Ford Mustang Forums banner

Multimeter Weirdness

1K views 16 replies 3 participants last post by  indy2000 
#1 ·
Still trying to figure out why my car won't start after it sits for a few days.

I have a video here



I'm not sure if this current draw is enough to kill the battery... not sure why it starts high and then slowly goes down (it would go down to zero if I waited long enough).

The second part is another car I have. It has the same behavior... except it starts very high and then quickly goes down to zero.

I've tried this on two different multimeters and it's the same behavior on both.

So what causes this?

Is this normal?

Is that enough amp draw in the first video to make a battery die after a few days?

If not could it be something else... solenoid?

Thanks for any help.
 
See less See more
#3 ·
You can use a hose clamp around the terminal to hold the multimeter lead if you are doing long term testing. The reason it jumps up is because when you first add power anything that uses constant memory power will charge up capacitors and things like that. Once all of that is charged up then you will see what the actual draw is. Like Indy said, hook up the meter first.. I would wait a few seconds to allow everything to stabilize before turning it on.
 
#5 ·
.15 amps is a really low draw. It would take significant time for that to drain your battery. Typical stock battery has about 450-600 CCA. It would take quite a long time to bring that down.
 
#6 ·
So it turns out that it likely isn't the battery at all.

Did the draw test, made sure the battery was good, took it up to the local AutoZone to test as well just to make sure my Sun reader was correct and it was.

Went to turn over the car to test alternator output and it wouldn't start!

So I knew it wasn't the battery at that point.

My first thought was the safety clutch switch or the solenoid. Since it's so easy to check the solenoid on these cars I did that and I'm thinking I FINALLY found it.

First couple tries jumping the solenoid and it wouldn't turn over. Just clicked a few times. Then after the third try it finally cranked.

It's the original solenoid so I'm guessing it just finally gave up the ghost.

Fortunately found a Motorcraft replacement. I was surprised I could find one and that it wasn't 150 bucks or something from someone's stash :)
 
#8 ·
Because I have no idea how to do that.

I really REALLY hate electrical crap. I mean REALLY hate it.

I got a new solenoid and the damn thing shorted out!

Hooked the wires up exactly the same and the damn thing had sparks flying all over the friggin place!

Took it off, hooked the old one back up the same way and no sparks at all.

Original part number is

E9TF-11450-AA

The one I got from LMR which is SUPPOSED to be the same or equivalent is:

E9TZ-11450-B

So at this point I have no idea what to do.

Probably going to just give up and set the car on fire and call it day.
 
#9 ·
What are the chances that the new part is defective, I say near zero

what are the chances that you misdiagnosed and you have a wiring problem, i say near 100%

your options

learn basic electrical, because that is all you need for automotive purposes

take it to a shop that will do the work for you


what says you?
 
#10 ·
I took it to a shop because it scared the crap out of me when it was shooting sparks.

I was afraid I was going to catch the damn car on fire.

Turned out to be the starter. Which I had ruled out since I replaced it last year.

Lasted just long enough for the Autozone warranty to run out.

One of the things that's a pain with these cars... finding quality parts.
 
#15 ·
It gets switched power, or straight power

Unless upgraded its the old ‘gets switch power’

If so, then the starter could not be the issue, as it receives load power from the solenoid, unlike the newer style that gets control power to hot solenoid on the starter itself.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top