I'm assuming the engine shuts off for a split second.

It usually happens on my track out where I push the car really hard to get the best exit speed. While pushing it, the Rpm and Speedo drop then comes right back where it should have been.

Yesterday my battery light would come on very dim at a stop. It would go away if I reved up a little. I'm guessing my alternator is shot. Could the alternator cause the first problem?


Modified by blaze_125 at 6:21 AM 6/21/2007

 

Go start your car, and at idle, remove the negative battery terminal. If your car dies, it's probably the alternator.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Eran &raquo;</TD></TR><TR><TD CLASS="quote">Go start your car, and at idle, remove the negative battery terminal. If your car dies, it's probably the alternator.</TD></TR></TABLE>

Will do.
I'm still a few hours away from being to do that. Anybody else have suggestions to throw in before I get out there?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Eran &raquo;</TD></TR><TR><TD CLASS="quote">Go start your car, and at idle, remove the negative battery terminal. If your car dies, it's probably the alternator.</TD></TR></TABLE>

Can you explain to me how that works? The alternator relays power to the battery before it goes to the coil anyways. So wouldn't the car cut out immediately even if the alternator was 100%?

There's no direct lines from the alternator to the coil - it's all relayed through the battery. You're breaking the connection, charged or not charged it'll stall out.

?

It won't stay running if you pull the negative terminal off - there's no place it holds the charge...

I don't know, I'm just ignorant to this method - please, explain.

@ OP:
It's probably 1 of 3 things, battery, alternator, or a loose ground.

The battery can probably be gauged much like a butt dyno in terms of "feeling" - how does it start? If it starts strong, like on the first turnover, then it's probably not the battery (although still possible).

If your alternator DIES you have whatever juice is in the battery - then the car dies, straight up, won't start, etc. etc.

If you are having alternator problems (as it's going out), it looks like the movie close encounters of the third kind - lights start dimming, with the car idle, like brighten then dim, in a cycle. It's especially noticeable on your cluster - it'll dim down, then pump up, same with ur headlights.

It's like if you don't give it enough gas when ur letting the clutch out and ur RPM drop to 300 and it shakes a little - if you notice it at night, the lights dim due to the lack of power because the alternator isn't being turned fast enough - same concept here except the alternator is going out.

If the lights are steady and on strong, I'd say the alternator's probably fine, though even so, you can pull it out and take it to autozone and it's like a 90% accurate test whether it's good or not, I'd definitely do that.

For the time being I'd swap batteries, this battery might have trouble holding a charge causing your drop out at high RPM when it has to fire a lot, if it's still doing it with a KNOWN GOOD battery, what I would do is pull the alternator, bring it to autozone, and have the free test done, see what they say the condition is. It's not 100%, but it's pretty damn close.

If it's still doing it with the new battery and the alternator checks okay, than it's most likely a grounding issue someplace, but I doubt it, probably the battery of alternator.

 

Thats a really old trick that works, the battery and alternator connects to the car's electrical system with no relays, just a fuse

 

The battery is a possibility, but I doubt it. It's not even 6 months old :s

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blaze_125 &raquo;</TD></TR><TR><TD CLASS="quote">The battery is a possibility, but I doubt it. It's not even 6 months old :s</TD></TR></TABLE>

I bought a battery for my benz ('90 300E) from interstate brand new in the wrapping (that's why mercedes uses OEM). About 3 days later it died - battery.

Some batteries are just defective. Never rule it out just because it's new.

EDIT:
AT OP:
You said you assume it's shutting off. Does the car JERK hard when this happens? If it doesn't your car isn't shutting off, if you're on it full throttle and the car dies for a half second, it'll jerk, straight up. Is the car jerking, or just the cluster needles are going down like it turned off.

 

The car will still run when you remove the battery cable, this is bad for the altenator however because once the battery is remove. The alternator will be charging at it maximum rate because there is no longer force pushing back at the alternator.

If your alternator was bad, then the car would run on your battery and once the battery run out, the car will die simply put.

 

The car doesn't really jerk, the radio doesn't shut off but it does feel like something is happening. It's really hard to explain. I'll try to get a better feel of it if it happens again on my way home from work. But it happens so quickly that's it hard to notice it until already over. It might just be my mind telling me the car shuts off too. I know every so often the tach will stop working for a few miles and come back on on it's own (That is most defenetly a bad connection).

Other than a bad alternator and/or bad ground, what else could explain the fact that the battery light comes on very dimed at idle and goes away when the rpm goes up?

