RX-7Havik

Here's the deal guys....
buddy of mine has got an 89n/a, automatic. Has been having trouble holding a charge. Thought it was a bad alt or weak batt, so he changed both. Still having the same exact problem as before......starts fine, drives a little and sure enough, lights start dimming and car starts losing power until.....DEAD! Any idea on what it could be? Bad ground is what I was thinking. Are there any checks he can run?

lgjp2631

bad ground is a good start but your starter is a big part of your charging system too.odd but true.if you have a rgound prob try putting your test light on the pos batt terminal.pull the wire off and put one part batt and the othe to the matching wire if it lights it is def ground prob.then do the same with neg side.if the test light is on. start pulling fuses until it goes out.then you will know where to look for the ground. hopefully i didnt confuse you if so pm me. good luck, jason

Molotovman

iTrader: (49)

does youre friend have the sleepy/lazy eye mod on the car? I've read it drains the battery due to pulling the fuse for the lights.

Icemark

if the engine is running and the car goes dead from no voltage, then it is not a battery problem, but rather his alternator is not working or connected

KingCobraV9

iTrader: (2)

or it could be bad terminals or terminal connectors. my gxl did that then i changed the terminal connections and the battery. works fine now.

RX-7Havik

Thanks, I will pass on the advice and let you know what the results were! Icemark....he put a new alt on....doesn't that rule it out? I know you initially start off of bat, but then the alt takes over. I guess if alt is not doing it's job you will run off of batt instead till it drains eventually. Anyway, thanks a bunch fellas.

Icemark

This is a Turbo????

On the Non-Turbos there is a voltmeter... it should always be above 13.5 volts if the engine is running.

RX-7Havik

N/A.....I'll see what it reads. I have a N/A as well and that is what I read.

deltr0n`

If he has a rebuilt alt he will have at least 14v, so that cant be it... it could be a bad battery that wont hold a charge, it happend to me with an OPTIMA!...tested the battery and indeed it was BAD. Another crazy but true thing are the headlight motors like Molotovman mentioned, sometimes they get jammed and they dont open or close all the way, and the motor is still on trying to open or close it the whole time while its draining your batt. That was the case with my newly aquired TII.

Icemark

A bad battery won't matter while the car is running... When the car is running the batery is acting like a giant capcitor, and should not have any influenece on the alternator at all (other than to give a reference voltage so the alt can tell if it should make more voltage).

And I have seen a ton of crappy auto zone rebuild alts that last about a week

deltr0n`

I know that, but when the car sits overnight it dies down cause theres no alternator charging it. And who gets rebuilt alts from autozone? not me I goto Rotex, they give you a dyno slip of the alternator and they have like at least a 2 or 3 year warranty.

flubyux2

Hey, im having this problem on my 90 GTUs... ive changed both the alternator AND the battery.

the battery one charge at all. its dead. ive gone so far as to eliminate ALL the factory wiring and run a jumper cable from the alternator post to the battery + post, and another jumper cable from engine ground to the battery - post. ive been driving it like that day in, day out. just today, i took the cables off the alt/engine and tapped them together, no spark, no nothing. battery is deader than a SOB.

i have to jump the car every time. cuz when the key turns to ON w/o the Jumper, theres nothing...obviously. no clicks or anything. but when the jumper batt. is hooked up, the car comes to life. and im jumping the car w/ the jumper cables hooked straight to the in-car Pos and Neg battery terminals... not Pos terminal and Engine ground.

i checkd my Main 100A fuse, it checks out ok. i dont undesrtand what it is. there is something keeping the battery from getting current from the alternator, DESPITE the fact i have a jumper cable running directly from the alternator itself.

Icemark

what is the current draw on the car? Should be less than 70mA (.07 amps on most digital meters).

and are you sure you have the 2 pin plug on the alt connected and wired correctly?

Icemark

alternators only charge when the engine is running. A fully charged battery, sitting and dieing overnight is a current draw or bad battery issue.

WAYNE88N/A

Pull all of the hot battery bus fuses out of the cabin fuse box at night (top row of fuses), for troubleshooting...This should eliminate any current draw problems from the circuits that are normally powered all the time (every other fuse in the cabin box is powered through the ignition switch). If that seems to fix the problem, leave in one fuse at a time when you pull 'em for the night. If, after a fuse is reinserted, the car is dead again the next morning, you've found your problem circuit.

