Electrical How many amps could an amp draw draw....

mikeynonos · Oct 17, 2021

Okay electrical gurus...I have a problem I could use a little assistance with. I purchased another 5.0, but the seller did not disclose the car had a drain on the battery. I have been checking the amps like has been discussed on here in numerous other threads, but removing fuses did not lower the draw. I have isolated the problem down to 3 wires of the at the starter solenoid.

The yellow 10-gauage wire that splits into the 4 smaller wires shows infinite draw on a 10a DMM.
The blue wire shows the same draw as well (1. )
The 4-gauge wire going to the solenoid shows a draw as well, of roughly .14.

With the rest of the wires connected to the solenoid, it is sitting at .01/.02, which is to be expected.

My question is, could this be a grounding issue? If not, where would you start first?
Thanks in advance!

mikeynonos · Oct 18, 2021

Anyone.....Bueller....Bueller.....

7991LXnSHO · Oct 18, 2021

Your questions are all over the place, so I have been sorting them out before answering.
A grounding issue would make it harder for electricity to flow any time, not easier when things are shut off.

The amount of amps an amplifier will draw is dependent on the Watts it puts out.
W= A x V so, Watts/12v = possible amp drain from an amp.
Unplug it and see happens to your drain.

What year, engine and model is your Mustang? Someone should have a wiring diagram for your car.

mikeynonos · Oct 18, 2021

7991LXnSHO

Thank you for replying. I have been going through the wiring diagrams, which is how I knew which wires to test. Also, I have no amplifier.

The car is a 1989 Mustang LX 5.0. It has a severe drain on the battery. I have removed the wires from the positive side of the starter solenoid to isolate where the draw is coming from. The 10ga Yellow wire, which feeds the fuel pump, rear widow defrost, fuse panel and ignition switch, when it is attached, makes the DMM read infinite. The same can be said for the blue wire which feeds the EEC power relay. And finally, the 4ga wire going from the solenoid to the starter, has a draw of 0.2.

I have removed the alternator and tested the b/o wires to verify the fusible links are not blown...both show 1.0 ohm. Anther thing that makes me confused is, the alternator which was on the car makes the draw jump all over, so I attached 2 different alternators I have from running 5.0s, and they also make the draw go infinite.

I am in the process now of testing the rest of the wires.

7991LXnSHO · Oct 18, 2021

Hmmm. Time to get my eyes checked.
Over 10 amp draw is a lot of nothing is on.

Mustang5L5 · Oct 18, 2021

DMM reading infinite, do you have it set to amps or resistance? Is that just the DMM's way of showing over 10amps, because there is no such thing as infinit amps.

I suggest isolating the 10G yellow wire. Do you have wiring diagrams?

As you stated, 4 wires come off that yellow wire.

One goes to the fuel pump relay under the seat. Unplug this to isolate.

ANother goes to the rear defrost relay under the driver's side of the dash nea your left leg. Unplug this relay to isolate.

The other two wires do go to fuses. One is fuse #4 (15A) and the other is fuse #1 (15A).

If pull those 2 relays, and 2 fuses, the >10A draw should disappear. At that point reinstall 1 at a time and check to see if it has returned. That will isolate where to go next.

I have the 1989 EVTM if needed and can take screen shots

Mustang5L5 · Oct 18, 2021

ALso, take a total system reading once you solve the 10A draw. Remove one lead off the battery and connect the meter in series and see how much the total draw is. IIRC it should not be that high really. 0.1A or so.

mikeynonos · Oct 18, 2021

Mustang5L5 said:
ALso, take a total system reading once you solve the 10A draw. Remove one lead off the battery and connect the meter in series and see how much the total draw is. IIRC it should not be that high really. 0.1A or so.

Thank you for the reply.

Yes, it is set to amps. When I say infinite, I mean it maxes out the 10a setting of the meter.

That was my plan of attack for tomorrow, with the relays. Same thing for the blue wire from the solenoid, as it goes to the power relay for the EEC. Hopefully I can make some more progress then.

Kid wita 5oh · Oct 19, 2021

mikeynonos said:
Thank you for the reply.

Yes, it is set to amps. When I say infinite, I mean it maxes out the 10a setting of the meter.