 

The car doesn't really jerk, the radio doesn't shut off but it does feel like something is happening. It's really hard to explain. I'll try to get a better feel of it if it happens again on my way home from work. But it happens so quickly that's it hard to notice it until already over.

Other than a bad alternator and/or bad ground, what else could explain the fact that the battery light comes on very dimed at idle and goes away when the rpm goes up?

 

Did a small test when I got home and it points toward a bad alternator. I think.

Engine off - Battery voltage around 12
Engine running at 2k rpm - Battery voltage around 13.1-13.4

 

Your alternator is charging

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StolenTeg &raquo;</TD></TR><TR><TD CLASS="quote">Your alternator is charging</TD></TR></TABLE>
Shouldn't it read around 14-14.5 when the motor is running 2k rpm?

 

your charging voltage is fine, sounds like cam/crank sensor which would be in your dist.
any codes? rpms come from the dist. speedo comes from vss. check your grounds (clean them)

 

Ok, so the engine does not shut off and come back to life. I duplicated the problem yesterday and that problem seems to be some bad connections to my speedo and tach.

I'm still getting a dimed battery light though.
I'm getting the light when I apply a big load at idle (ie. lights ON, fog lights ON, Heater at full blast)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Eran &raquo;</TD></TR><TR><TD CLASS="quote">Go start your car, and at idle, remove the negative battery terminal. If your car dies, it's probably the alternator.</TD></TR></TABLE>

Tried that too. The car didn't die.
Does that mean I should rule out the alternator?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blaze_125 &raquo;</TD></TR><TR><TD CLASS="quote">

Tried that too. The car didn't die.
Does that mean I should rule out the alternator?</TD></TR></TABLE>

Yes, the voltage test means it's charging, and if you pulled the negative terminal and it still ran, it's fine. Rule out the alternator for now.

If you're not having trouble starting it's probably not the battery either. Usually the only problem w/ batteries is they can't HOLD a charge. So if it's starting fine it's probably not the battery.

If it has a removable top pop open the top (be careful, it's battery acid in there) and top it off with some distilled water. If not, don't worry about it.

If the radio doesn't shut off (it will at least stutter when it reboots if power it cut to the system) the power is fine. I'm guessing cluster problem or cluster harness problem - though which, I'm not sure.

 

check the ground on the alternator and make sure the battery is connected tight.

 

The car starts up fine.
I tested the battery like 1 hours after a 30 minute drive and the battery showed 12.8 volts with the engine off. As stated before my charging system seems fine.

Battery terminals are on tight. The positive side was really loose at the beginning of the week but my problem stayed even after I tighten it.

Would there be a special order to do things to troubleshoot the cluster? Or should I just go ahead and start taking the dash appart looking for a bad connection?

 

your charging sys. voltage @ idle is 13.1-13.4 with the system loaded? that is low

sounds like the brushes are going out, you need to have the alternator load tested.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Eran &raquo;</TD></TR><TR><TD CLASS="quote">Go start your car, and at idle, remove the negative battery terminal. If your car dies, it's probably the alternator.</TD></TR></TABLE>
this would be alright back in the day, but not anymore. i don't know when it started (pre 91), the alternator is controlled by the ecu. removing the neg. battery cable causes the ecm alt. duty cycle to go full bore and can possibly burn up the ecu charging control circuit.

 

sounds like a grounding problem to me. might wanna check the grounds and see if theyre corroded

 

one question you say you notice then when only applying a large load on the motor at idle. Well most hondas are are not charging the system at idle. Another thing could be a bad diode ripple in the alt we have had several car that test fine and when they are drive for a bit show signs of low battery or charging fault. Also check cables for hard spots some cables will have corrosion build up inside wire casing hard to spot but just feel the wires you'll know if there is a bad spot. this can sometimes cause low voltage and resistance problems. Could have a led problem too load electrical detector. Just some stuff I've run into with my hondas.

 

At first I thought the car was shutting off and coming back on because the cluster would go go off and on. I have ruled out engine turning off. I duplicated that problem and it seems only the speedo acts up.

But yeah, the battery light comes on only when a big electrical load is applied at idle, and the light goes away when the rpm goes up.

I guess that would mean the alternator is still somewhat good in the sense that it can still provide enough electricity when driving, but shows signs of wear since it can not hold a proper current at idle.

That tells me the alternator might completely go at anytime.

 

It could be alot more than every one here is telling you though. I've had things come into the dealer that I chase for a long time for problems like this. A good test is to have the car running and start shaking wires, harnesses, tap on relays..etc.