Low voltage after wire tuck,battery, and fuse box relocation

[freakingbori617]

So Ive been in the process of my relocations and finally finished up. But im having a problem with low voltage while cranking. Voltage at the started drops to 6-7v, while cranking. Here is a diagram I made to show how the wires are set up. The purple wire are the four thick wires from the fusebox that are paired directly to the battery post on a normal car.

 

[LeeSD1]

You'd want the 200amp fuse after the alternator before the fuse box. And I thought it was normal for volts to drop low during cranking? Since the starter takes up so much power. I dont know about 6-7v though, Are you sure your battery is Fully charged? what is the Volts at the battery with the car off?

 

[freakingbori617]

You'd want the 200amp fuse after the alternator before the fuse box. And I thought it was normal for volts to drop low during cranking? Since the starter takes up so much power. I dont know about 6-7v though, Are you sure your battery is Fully charged? what is the Volts at the battery with the car off?

I checked with another battery with same results. Also the battery read 12.5v. Even with a battery charger connected to jump start it didnt get enough juice to start up. Im going to do a load test in the moring.

 

[NHerron]

Relocation? You mean battery in the trunk? If so, the cables may not be big enough and with higher loads comes more resistance. Check the voltage at the battery POSTS while cranking. Then check the voltage between starter terminal to ground. Subtracting the difference will yield the overall voltage loss, but does not pinpoint whether it's the positive or the negative cable.

Grounding to the starter is the most likely cause if the battery is not relocated though.

 

[goldeninja20]

Relocation? You mean battery in the trunk? If so, the cables may not be big enough and with higher loads comes more resistance. Check the voltage at the battery POSTS while cranking. Then check the voltage between starter terminal to ground. Subtracting the difference will yield the overall voltage loss, but does not pinpoint whether it's the positive or the negative cable.

Grounding to the starter is the most likely cause if the battery is not relocated though.

We also tried taking another the battery and moving it up to the front of the car and running a zero gauge power wire to the starter. I grounded that battery. So there was a whole battery powering the starter and yet still it couldn't yield enough power to really turn the motor over well. I was thinking it had something to do with the ground on the starter also. We did have a ground on the bolt that holds the starter on. The only problem with the 420a is that there is no ground post to ground a wire.

By the way. I live near freakingbori617. We have been working together with the wire tuck and relocation. He is at work and unable to respond.

 

[nickk90]

Do voltage drop test on all your powers and grounds and it will lead you to the problem.

 

[goldeninja20]

Do voltage drop test on all your powers and grounds and it will lead you to the problem.

Another update. I tested the battery while cranking and starting while cranking again. On the battery while cranking I got 9.9v. On the starter while cranking i got 9.8 volts. This makes me believe that the wire is the correct gauge. The starter still struggles to turn over, if it even turns over at all. The starter is fine, I switched it with another 420a that is running. Is 9.8 volts not enough? What else could be my problem. The starter switch is supplying 5 volts exactly.

I also have no ground on the starter because i cant seem to figure out what needs to be grounded. Before the relocation there was no ground from what i can remember.

 

[luv2rallye]

You MUST have at least 9.6v minimum ON the starter positive post WHILE cranking. While cranking, check battery voltage and all voltage drops across each connection and cable to find problem. Include all connections to ground, other involved cables, posts, connectors. Problem is usually bad ground - even 0.05 ohms anywhere in starter power circuit (positive or negative) will drop too much voltage for starter to work properly. All starter power circuit connections must use a heavy bolt and large connector spade/terminal with all paint scraped off.

 

[goldeninja20]

You MUST have at least 9.6v minimum ON the starter positive post WHILE cranking. While cranking, check battery voltage and all voltage drops across each connection and cable to find problem. Include all connections to ground, other involved cables, posts, connectors. Problem is usually bad ground - even 0.05 ohms anywhere in starter power circuit (positive or negative) will drop too much voltage for starter to work properly. All starter power circuit connections must use a heavy bolt and large connector spade/terminal with all paint scraped off.

The starter is getting 9.8v while cranking. And the 420a is much different than the 420a starter. There is no specific terminal for grounding. So basically i think it is suppose to ground itself. The only ground that would be interrupting it is the battery ground, which is okay.

This has got to be the most aggrivating problem i have had. The starter is getting atleast 9 volts while cranking. It will just hardly turn over. The signal has 5 volts. Why wont it turn over right, I even tried another starter that is working and it is doing the same thing.

 

[NHerron]

How did you measure voltage drop at the starter? One probe should be on the starter aluminum case (ground) and other probe on copper positive post back of starter, while cranking. I would use alligator clips.

 

[goldeninja20]

That is how i measured it. It is getting 12.5 without cranking and 9.8 when cranking.

 

[Josh97eclipse]

How is the starter grounded?

 

[killab443]

I'd check your grounds. Esp if you resprayed the engine bay.

 

[goldeninja20]

How is the starter grounded?

I had it grounded on the top bolt that holds the starter in. It went to the factory ground spot on the strut tower, I have sanded to bare metal. After some more problem solving i have discovered that my signal is only sending 4.5 volts. Shouldnt it be sending a full 12 volts?

 

[born2tune]

I had it grounded on the top bolt that holds the starter in. It went to the factory ground spot on the strut tower, I have sanded to bare metal. After some more problem solving i have discovered that my signal is only sending 4.5 volts. Shouldnt it be sending a full 12 volts?

ofcourse.

look in to the manual and look for all OEM grounding points/posts. make sure you still have them grounding.

Maybe consider adding a ground wire from the engine to the body and the trans to the body.

 

[goldeninja20]

Do you really think grounds would affect the amount of volts my signal is supplying?

 

[NHerron]

If battery and starter voltage drop tests come out to be the same during cranking and above 9.6V (as luv2rallye mentioned), the cables and battery are confirmed good. You said you swapped starters out so it's a good chance the starter is good as well.

But you're saying you're only getting +5V on the signal (small 16ga wire hooked to starter)? That should have +12V there with key in crank position, but if the starter is at least cranking, the signal should not be a problem at that point. Maybe the actuator inside the solenoid (which connects the two high current posts together to supply current to starter) isn't making as best contact as it could, due to the lower voltage. I suppose it's possible but I've never dealt with it before. Try jumping +12V from the battery to the signal tab on the starter and see if there's a difference.

 

[goldeninja20]

ok another update. I took the starter and put it into another 420a. It starts right up, without a problem. So i put it back in the car. It is getting a good straight 12v power. The switch is still only getting only 5v. I tried to run a straight 12v to the switch, and nothing happens (not even a spark). THE ONLY WAY I CAN GET IT TO CRANK FAIRLY STRONG IS BY JUMPING THE STRAIGHT 12V ON THE STARTER AND THE SWITCH ON THE STARTER. This has to be one of the weirdest problems i have ever had. The ground on both of the 420as is in the exact same spot and both are sanded to bare metal. Everything is set up exactly the same on both cars, but this 420a wont crank at all even with a straight 12v source. Like i said the only way to crank it is to jump the 12v source and the switch. I KNOW THE STARTER IS NOT THE PROBLEM.

 

[freakingbori617]

FIXED. The ground from the starter wasnt a good ground, I sanded the chasis connection to metal. And charged the battery and was fine. The reason why placing 12v directly to the starter signal wasnt working, was because we were running that wire from goldeninja's battery which didnt supply current since the source was from a diff. circuit.

 

[Josh97eclipse]

weird, my starter isnt grounded and mine started perfect

 

[goldeninja20]

for future reference for people. As long as any part of your motor (transmission,block,head) is grounded to the any part of the chassis then your starter is technically ground. I guess you learn something new everyday.