superevil

1.will the car start if i remove the little harness on the back on the alternator that sends power ground to the ecu? (just wandering)
2. on the cpu and the fuse block.are there harnesses i can unplug and still run the car?(i am tracing a short that is draining voltage,if i can unplug systems and run the car i can narrow down where the short is) i know on my old tercel there was a harness that would cut power to all inside electric.just wandering.
3.is it wrong to want to push your car in front of a train because of electric problems?

Scott 89t2

why would you want to start the car to find shorts? I don't see how that would help. and might just cause damage.

all you need is an ammeter between one battery post and the wire for it. and start unpluging stuff till the current on the meter drops.

dubrc

reguarding question #3, I hope your talking bout your tercel

AcidShock

iTrader: (49)

In regards to question #3... if you are inclined to push it in front of a train, please notify me as I will come and pick it up. No charge to you!

Scott 89t2

edit: stupid forum errors

superevil

ok i really like the ammeter idea,do you mean ohm meter?or is there really an ammeter.so all i do is put the meter between one of the battery posts and the battery cable,and if theres a short in the system the meter will jump around?.should the ignition be turned to acc or on? or just turned off. if you could go a lilttle more in depth with the procedure that would be awesome

Scott 89t2

if the battery is draining with the car off. then current is flowing in / out of the battery that shouldn't be.

if you remove one of the battery wires. and connect an ammeter between them it will measure the current. (normal volt meter should work. you just set it to read amps (not ohms or volts)

under perfect conditions it will still have current flow. but very little. I think under 100mA. to run the clock etc.

with the metter connected. you can start pulling fuses inside the car one at a time. hopefully after pulling one the reading on the meter will drop. then you can narrow down which wires are shorting. if non inside do anything. go to the ones under the hood. and lastly unpluge the alt if no change.

the only concern is it it's draining really really fast. (like less then a few hours) the current could be more then the meter can handle and damage it.

if it takes longer it should be fine.

when you fist hook it up. you can open and close the door and you should see the reading change when the inside light turns on/ off to confirm the meter is working / reading.


and leave the keys out. leaving them on would just bring more current through the meter which will A, increase damaging it, and B make it harder to know when it's as low as it should be.

dubrc

good tips scott. most VOM's (Volt Ohm Milliameter) are fused to protect over current, my fluke is rated at 10 A, which if scott is right in his assumption that it's draining quickly, will probabily blow the fuse. Hopefully you do find the circuit that is shorting and then follow the FSM wiring diagram and use an ohmeter to check each component to ground untill you find what is shorted (little or no resistance from power/positive to ground). Bingo, bango...good luck

superevil

its draining very slow. and while driving the volt meter will go from 10-14,back and forth every few seconds,along with all the lights going bright and dim.brand new alt and battery.non of my warning lights come on when the key is turned to acc(i know some of them are suposed to),and i tried three sets of warning lights(junkyard)i replaced the ecu and am going to replace the cpu.after idling for about 5 miutes the idle will get shaky,and when the idle dips,the volt meter moves along with the idle dip,(goes up). when i first start the car and its idleing,the alt and batt will test 14.5 approximately,but if i move the car,or prety much do anything and then test the alt again,both it and the batt are about 11-12 at idle. on the highway,at a constant 2.5-3k rpm,the volts will go from 10-13,14 every few seconds,and its a sudden thing,not a slow thing,itll just drop all the sudden,all the while affecting the lights,heater,ect.and i know i go the belt tightened coorectly .i will do the ammeter test,but are there tests you can do that would solve electrical problems that are only problems when the car is started? i can still start it everyday,but its getting progressively worse.wich means the problem is worse when the key is "on" or started,or only when the key is "on" or started.

Scott 89t2

if you have driving problems it might be something else.

that test is more for if everytime you leave your car for 2 days the battery slowly dies on it's own and you can't start it.

superevil

cool,but do you know what i should check,or where you would look? or a way i could eliminate possibilities?

superevil

i got an idea,since my idiot lights never ever come on,and i know its not the lights that are broke.there has to be a problem with the ecu,or the line to the ecu from the alt,or the line from the ecu to the lights.could i run two wires from the back of the alternator(the plug),directly to the ecu,and bypass the existing wiring to the ecu from the altjust to test it? and are the wires white w/black,and black w/white at both the alt and ecu ends?

superevil

ok here goes,i took out all fuses that the car would run without inside.i started the car and let it idle for awhile.it was averaging 10-12 volts. then the idle would drop and the voltage would go up every few seconds,i was down by the fuse box when i noticed,that when this idle-volt thing happened,i heard a click from the cpu,every single time CLICK-then the idle would drop and the volts go up for a second, WHAT IS THIS?

Icemark

The click in the CPU means that the alt has failed to send a running signal... That means the alt is not working!

All your idiot lights should come on, on every click as well. If they do not, there is probably a problem with cold solder joints in either the clock/warning panel or the CPU.

Anything under 12.6 volts on the voltmeter means the alt is not even making enough juice to run the car and you are running only on the battery

superevil

what your saying makes perfect sense,it does,and i know you know what your talking about,prolly more than anyone else on this board.but why does it do this,and i can drive the car around for 50 miles,lights flickering all the way,and let the car sit overnight,and start up like the battery is brand new in freezing wether,i took the alt back to pep boys,and they said the alt is fine,but all my symptoms point to bad alt.when i first start the car.itll test @14.5,but after a few seconds it just drops and stays.would it be a bad idea to take it to a shop and say,"find the problem?"--and i mean taking the whole car not just the alt.....

Cwaters

My alternator was bad but it would only freak out once it got hot. When it was cool enough to take into the parts store, it tested out ok...put it back in the rotary inferno and BAM, the voltage regulator was wonky...

Cory

Icemark

Pretty common to have an alt get worse when it gets warm, when it is on its last legs.

The other thing you would look at would be the belts slipping when warm... but I doubt that is the case here

superevil

i friggin finally figured it out,my alt tested good at pep boys 3 times,they said there machine simulates a load being drawn too.,so finaly i got buy a alt off an 86 t2 at the junkyard for 15 bucks,and it works fine,even when everything is on. so i try to take my new (remanu) back to pep boys and they wont give me my money back because it tested good again!!! but while im sitting there trying to explain the story to the guy,the alt on the machine drops to 9.5 volts and holds,i was like "HAHA",and then he gave me my 100 bucks back,40 of wich im using to by an s-5 alt that is like a month old of a wrecked 91.....christ. i cant believe it tested good three times,what a piece of ****,ill never buy a remanufactured alt again

Icemark

Was it remanufactured, or was it rebuilt? Two different things!

And (I don't know how many times I have posted this) never trust a parts store test for an alt. They never check the alt correctly.