Have you guys added any new items to the electrical systems of the car recently? New deck, fog lights, new "grounds", etc...

14.4 volts should be the lowest charging voltage outputed by the alt per the FSM...

Only one dead cell in your battery could play havoc with normal charging operations...

Icemark

Pulling fuses for current draw testing is like using a test light for current draw testing. Highly inaccurate and will probably not help one bit.

WAYNE88N/A

Using a test light (or meter) for amp draw is all fine & well, but doesn't do a damn thing to tell you which circuit is drawing the current. Isolating an entire circuit (accomplished by pulling fuses), or portions of a circuit (by removal of plugs or components) is how you locate a short, which is nothing more than an abnormal current draw...

flubyux2

well, the car is BONE stock... just the way id like to keep my 1 of 100 GTUs. the only thing aftermarket is the wheels/tires. so the factory wiring is 100% intact.

the car actually produce 14ish volts while driving or anything above idle.

Mark, are you saying to pull the Pos battery cable off the terminal and test to see if there is any current draw while the car is off? ill look into that... but thats under the assumption that i have a hidden current draw which is draining the battery while its not running. this isnt the case. i could be driving the car for hours. if i shut the car off and turn the key back on... nothing. i mean, its long enough to charge the battery up on a normal car yet does nothing.

there was one time, i was cruising down the freeway. just to test my theory of whether or not its an intermittent problem, id kill the motor while coasting w/ the clutch in... and cycle the key on and off till the guages came to life and then try to start it. once out of the 10 or so times i attempted this it started by itself. the rest of the times, the gauges laid dead and i had to let the clutch out to restart the car while i was coasting down the freeway. so, i dont know... sounds as if something somewhere is loose. ive had a similar problem on my Trans am where the starter solenoid Pos. post was loose and would make intermittent contact. i had to wiggle the battery cable around on the starter to get continuity and then start the car. if that was the case on this car, i wouldnt be able to jump start the car at all. but i can jump start the car 10 times out of 10 w/o a hitch... only thing is, its slow cranking, even if i had been charging the spare battery all night long and it was no longer drawing current from the charger.

WAYNE88N/A

Hmmm, do you still have the factory alarm & starter cut relay on the car?

flubyux2

yea, but i havent seen it work since ive owned the car (almost a year). if its anything like setting the S4 system, then no, i dont think it works.

WAYNE88N/A

If it's not the starter, what else could it be besides the ignition switch? Maybe the clutch interlock switch?

TurboSmoke

i had a problem with this happeneing to my car. it was the ground wire on the tranny not connected correctly. ask him if he has had any tranny work lately

Icemark

Yes to test current draw... you will need to remove the positive battery lead an insert a digital multi meter set for amperage and see what the current draw is.

Again you would want to avoid trying this with a test light, as it will only show if the test light works, rather tahn what the draw is.

For example a DMM will show you say 40 or 50 mA you would know there is no major draw on the car (really anything less than 70 mA is okay). Now how bright is 50mA on a test light???

anyway, say on your meter you have a 120mA draw... right there that tells you that either a relay is stuck on or a door/hatch switch... again though with the useless test light, how much brighter is 120mA than 70ma... can you tell the difference between a 5 watt and 7 watt light bulb... 99% of the world can not and that is a whole 500mA difference.

So, now if you have the DMM in there, then you can start pulling fuses (one at a time) and see what circuit the draw is on and go from there. But just pulling a couple of fuses and hoping that the battery still works in the morning... well is a bit of a waste of time... I don't know... maybe you have that much time each day/night to test. I know I would want to figure out my draw ASAP.

RX-7Havik

Icemark, so what you are saying is to pull the pos batt terminal off and stick a dmm on it and see what the draw is, while pulling fuses one at a time? which fuses in particular? Top row? All I know is, the guy with this problem has installed a new alt and new batt. Something is definitely drawing current from his batt. But this is what I don't understand....if something is drawing amps from batt, then why is it when he does have a full charge, say from a jump...the car slowly loses power until lights start dimming. Doesn't the alt take over from there? Second alt he's put on btw. So does the problem lie with a bad draw on batt or alt not putting out?

RX-7Havik

Gotta luv these cars, but damn...they are tricky. What would we do without this bad *** site huh!