electrical issues

[Hitmachine101]

ok this problem has been perplexing me for about a year now
When the car is stone cold, she starts fine and there are no lights on in my dash, everything is fine when i start her in the morning basically

if theres any warmth in the engine at all, when i start the car the battery light and the brake light are half light and to get them to go away i have to rev the car to 4200 rpms and then they go away and i have no issues from that point on, i can actually drive it with the lights on and there are no issues either but i figure all of this has to do with my altenator and the charging system

if the car is at idol, and i take the positive terminal off, the car dies, yet the battery is always fully charged and every time this car starts and runs fine,

the altenator is a autozone part and is about a year old, my last one puked on me and i replaced it with this one and the car continued to have this problem

another symptom of this entire issue is that when im driving and am coosting up to a stop light or sign, i put the car in neutral and she almost dies but then bounces back up to the regular 800 rmps at idol.

so my guess is that the altenator is charging the car when its anywhere above idol but not when it is at idol,, again the battery has never died on me nor has the car stoped charging it during this years time period

reason i ask is because my sister took the car for a 2 day period and somehow craped up the positive termal and everything went hay wire and the car died in a busy intersection and AAA was called because i wasnt near my phone,

I clean up the termal, the car starts right up and everything hunky dory again

I hate electrical issues, anyone with any ideas here? maybe an ecu issue? im sure you ll tell me to get a new altenator but it works sooo.... idk

thanks guys

 

[derektcasey]

Not a good idea to pull the battery cable while it is running. That is a good way to smoke an ECU. I would have the alternator checked again. Also, make sure you get the highest AMP alternator (75 amp). They always try to stick the manuals with 65 amp alternators.

As a side note, any aftermarket electronics (stereo, guages, upgraded fuel pump, etc...)? These can also put an extra drain on the alternator. I know mine never had issues until the headlights and wipers came on, then I had a charging issue.

 

[Hitmachine101]

Not a good idea to pull the battery cable while it is running. That is a good way to smoke an ECU. I would have the alternator checked again. Also, make sure you get the highest AMP alternator (75 amp). They always try to stick the manuals with 65 amp alternators.

As a side note, any aftermarket electronics (stereo, guages, upgraded fuel pump, etc...)? These can also put an extra drain on the alternator. I know mine never had issues until the headlights and wipers came on, then I had a charging issue.

never knew i could ruin an ecu by doing that so ill stop , would a 65 amp altenator really not charge the car at idol, im sure i have that one because i found the cheapest one i could at the time because i was broke,
the cars stock, no aftermarket stuff, stero fuel pump are all stock

if i had the 75amp this stuff would stop? possibly? why would an auto need a 75 vs a 65 like the manuals need?
thanks

 

[derektcasey]

I'm not sure why the Auto gets the 75 amp, but when I purchase, I go for the bigger one (just tell them you have an Auto). It always fixed my issues. BUt, these cars go through alot of alternators. I am going to do the Saturn Alternator siwtch. They are way more powerful, more reliable, and cheaper!!!

If your battery is a little weak, the alternator will have to work harder to keep up the charge. Eventually, you will get a squeeling belt/alternator and dead alternator.

 

[coryd21]

I have ran into this issue before. It's irritating to say the least. You are having a resistance issue in your charging system wiring. When the wiring is cold it will be fine but when it heats up the resistance will increase to the point that your charging light and battery light will come on.

I suggest get a wiring diagram for the charging system and do voltage drop tests when the car is cold and after it has warmed up. If you get any higher than a .5 volt drop then you can either A. just replace that whole wire. B. Hunt the exact spot causing the high resistance down and repair it, or C. You could even install an over lay wire for the damaged one.

We were having the same exact issue and this was our problem. Hope it helps you out.

 

[andrewschel]

you can test your alt with a multimeter while the car is running. you want to see 14v. if its a cold/hot problem then i think coryd21 nailed it. electrical problems are a pita. goodluck

 

[Hitmachine101]

I have ran into this issue before. It's irritating to say the least. You are having a resistance issue in your charging system wiring. When the wiring is cold it will be fine but when it heats up the resistance will increase to the point that your charging light and battery light will come on.

I suggest get a wiring diagram for the charging system and do voltage drop tests when the car is cold and after it has warmed up. If you get any higher than a .5 volt drop then you can either A. just replace that whole wire. B. Hunt the exact spot causing the high resistance down and repair it, or C. You could even install an over lay wire for the damaged one.

We were having the same exact issue and this was our problem. Hope it helps you out.

Glad someone had similar issues, great info, so the wire im looking for is the wire that runs from the altenator to the positive termal i imagin?

sounds like im getting my multimeter out and doing some diagnoising

appreciate the responce

 

[coryd21]

Actually I believe it will be the small wire from the battery to the alternator that tells the regulator in the alternator what the charge of the battery is. I think it will the S terminal but I might be wrong. Just break out a wiring diagram and you will see it.