At my wits end! Flickering lights and voltage gauge!

[91explorer1009]

I have tried everything I could think of, searching this forum forever and plugging in parts like an idiot! I will try to keep this as short and to the point as possible.

I have had a flickering/surging voltage gauge in my 91 ex. along with surging/dimming headlights for a while now. First the starter went, so thats new. Then I replaced the Alternator with a brand new not reman. one. Next I put a new battery in, and finally this week, brand new OEM battery cables. I thought the cables would do it since mine were all corroded and green and I have put new heads on twice in the past. New positive and ground!

Now its usually when I start the truck up after its cold, I get a flickering batt. gauge, along with surging dimming headlights. After I drive it around and it warms up after about 5 mins or less the gauge stops bouncing and theres no more dimming, all is well!?!? The needle is steady right between the R and M, right in the middle.

Please guys I am done, tired of trying...ready to go get a new truck. Any more ideas??? Thank you.

 

[Tbars4]

....Just my thoughts but you may have a parasitic draw such as stereo, alarm, a bad fuel relay, etc...It also may be the alternator wiring...

...This is based on the first start of the morning theory as you explained...Either you have something depleting your battery overnight or your alternator wiring is weak or shorted...

...When you start your engine when it's a cold start, you have a significant draw plus you are running your lights...The bouncing gauge and flickering lights are saying low voltage....Your alternator kicks in to replenish the voltage, this is why you see less dimming...

...I would go out in the a.m. and test your battery voltage across the post before you start it...It shouldn't be less than say 12.5 volts...:scratch:

...It is not uncommon to get a bad battery or alternator when new either...You can have them bench tested for free...Just don't trust the crash cart test...

 

[my pos mounty]

...I would go out in the a.m. and test your battery voltage across the post before you start it...It shouldn't be less than say 12.5 volts...:scratch:

I thought that voltage should be higher, somewhere closer to 13.6 or so?

 

[Tbars4]

...It will be 14 or so while charging and 13.6 overnite would be great considering it's a new battery...

...My thoughts are if he has a parasitic drain of some sort, the 12.5 would be still tolerable for a new battery of a lessor quality...I have a feeling he will find a lot lower voltage in the morning test due to either a parasitic drain or a bad battery that won't hold a charge...

...Another test while you have the voltage meter out and if that is not the case...Test across the post while someone starts the vehicle and see how low the voltage drops....If the battery is good, it will not drop below 10 volts....Again, this is based on all the new parts and everything else in working condition...

 

[91explorer1009]

Well I just replaced the fuel pump relay, the eec relay, there working well, no more whirring after shut off...

As far as parasitic draw...no alarm, nothing big...

I recently had it tested at autozone and it was putting out full/normal for both the battery before startup and the alternator was good too started up?

Is this fairly normal? Do other peoples trucks do this when they start up? I dont want it to mean the alternator is going out and im gonna get stuck somewhere...

 

[Tbars4]

Well I just replaced the fuel pump relay, the eec relay, there working well, no more whirring after shut off...

...When did you replace this???

...and we will be waiting to hear your voltage test results...

 

[91explorer1009]

I replaced the relays about a week ago.

 

[Reejerey]

if a car battery holds 13.6 volts overnight something is wrong. each cell of a car's lead acid battery is 2.1 volts if everything is working properly, or a total of 12.6 volts. It does sound like a possible parasitic draw issue, however. One quick test for a draw would be to disconnect the battery for overnight and see if you still have flickering lights ect. in the morning after reconnecting the battery and starting. That is if you don't have a good DVOM.

As far as Voltages, i'd look for 13.5 or higher at idle, and should stay close to that with headlights and rear defroster on (rear defrosters pull as much or more current than head lights). 12.5 with key off, and no lower than 9.6 when cranking to start.

To perform a parasitic draw test you need a decent DVOM capable of handling at least 10 amps DC. Make sure all accessories are off, key is off, doors are closed. Disconnect the negative battery cable and hook up the meter in series, with the red lead on the negative terminal and the black lead on the negative post. Walk away for 10-15 minutes to allow the computers to go back to sleep. When you come back you should see a draw of less than .050 A (50 mA), preferably around .015 (15 mA). If you see a draw higher than this, start pulling fuses from the fuse boxes while watching the DVOM. When you pull a fuse and the draw drops down to an acceptable level, thats the circuit you have a draw in. Further diagnostics will be required to find the draw, typically tracing down wires and componets of the circuit until you find the one that is causing your issues.


Edit: if you don't want to wait 10-15 min for the computers to go back to sleep, do this test after the vehicle has sat for a while and use a jumper wire to keep a connection between the negative battery cable and the negative battery post while you disconnect the battery. After you have the DVOM set up just remove the jumper wire. This will also hold your radio presets and the like.

 

[93 x]

I have tried everything I could think of, searching this forum forever and plugging in parts like an idiot! I will try to keep this as short and to the point as possible.

I have had a flickering/surging voltage gauge in my 91 ex. along with surging/dimming headlights for a while now. First the starter went, so thats new. Then I replaced the Alternator with a brand new not reman. one. Next I put a new battery in, and finally this week, brand new OEM battery cables. I thought the cables would do it since mine were all corroded and green and I have put new heads on twice in the past. New positive and ground!

Now its usually when I start the truck up after its cold, I get a flickering batt. gauge, along with surging dimming headlights. After I drive it around and it warms up after about 5 mins or less the gauge stops bouncing and theres no more dimming, all is well!?!? The needle is steady right between the R and M, right in the middle.

Please guys I am done, tired of trying...ready to go get a new truck. Any more ideas??? Thank you.

i kinda have the same problem i think its traced to the 12 volt positive on the alternator try to jumper the switch 12 volt strait to the battery that might work. the alternator needs a 12 volt positive to return the power.

 

[94explorerEB]

I have the very exacted same problem, low voltage at first then once driven it acts right

 

[Tbars4]

...If we get some feedback from the voltage test mentioned here, it may be of some help to others suffering from the same problem...

 

[Reejerey]

I'm sure it would help people with the same issue, kinda like a factory tsb.

 

[93 x]

yea i think im going to do a write up about it sunday. after the george strait concert here so ill do a write up with pics and what not and hopefully it will be a sticky i know exactly what the problem is i had the same problem with a 280z that had a small block in it also with my other car too but for now just give it a good punch of the gas (about 2500 rpms) and you should be fine maybe do it a few times

 

[sporttractuner]

Help flickering lights

About 2 weeks ago, i was sitting in my truck having lunch (idling). All of a sudden, trucks spudders and dies.... battery is dead. I left it for a few hours, battery recovered enough charge to start. battery dies out and truck stalls. so i replaced the alternator with a new champion OEM. all is good.
yesterday the weather got cold. and i started my truck in the morning. Lights/dash/dome everything flickering. once it ran for a bit everything was fine. so i figured i'd put a new battery in(850 amp instead of 750 amp). this morning also cold... same problem. I've also noticed the lidle is a little rough while cold. and a small squeek(could be a pully, but i checked the alternator is mounted firm, and connections seam fine). Input??

 

[manimal]

I suspect that an older fuel pump may have a heavy draw until it runs for a bit and warms up, but just a theory that fits in with the parasitic draw posts.

I recently had the same problem but new battery and cables fixed it for me.

BUT... before I replaced the cables you could hear the fuel pump warbling in sync with the flicker of the lights/voltmeter. Not sure if the pump was a cause or effect on this one.

 

[jungleryan00]

sounds like the voltage regulator on the alternator, same thing happened to mine and it worked fine after i replaced it.