chasing a short renix

[RollTider]

89 4.0 auto. With everthing off im showing 9.10 volts at the battery after its been sitting. Showing 9-8 volts from the ground back to the ground post. Unhooked everthing but the hot wire from the starter relay and that droped my ground wire to ground post volts to .04. Hooked up the alt wire and that jumped the volts back up. Anyone have a diagram for the start relay? My hanyes manual doesnt look anything like mine.

Thank in advance

 

[Matthew Currie]

The first thing I think you have to do is to measure amps rather than volts. Remember that you will always have some drain, if only from the clock and radio memory, and that drain will always create a potential in the lines, so before you start chasing you need to know how much current is involved. If you get a current more than you think is reasonable, or if you are already getting battery run-down, the next step is to leave the ammeter in the line, and start pulling fuses, one by one. Expect a current draw of something around 30 milliamps normally, perhaps a little more if you have remote locking or alarm, but 50 is probably as much as you should accept.

A prime candidate is the interior light circuit, which is also the radio memory and clock, so pull that one first. If that drops your current down, you can then start trying to troubleshoot that one. Shorts in the rear hatch light are common, and you should make sure that visor and glove box lights aren't sneaking on when you're not looking.

 

[Ecomike]

Your data sounds odd to say the least, but it sounds like the alternator is bad, short inside, but it also sounds like the ground you were measuring is bad too, probably burned up inside the cable somewhere, melted, from the short. There are fuse links in the wires at the small starter relay near the battery!!!! 8MUD has been good about posting those little wiring drawings. PM him.

Battery should be 12.65 volts with power off. Disconnect the alternator again to remove the power-short, and check the ground wire again, but use the ohms scale this time.

MC's fuse check may be worthwhile too, to isolate the bad part, like the alternator.

VR is in the Alternator on Renix!!!

 

[RollTider]

Grounds are new. Pulled fuses on radio and inside lights and nothing changed. Don't have amp meter. I can jump the truck and it runs fine and I charge the battery . Im pulling my hair out

 

[Matthew Currie]

You have a voltmeter. Does it have no amp or milliamp settings? If not, these days a useable digital multimeter is so cheap there's no good excuse for not having one if you're doing this kind of work. Sears, big box stores, hardware stores, etc. have decent cheap ones, some for 10 bucks or less. For a little more you can get a pretty nice one that will do all you need and more. Most of these generic meters will have a 10 amp setting, which is more than enough for the testing involved here. You'll probably be using the 200 milliamp setting anyway. If you really want to track down a current leak, it's well worth it.

 

[Ecomike]

There is no way you can read 9V from a ground to the battery ground post if the ground is any good, new or not!!!!!

 

[Ecomike]

You also might want to take the battery in for testing. They can pass a meter test but fail a starter load test.

 

[wsar10]

^^^ yeah you deff. need draw tests to diagnose a draw issue....
Remeber; voltage does not really mean much (sometimes when dealing with higher capacitance circuits),

voltage - is just electricity's ability to "flow"
Current (amps or draw) - is the amount of electricity "being consumed".


If you think your starter relay is at fault just swap it with one close by than check the circuit again, IIRC.... your NSS relay is where your starter (solenoid) gets it's ground.

 

[wsar10]

There is no way you can read 9V from a ground to the battery ground post if the ground is any good, new or not!!!!!

sure ya can...you have hi voltage and low voltage.
His tester probably is just not displaying the diff.

 

[Ecomike]

Current (amps or draw) - is the amount of electricity "being consumed".

That is watts not amps.

100 amps at 480 volts is lot more "being consumed" than 100 amps at 1 volt.

-----------------

Originally Posted by Ecomike
There is no way you can read 9V from a ground to the battery ground post if the ground is any good, new or not!!!!!


"sure ya can...you have hi voltage and low voltage.
His tester probably is just not displaying the diff."

BS! And that depends on the meter he has, not all are alike. IF he has a good meter, and is using it properly, THEN "A standing voltage of 9 volts on a ground connection means that ground connection is no longer grounded to the negative battery post, especially when the battery is reading 9 volts post to post".

If you are suggesting that he does not know how properly use his meter, then say that.

My suspicion is there WAS a short, and it burned a ground wire up while it drained the battery. Only other option is a bad meter, or he needs to learn how to use the meter, or all three, or both, LOL, IMHO.

 

[wsar10]

That is watts not amps.

100 amps at 480 volts is lot more "being consumed" than 100 amps at 1 volt.