That was my plan of attack for tomorrow, with the relays. Same thing for the blue wire from the solenoid, as it goes to the power relay for the EEC. Hopefully I can make some more progress then.

If it's maxing out the 10a scale it's most likely blown the internal fuse(or fuses). Open it up and check them

Noobz347 · Oct 19, 2021

I can pretty much guarantee you that you are not pulling 10 amps at 12 volts through those tiny little wires.

They'd all be lit up like little light bulb filaments and all of your wire insulation would be dripping onto the floor.

Just for a frame of reference, most modern 12v outlets are rated at 6 amps max. In our old cars... Not so much. hehe

mikeynonos · Oct 19, 2021

Noobz347 said:
I can pretty much guarantee you that you are not pulling 10 amps at 12 volts through those tiny little wires.

They'd all be lit up like little light bulb filaments and all of your wire insulation would be dripping onto the floor.

Just for a frame of reference, most modern 12v outlets are rated at 6 amps max. In our old cars... Not so much. hehe

Hi Noobz,

When I connect this wire to the solenoid, my DMM goes from a (0.02 up to a 1. ) It is as almost I was connecting it o a ground, which is why I asked that in my original post, if it could be ground related. The previous shop that worked on this car did some really nice work, but also some real shoddy wiring. I am going through trying to fix as much of this as possible, and hoping I can find the short, or draw, as well.

7991LXnSHO · Oct 19, 2021

mikeynonos said:
Hi Noobz,

When I connect this wire to the solenoid, my DMM goes from a (0.02 up to a 1. ) It is as almost I was connecting it o a ground, which is why I asked that in my original post, if it could be ground related. The previous shop that worked on this car did some really nice work, but also some real shoddy wiring. I am going through trying to fix as much of this as possible, and hoping I can find the short, or draw, as well.

A short to ground (with nothing to make resistance in the circuit) would get the wire very hot, very quickly.
Posts 6 and 7 sound like Mustang5L5 gave you great advice. What happened when you unplugged them, then plugged one item back one at a time?

mikeynonos · Oct 19, 2021

Okay, so after spending much of the day on the car, here is what I have found;

The wiring from the alternator to the starter solenoid was rigged and loose....corrected now.
The wiring for the MSD box was correct, but the connecters were electrical taped and loose.....corrected now also.
Pulled Fuel Pump Relay....No Change.
Pulled Rear Defrost Relay....No Change.
Rechecked fusible links (4) connected to 10ga Yellow wire....Fusible links good.
Tested wiring at alternator according....all pass.
Removed every fuse....DMM shows (1. ), all the y to the left. Out of range?
Installed a new Starter Solenoid I had as a spare....no change.

With the battery connected and I pull the negative cable, I hook up the DMM in between and on 10a setting show 1.- to the left.
Same can be said if I try the positive cable to the positive post.

Checked battery voltage, reads 12.80.
Also, with voltage setting, with negative cable off, i show full voltage between the negative post and cable....same for positive post and cable.

Any other ideas?

7991LXnSHO · Oct 19, 2021

I just re-read the title figured out why I first thought you had an amplifier.

mikeynonos · Oct 19, 2021

7991LXnSHO said:
I just re-read the title figured out why I first thought you had an amplifier.

No worries...I could understand why you thought it...lol

Mustang5L5 · Oct 19, 2021

I’m confused on your 1. Reading.

Can you show a picture of the display on your DMM and the settings the meter is set on?

90sickfox · Oct 19, 2021

The second most common place that causes a draw us the ignition switch.

mikeynonos · Oct 19, 2021

Mustang5L5 said:
I’m confused on your 1. Reading.

Can you show a picture of the display on your DMM and the settings the meter is set on?

I will tomorrow. It is basically the same as "OL", or over-loaded. I also think I may need to try a different DMM.

Kid wita 5oh · Oct 20, 2021

mikeynonos said:
I will tomorrow. It is basically the same as "OL", or over-loaded. I also think I may need to try a different DMM.

Have to checked the internal fuses yet? The meter will do you no good if it's not working

mikeynonos · Oct 20, 2021

Kid wita 5oh said:
Have to checked the internal fuses yet? The meter will do you no good if it's not working

I did check it, but I will double check it to make sure.

Electrical How many amps could an amp draw draw....

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