Flickering headlights and dash lights
Printed From: West Coast Fieros
Category: Technical Topics Forum
Forum Name: Technical Questions and Discussions
Forum Description: Got a technical question about your fiero? ask it here.
URL: http://www.westcoastfieros.com/forum/forum_posts.asp?TID=3058
Printed Date: 22 November 2024 at 4:50pm
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Topic: Flickering headlights and dash lights
Posted By: Boxin' Robin
Subject: Flickering headlights and dash lights
Date Posted: 10 October 2012 at 11:08am
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Need help diagnosing this symptom please... I replaced the alternator on my 86 GT about a month ago. Was told by the mechanic that the battery will also need to be replaced sometime in the near future. Shortly after, I began to notice that the headlights and the dashboard lights would constantly dim and brighten as the engine is running. Is this the symptom of bad alternator or bad battery? Also, what is the volt meter suppose to display? Mine shows 16V at start-up and only drops to about 15V after driving for a while. Thank you for any advice/suggestion! |
Replies:
Posted By: ARTIC-1
Date Posted: 10 October 2012 at 5:54pm
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Sounds like you still have a problm! Do "load" test on the two main feeds{big red wires with Fuses inline} to the car.At the power block in the engine bay.dim and brighten as the engine is running dosent sound good,bad ground! some where-Check all Grounds-your Fieros alternator should be 14.4V,-16v is a bit Hi.all so another easy way is to pull ALL the fuses out of the fuse box-turn key on-an use a 15Amp multy meter on the -Load setting an check every fuse sockets load. you might get lucky! an find the Bad one.then you will no witch circuit to fix.there are other people here that have a lot moor experience with this,an may have the Fix,some one else should post to. good luck. ------------- SNOW MAN 87-GT/AUTO-2.8_ WHITE 88-TTop/ Duke-2.5. RED |
Posted By: Boxin' Robin
Date Posted: 11 October 2012 at 12:38am
Thanks Snow Man for the response  . I'm just curious
about one thing... if the battery is old and dying, would the alternator be overcharging it to try to "overcompensate" for the lack of charge? By the way, you are out near Harrison Hot Springs, right? I saw a white GT with rear wing driven near Minter Gardens on Sunday. Was that you? |
Posted By: CFoss
Date Posted: 11 October 2012 at 4:56pm
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The symptom COULD be caused by a battery with an intermittent partial short circuit. I'd swap it with a known good battery asap. When it shorts out the altenator can't support full voltage in the car. It could also be a repedative high resistance short elsewhere, OR belt slippage. check belt tension for sure. Chay ------------- 86 SE 3.4 |
Posted By: ARTIC-1
Date Posted: 11 October 2012 at 5:12pm
Yea that was me,an it was true Bliss that day.and a old battery might do that.like Chay said-The symptom COULD be caused by a battery with an intermittent partial short circuit.get a new battery an see how it goes.if its still is wacky after the new battery you will have to find out just what it is,if i were closer i would help out around here a little more. ------------- SNOW MAN 87-GT/AUTO-2.8_ WHITE 88-TTop/ Duke-2.5. RED |
Posted By: ARTIC-1
Date Posted: 11 October 2012 at 6:10pm
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Fluke This is the Type of Multy meter with a fork at the end Easy to use-to check Load on any wire-AC or DC just stick the wire in between the fork an it tells you the load-10 amps-40A- up to 600 with this meter. an its a regular meter with probes ends. check the two big red 10 gauge wires that are in the Eng/bay when its running doing that surge thing! should take about 5 or 10 min to track down a bad circuit with this typ of meter.  ------------- SNOW MAN 87-GT/AUTO-2.8_ WHITE 88-TTop/ Duke-2.5. RED |
Posted By: CFoss
Date Posted: 11 October 2012 at 8:30pm
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I have that meter as a backup...it has some limitations. I'm pretty sure it's only an ac ammeter, and the voltage resolution is only units (IE: 10v, 11V, 12V etc). It's meant for a house wireman, but no the best for automotive. Flule does have some good stuff though, I use the 87V, but it's way expensive. A 167 is a pretty good general puropse meter, but doesn't have the current jaw. DC clip-on current devices usually takes a more expensive measurement device because of the technique required to measure it properly. We use 'add-on' current to voltage converters for this. Chay ------------- 86 SE 3.4 |
Posted By: Boxin' Robin
Date Posted: 12 October 2012 at 9:13am
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Thanks to all who responded. Unfortunately, I'm not much of a handy guy around cars (LOL why the heck did I get a Fiero, eh?). Called BCAA to take a look, as I have only used one call in the past year. The technician spent about 30 minutes running tests etc. Apparently, the battery is "okay". He said it might be the voltage regulator in the alternator. So I will take the car back to the mechanic who installed the alternator a month ago and get everything checked out. On another note, when the battery was removed last night, we found that the whole battery tray / holder is almost completely rusted. Seems VERY unsafe to me. Is this something I can buy at Lordco and replace? Or is it a Fiero-specific thing? Thanks guys! |
Posted By: CFoss
Date Posted: 12 October 2012 at 6:04pm
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Well, you'll probably get to be handy, or get to be broke really quick! Just saying, the Fiero can be a money pit, even for someone with good skills. To check the belt tension is really easy. Press on it. If it deflects more than about 1/4 to 1/2 inch it is too loose! The battery tray...not sure because I made my own. I think they are welded in and the remnants will need to be cut out/grinded out, then a new one intalled. I'm not sure where you would source one to be honest. Chay ------------- 86 SE 3.4 |
Posted By: beken
Date Posted: 22 October 2012 at 10:21am
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At idle, if you have your headlights on, heater, wipers, stereo blasting, it will be very difficult for a stock alternator to keep up with the current drain. If you battery is not fully charged, you will get some dimming as your car is drawing power away from both the alternator and the battery.
You can try to desulphate the battery and then a full recharge of your battery. I do that once a year. I have a CTEK battery charger that does just that. The BCAA guy will just check to see that you are getting the right voltage out of the battery. If your battery is getting old, it might not be holding enough current to power both your headlights and all your fall/winter ancilliaries. A desulphate can sometimes help. The $40 battery in my Fiero is about 8 years old now and still going strong. My MINI is 7 years old and still on its original factory battery. Also, I have experience that getting an alternator from Canadian Tire is not the best place to get one. A previous car (Plymouth) had the wrong alternator put in. -------------  Beken (aka Ken) - bekentech@westcoastfieros.com Original and still the owner of an 85SE 2M6 4spd |
Posted By: Boxin' Robin
Date Posted: 23 October 2012 at 8:08am
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Thanks Ken, Chay, Snow Man for trying to help. I've finally had enough with these little problems over the past 2.5 years. Just went out and bought myself a new 2012 Civic Si. Having paid off my wife's car a few months ago (after 5 years) also helped make the decision easier - at least financially anyway. I will unfortunately have to let the Fiero go. The alternator and the battery have just been replaced a week ago. EVERYTHING works perfectly fine in this car, except the emergency brake. Please help pass on the words; I want it to go to a good home rather than a junk yard |
Posted By: CFoss
Date Posted: 23 October 2012 at 8:21am
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Nothing wrong with that. Fieros can be difficult at times. That's why they're usually priced kinda cheap for what they are. Hope it sells for you. Chay ------------- 86 SE 3.4 |