-----------------

Originally Posted by Ecomike
There is no way you can read 9V from a ground to the battery ground post if the ground is any good, new or not!!!!!


"sure ya can...you have hi voltage and low voltage.
His tester probably is just not displaying the diff."



BS! And that depends on the meter he has, not all are alike. IF he has a good meter, and is using it properly, THEN "A standing voltage of 9 volts on a ground connection means that ground connection is no longer grounded to the negative battery post, especially when the battery is reading 9 volts post to post".

If you are suggesting that he does not know how properly use his meter, then say that.

My suspicion is there WAS a short, and it burned a ground wire up while it drained the battery. Only other option is a bad meter, or he needs to learn how to use the meter, or all three, or both, LOL, IMHO.

you are correct on my mistype.........I type too fast on breaks @ work
amperage is the rate THAT electricity flows....

as far as BS on hi or lo voltage ????? thats not correct.
You called that statement BS but then talked around it writing it off as a meter difference,
Or maybe I misunderstood.....

 

[RollTider]

There is no way you can read 9V from a ground to the battery ground post if the ground is any good, new or not!!!!!

Plz tell me what I'm doing wrong then?

 

[cruiser54]

It would be nice if we could see which scale the meter is set on.

 

[Ecomike]

Plz tell me what I'm doing wrong then?

LOL, for one thing, like I said before, the ground clamp at the end of that cable is not attached to the negative battery post, therefore it is "Not grounded", , LOL!!

All it would take is a very tiny power load, like an ECU/PCM memory power load, or a radio or dash clock memory power load, or car alarm, to show that reading, which means nothing, because they use a very tiny, tiny amount of power, are known to be there, and prove nothing.

Now if you disconnect the positive battery clamp, reconnect the negative battery clamp, then test using the low range ohms scale from the negative battery post to the engine and firewall and sensor grounds, you want to see less 1 ohm readings, otherwise there is bad ground.

If you do not have a current meter you can still do the above, and pull fuses, or buss wire connectionss to the starter relay one at a time, and reconnect the positive clamp just barely to see if there is a spark. A spark means a large load, no spark means little or no load.

 

[Matthew Currie]

That meter has an ammeter. It's just what you need. Use the ammeter. Put the positive lead into the 10 amp jack and read the current, not the voltage, between the battery ground and the ground cable, or between the battery positive and the positive cable. It doesn't matter which you use with a digital ammeter (if you use positive, reconnect the negative cable, if you use negative, connect the positive cable). You should see a very small current if all is working correctly. If it reads a current below .2 amps, you can replace the lead back to the usual jack and use the 200 milliamp scale for more precision. If the current drain is greater than about 50 milliamps, you need to trace the problem. If it is not, you need a new battery.

You'll never track down a parasitic drain with a voltmeter.

 

[RollTider]

That meter has an ammeter. It's just what you need. Use the ammeter. Put the positive lead into the 10 amp jack and read the current, not the voltage, between the battery ground and the ground cable, or between the battery positive and the positive cable. It doesn't matter which you use with a digital ammeter (if you use positive, reconnect the negative cable, if you use negative, connect the positive cable). You should see a very small current if all is working correctly. If it reads a current below .2 amps, you can replace the lead back to the usual jack and use the 200 milliamp scale for more precision. If the current drain is greater than about 50 milliamps, you need to trace the problem. If it is not, you need a new battery.

You'll never track down a parasitic drain with a voltmeter.

Thanks, that's what I need to hear. Not "Your doing it wrong"

 

[Ecomike]

That meter has an ammeter. It's just what you need. Use the ammeter. Put the positive lead into the 10 amp jack and read the current, not the voltage, between the battery ground and the ground cable, or between the battery positive and the positive cable. It doesn't matter which you use with a digital ammeter (if you use positive, reconnect the negative cable, if you use negative, connect the positive cable). You should see a very small current if all is working correctly. If it reads a current below .2 amps, you can replace the lead back to the usual jack and use the 200 milliamp scale for more precision. If the current drain is greater than about 50 milliamps, you need to trace the problem. If it is not, you need a new battery.

You'll never track down a parasitic drain with a voltmeter.

On the other hand, one can look for fire, smoke, or a hot spot in the wiring harness, to track down damn parasite, LOL!!!!

 

[RollTider]

No problems like that. Jeep runs fine after a jump. Battery tested good not long ago when I was having other wiring problems.

 

[Ecomike]

Batteries can test good one second, then short out a plate and go bad a second later. 10.9 volts post to post sounds like a fried battery to me!!!!

 

[RollTider]

That's after sitting over night but ill check it again