Quick electrical noob question

[veggiemike]

If I've got 12V going out the positive cable, should I have 12V coming back to it on the negative cable?

With car on, engine off, if I unhook the negative cable and connect a digitial multimeter to the neg cable and neg battery post, I'm only reading about 9-10V... Normal? Doesn't seem right to me... so I thought I'd ask those who know.

 

[nitto389703]

what exactly are you hooking up? usually you just need to run a positive fuse cable to the battery and the get shortest possible cable and find a good ground source like chassis.
testing the battery with the car off should read 12V maybe your alternator is not charging the battery fully test the voltage with the car on, also try cleaning your battery terminals.
if im wrong please fell free to correct me just trying to help a member :/

 

[veggiemike]

Battery's fully charged, reads 12.5V with voltmeter accross the battery terminals. Just trying to figure out how to tell if my grounds are all good. I've been having intermittent electrical problems for a while, and now it's not starting.

 

[nitto389703]

so your car does not start. does it even crank or engine wont turn over, and what kind of intermittent problems are you having?

 

[ttocs]

the way you disconnected the battery and then inserted the meter inbetween the battery and the power wire is for measuring current. Current is abbreviated with an "I" and measured in amps so if you had it hooked up this way and measuring voltage you will get a strange number.

Set the meter to read DC voltage <20v. Do NOT disconnect the battery and now simple touch the red lead to the + side of the battery, the black to the neg and now see what voltage it reads.

 

[ttocs]

To test the grounds all you can really do is connect the red lead to the + side, and then touch the black lead to a part of the body that doesn't have paint, or at the factory ground. Should show close to the same voltage if you have good grounds. Now do the same thing but touch it to the block and see what it reads again.

But to be honest the only real way to check them is to trace and unhook them. Clean the areas under the connections as well as the ring terminals on the end of the wires and then reconnect them. Do this both for the batt-body ground right next to the battery and the body/block ground which on my 94 is on the lower passenger side of motor.

 

[veggiemike]

Car was running fine, starting fine. Then i had a few times where I could turn the key and nothing would happen, turn it again and it would start. Just happened once or twice, so I figured I didn't have the clutch depressed all the way or something. Then 2 weeks ago I had a couple instances where I would turn the key a dozen times before it would finally start. Holding the key in the start position for 30 seconds would eventually get the starter to engage. Then it eventually turned into a never starting problem.

By "not starting" above, I mean the following: LIghts good, radio good, battery looks fine, turn the key all the way, see all the lights on the dash light up they way they normally do when the starter is operating, but nothing. No starter noise, no clicking, nothing. Looks exactly like you forgot to push the clutch in.

I had a AAA guy start the car by connecting the starter directly to the battery while I had the key in Run (so fuel pump was primed, etc) and I drove home.

I proved to myself that the problem is not the clutch pedal sensor by unplugging it and connecting the leads with a wire (i.e., so the sensor is completely removed from the circuit). didn't help.

Now every once in a while, when I turn the key, it does try to start. Starter engages, engine fires up, but stutters badly for a few minutes then dies.

Also can't get my code scanner to work. Key on engine off test won't run when the test connector is plugged in... but every once in a while after trying to start the car WITHOUT the test connecter plugged into anything, i hear the key on engine off test start to run...

So, seems like i have something electrically totally out of wack... Figured I'd start by verifying that I have a good ground, since I'd heard that can cause intermittent electrical probs.

 

[veggiemike]

the way you disconnected the battery and then inserted the meter inbetween the battery and the power wire is for measuring current. Current is abbreviated with an "I" and measured in amps so if you had it hooked up this way and measuring voltage you will get a strange number.

Set the meter to read DC voltage <20v. Do NOT disconnect the battery and now simple touch the red lead to the + side of the battery, the black to the neg and now see what voltage it reads.

Well, I had it inbetween the neg terminal and the black wire... Dunno if that makes a diff.

Reading voltage across the terminals as you described gives me 12.5V or so.

 

[CC'S95GT]

If everything on the dash lights up except for the starter not turning. Sounds like the starter to me.
Have you pulled the starter out and have it tested?

 

[veggiemike]

To test the grounds all you can really do is connect the red lead to the + side, and then touch the black lead to a part of the body that doesn't have paint, or at the factory ground. Should show close to the same voltage if you have good grounds. Now do the same thing but touch it to the block and see what it reads again.

I just did this. Red lead to batery + term, black lead to grounds, block, and headers. All read 12.5V.

But to be honest the only real way to check them is to trace and unhook them. Clean the areas under the connections as well as the ring terminals on the end of the wires and then reconnect them. Do this both for the batt-body ground right next to the battery and the body/block ground which on my 94 is on the lower passenger side of motor.

Yeah, I disconnected the ground connector on the driver's side motor mount yesterday and cleaned it off with a wire brush... was pretty rusty though.

 

[veggiemike]

If everything on the dash lights up except for the starter not turning. Sounds like the starter to me.
Have you pulled the starter out and have it tested?

Well, it started the engine just fine when the AAA guy connected it directly to the battery. And it starts for me once in a while, too.

I just went outside and tried again. Started, but ran reeeeealy rough. After a minute or so, it actually started the Key On Engine Running test (the one where it spikes the RPMs to around 2k for 30 seconds or so). Ran just fine at 2K RPMs, then went back to sputtering and coughing until i shut it off. And this was with the test connector UNPLUGGED.

And after than, turning the key resulted in nothing but lights on the dash... sigh.