zone, O' Rieillys, etc; All tell me they cannot do any type of testing unless the engine light is on. The engine light has never came on since I have had the car. Only the alternator and battery light, but they no longer are a problem. Please help me! I am not sure what causes a car's interior and exterior lights to "Flash/Pulsate/Flicker", nonstop. Thank you.
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Thursday, September 1st, 2016 AT 7:03 PM

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Tiny
NICK WADE WILLIAMS
  • MEMBER
Sorry for the inconvenience, I forgot to mention my email. It is :
Williamsnick461@gmail. Com
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Thursday, September 1st, 2016 AT 7:04 PM
Tiny
CARADIODOC
  • EXPERT
You are the victim of some misinformation. The people at the auto parts stores are not mechanics. They understand selling stuff that is often not needed. The testing they are referring to with the Check Engine light has to do with diagnostic fault codes that can be stored in the Engine Computer when it detects a problem. They will read those codes for you for free, but you must understand there are well over 2,000 potential fault codes, and only half of them will cause the Check Engine light to turn on. Those are the ones related to something that could adversely affect emissions. That means there can be one of more than a thousand codes stored when the Check Engine light is not on. It is not correct to say the Check Engine light has to be on to check for fault codes.

The next issue is you need the charging system tested. That usually has nothing to do with the Check Engine light and fault codes. A charging system problem can result in the Engine Computer detecting a problem related to low system voltage, and that can set a fault code, but it is still the charging system that has the defect.

Most auto parts stores have generator and starter test benches, but those are by far the least desirable way to test those items. Starters need to be tested under load while trying to crank an engine. Generators need around five horsepower to spin them under full load, and no test bench has a motor big enough to do that. Testing generators on the car includes all the related circuitry in the tests. The circuitry is responsible for just as many problems as the generator itself.

Your voltage regulator is built into the generator so you got a new one when you bought the replacement generator. The issue here is a defective voltage regulator almost always causes a total failure to charge, or an over-charge condition, and both problems are rarely intermittent. The flickering you described is usually the result of the voltage regulator responding to something that is causing rapidly rising and falling system voltage, and that is not going to show up on charging system tests. For this type of problem you need to try various solutions while the engine is running and the problem is occurring.

I should back up a minute and suggest you have the charging system load tested by your mechanic. We need to see the results of the "full-load output current test". During that test, which only lasts a few seconds, the generator will develop its maximum rated current or exactly one third of that. A typical generator for a '98 model might be a 90-amp unit. If all you can get is 30 amp's from it, there is a failed diode inside it. 30 amp's is not enough to run the entire electrical system under all conditions. The battery will have to make up the difference until it slowly runs down over days or weeks. More importantly, the output voltage will be bouncing up and down a lot, and the voltage regulator will react to those "dropouts". The result you might see is flickering lights.

If the output test is okay, look for ground wires with loose or rusty connections. One of them goes from the battery negative cable to the body sheet metal. On some engines there is another one between the generator and the engine block.
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Thursday, September 1st, 2016 AT 8:48 PM
Tiny
CJ MEDEVAC
  • EXPERT
This could be an alternator or voltage regulator (now a days, this is a part of the alternator)

Yep, even new stuff can be bad! (seen this many times!)

Case in point, I just helped my pal install a crated six cylinder engine in his 1980 Jeep CJ-5. New everything on the engine, barely would run, spitting back through the carburetor. Found that a brand new spark plug was not firing. Found this after hours of searching for the problem, my worrisome pal is now nearly bald from pulling his hair out!

Your parts should be still under warranty

Have the battery/charging system tested tested where you purchased them (not the engine codes)

It may be that both are fine, however, there might be a disruption between the alternator and battery (the charging wont reach the battery) This might be a fuse/ broken wire/ loose connection/ or a fried fusible link.

You may be able to diagnose if this is the case yourself!

At the top of our page is "REPAIR GUIDES", This link is from the "Electrical" section

https://www.2carpros.com/articles/how-to-check-a-car-alternator

You can get a decent and cheap voltmeter from "Harbor Freight" for about $5, auto stores may have 'em for around $20.00. They are great to use for other issues you may have in the future!

Keep us posted on your progress, or if you need more information, keep responding.

The Medic

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Thursday, September 1st, 2016 AT 8:57 PM

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