Dimming and flickering problem

1994mustangcobra

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I have a 1994 Mustang cobra. The cluster lights including the rest of the lights tend to Flicker. The battery gauge goes below half especially when I turn the lights on and apply the brake lights. I am a very observant person so if you know the noise of the fuel pump in the back I can hear the tone of the fuel pump noise go with the flickering and dimming like loss of power or shortage. I already took it to the mechanic they replace the battery terminals and it still doing the same shit and the battery and alternator is fine. I’ve been doing some research and found out that it might be the fuse link leading from alternator to fuse box. American muscle has it for sale for 50 bucks. I don’t want to purchase it and replace it for nothing. Has anybody ever encountered this problem and resolve the situation please let me know thank you.
 

mrmustang

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I have a 1994 Mustang cobra. The cluster lights including the rest of the lights tend to Flicker. The battery gauge goes below half especially when I turn the lights on and apply the brake lights. I am a very observant person so if you know the noise of the fuel pump in the back I can hear the tone of the fuel pump noise go with the flickering and dimming like loss of power or shortage. I already took it to the mechanic they replace the battery terminals and it still doing the same shit and the battery and alternator is fine. I’ve been doing some research and found out that it might be the fuse link leading from alternator to fuse box. American muscle has it for sale for 50 bucks. I don’t want to purchase it and replace it for nothing. Has anybody ever encountered this problem and resolve the situation please let me know thank you.

Check your grounds
Check your battery cables themselves
May be your voltage regulator
Might even be your headlight switch
Who tested the alternator and the battery?

Take it to a better shop if you cannot figure it out yourself.

Finally, don't be afraid to spend a little money to find out what the issue actually is. Doing so up front will save you more in the long run
 

1994mustangcobra

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Check your grounds
Check your battery cables themselves
May be your voltage regulator
Might even be your headlight switch
Who tested the alternator and the battery?

Take it to a better shop if you cannot figure it out yourself.

Finally, don't be afraid to spend a little money to find out what the issue actually is. Doing so up front will save you more in the long run
 

1994mustangcobra

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I bought a new battery and i did a alternator test my self, if it was the alternator it would shut off while running when I disconnected the negative battery and it didn’t. So alternator is fine. I also installed new battery terminals. The shop I took it too did a voltage drainage test and said they can’t find anything. They already charged me 2300 to replace the rear main seal and one of the gears in the rear end differential. I guess I’ll take it to another shop then thanks.
 

1994mustangcobra

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Does it have aftermarket pulleys? When I had underdrives on my 95 street Cobra the lights would dim at idle.

Tom
The only pulley I changed was the idler pulley but it was doing all that before then I figured I change the idler pulley when I replaced the radiator and serpentine belt.
 

98 svt

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1 thread would be sufficient.
You asked this question in 3 threads, including starting 2 new ones
 

98 svt

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I bought a new battery and i did a alternator test my self, if it was the alternator it would shut off while running when I disconnected the negative battery and it didn’t. So alternator is fine. I also installed new battery terminals. The shop I took it too did a voltage drainage test and said they can’t find anything. They already charged me 2300 to replace the rear main seal and one of the gears in the rear end differential. I guess I’ll take it to another shop then thanks.


Did you physically test the alternator with a multimeter?
 

scottydsntknow

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Did you physically test the alternator with a multimeter?


The alternator can be bad and still charge the battery and have stuff work and have all the symptoms you listed. TBTH I'm amazed you haven't just done the alternator yet. I'm going to bet that is your issue. Test it with a multimeter like in the video or just go ahead and replace it.
 

1994mustangcobra

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The alternator can be bad and still charge the battery and have stuff work and have all the symptoms you listed. TBTH I'm amazed you haven't just done the alternator yet. I'm going to bet that is your issue. Test it with a multimeter like in the video or just go ahead and replace it.
 

1994mustangcobra

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Why not TEST yours first, instead of just throwing money at it? Takes less than 1 minute.
True but honestly, might sound dumb. To me it looks old anyways and my engine bay is clean af. Might as well just replace it. I should of replaced it when I did the radiator and serpentine belt. What’s a good watt alternator I should get? 200?
 

railroad

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Just a shot in the dark, but sometimes a lack of, or poor ground will create issues. Try putting a jumper from the battery ground to the engine block. You can do this with a jumper cable or make up something with terminal ends or alligator clips. It does not hurt to jumper over to the frame also. Hope this helps.
 

1994mustangcobra

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Ok so finally had a chance to change the alternator, and still doing same thing. I take it to another mechanic. He spends hours on it to figure why it’s dimming/flickering then finally calls me and tells me who ever had this before me changed the crankshaft pully to make the car idle faster and he said sometimes people do that. So then I told Him ok well can you change that? The. He says now your dealing with hot rod shit I don’t want to waste my time doing my research and said for me to do my research and once I figure what size it is he said he can install it....... smfh
 

1994mustangcobra

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Ok so finally had a chance to change the alternator, and still doing same thing. I take it to another mechanic. He spends hours on it to figure why it’s dimming/flickering then finally calls me and tells me who ever had this before me changed the crankshaft pully to make the car idle faster and he said sometimes people do that. So then I told Him ok well can you change that? The. He says now your dealing with hot rod shit I don’t want to waste my time doing my research and said for me to do my research and once I figure what size it is he said he can install it....... smfh
Just a shot in the dark, but sometimes a lack of, or poor ground will create issues. Try putting a jumper from the battery ground to the engine block. You can do this with a jumper cable or make up something with terminal ends or alligator clips. It does not hurt to jumper over to the frame also. Hope this helps.
 

jman37

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Sounds like you have under drive pulley's installed. I personally never run them because I don't buy into them so I can't say for sure that's the real reason you're experiencing those issues. I'd personally do what has been said and check/clean your grounds.
 

1994mustangcobra

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No sho
Sounds like you have under drive pulley's installed. I personally never run them because I don't buy into them so I can't say for sure that's the real reason you're experiencing those issues. I'd personally do what has been said and check/clean your grounds.
what if I change the alternator pulley to a lighter one like BBK. You think that will work? I don’t understand why the mechanic shop couldn’t figure it out. I’m not good with electrical and looking for all the grounds. This is the second shop that couldn’t figure out what exactly the problem is and telling me I have about 4 aftermarket pulleys. But what I don’t get whoever had this before me, why they didn’t change the alternator pulley as well. I mean I changed out the serpentine belt and tensioner pulley when replacing the radiator and the serpentine belt is the same size. I didn’t have to get a special belt. I guess I’ll have to wait until ford dealership opens up so i take my car there and see what they can do. Seems like non of these shops can’t figure this out. At least the battery is not draining anymore that’s a good thing. It runs beautiful just the dimming part is the annoying part when idling.
 

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