negative cable

HeWhoKillz · #1 12-24-2009, 05:38 PM

I feel stupid for even asking this question. Back to the sentra engine. Where does the negative battery cable go other than the battery? Its got a metal loop on the other end. Its just sad to say that after nearly everything else is connected and I can't figure out where the other end connects to. I thought the starter cause it also has a negative connector but I'm not sure and I knoow its not the alternator.

vgames33 · #2 12-24-2009, 05:40 PM

It bolts to the transmission bellhousing. It will use one of the starter bolts.

HeWhoKillz · #3 12-24-2009, 05:49 PM

Quote:

Originally Posted by vgames33

It bolts to the transmission bellhousing. It will use one of the starter bolts.

Is it used just for ground? So it really wouldn't matter where it was grounded to as long as its something metal right?

shorod · #4 12-24-2009, 08:01 PM

It is "just for ground" but the ground is critical. The ground connection completes the circuit for every electrical thing running in you car. If you use a ground that is not clean, you will have electrical issues and probably noise which can screw up the PCM, sensors, and the radio. If the ground is not capable of sinking enough current, your starter motor will not be able to get full current, nor will your alternator be able to supply full current to the system.

Hmmm, where would the two circuits be that require/provide the most current? The starter and the alternator, and both are mounted to the engine block. Therefore your ground cable should also be connected to the engine block. It is also critical that you make sure the ground straps/cables between the engine and the unibody of your car are properly connected, clean and tight.

-Rod

RahX · #5 12-25-2009, 04:33 AM

Like shorod said, ground it to the engine/trans. That is the shortest route for the circuit. And make sure there are groundstraps going from the engine/trans to the body to keep any stray grounds connected to the battery. Electricity will complete a circuit any way it can and it usually finds strange ways around your car if not grounded properly.

HeWhoKillz · #6 12-26-2009, 10:07 AM

Quote:

Originally Posted by RahX

Like shorod said, ground it to the engine/trans. That is the shortest route for the circuit. And make sure there are groundstraps going from the engine/trans to the body to keep any stray grounds connected to the battery. Electricity will complete a circuit any way it can and it usually finds strange ways around your car if not grounded properly.

If its not grounded, will this keep the car from starting?

shorod · #7 12-26-2009, 11:06 AM

If what's not grounded? If the ground cable from the battery is not grounded, yes, it will prevent the car from starting as well as any electrical circuits on the car.

If the cable is grounded to the engine/transmission but the engine is not connected to the chassis of the car via the ground straps, it may not necessarily keep the car from starting, but you will likely experience a lot of strange electrical gremlins, and it may prevent the engine from staying running. Many of the engine and transmission mounts are isolated with rubber, so you won't get a good electrical connection through them. All grounding in the rest of the car will be through sensors and wires that are rarely oversized to support much more current than the circuit is designed for. So you will have circuits that are started for current and therefore may not function properly.

If you ground the negative cable to the chassis/unibody and not the engine, you may burn up other wires when you try to start the engine as they become fuses for the 100 amps or so the starter attempts to draw through the smaller wires.

Your best bet is to get a ground cable the proper length to allow you to properly ground it to the engine block/transmission, then make sure the proper ground straps are connected between the engine and the chassis and reduce the number of problems that you have to troubleshoot later on.

-Rod

HeWhoKillz · #8 12-26-2009, 12:12 PM

Well, I grounded it to one of the bolts on the transmission/engine. I have another question. With the starter, there are two bolt ends sticking out. One is attached by a wire to the starter itself i believe. Which one is negative and which is positive? Or should i get pictures of this? I know the postive cable should attach to the starter but now I'm not sure which one.

shorod · #9 12-26-2009, 02:58 PM

If one of the lugs on the solenoid has a wire or metal bar going from the lug to the starter motor, that would NOT be the one to connect the positive cable to. The solenoid switches the electrical current to the starter motor, so one terminal is the input to the "switch" and the other is the output from the switch to the starter motor.

-Rod

HeWhoKillz · #10 12-26-2009, 10:09 PM

So the one without the wire going from the lug to the starter motor is the one that goes to the battery. Ill have to recheck my wiring on my sentra. I haven't connected the starter cable yet.

RahX · #11 12-27-2009, 03:33 AM

If you get it wrong, the starter will operate as if you had turned the key. Usually with the solenoid sitting on top of the starter motor, the TOP post is the one the battery cable connects to. The starter housing is the ground so the fact that it is bolted to the engine/transmission is all that it needs.

RidingOnRailz · #12 12-28-2009, 08:39 PM

Hmm. I wonder if this could explain the horrendous noises on my AM radio in my 2008 optima!

The noise persists whether key is in Accessory or Run, engine on or off.

shorod · #13 12-28-2009, 10:05 PM

That would be easy to check with a simple jumper wire connected between the engine block or ground cable and a clean ground on the unibody. Since you have the noise on AM and not on FM though I doubt the ground is the issue. You might have an antenna issue. The AM antenna may be mounted internal to the radio.

A 2008 Kia should have a warranty still in effect for the radio, right? You may as well let the dealer fight it.

-Rod

RidingOnRailz · #14 12-29-2009, 07:24 PM

Quote:

Originally Posted by shorod

A 2008 Kia should have a warranty still in effect for the radio, right? You may as well let the dealer fight it.

-Rod

BTDT. All the sets on the lot exhibit the same noise(a hair dryer on low) on the same portions of the AM band.

And as you suggested, FM is flawless for 50+ miles.

shorod · #15 12-29-2009, 10:56 PM

After driving 50+ miles did you try the AM radio again to see if maybe the noise was due to environmental conditions at the dealership? Amplitude Modulation is much more prone to environmental disturbances than Frequency Modulation.

-Rod

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