Fox Random spike voltage (Need help from scope users)

[martroy]

Hi everyone,

I'm chasing random voltage drop and would like to have help from scope users to see if the following behavior is normal.

When scoping battery voltage on post (yellow line) against pin 37 at EEC 60 pins connectors (blue line) when engine is running, I do have spike from pin 37.
When scoping battery voltage on alternator post (yellow line) against pin 37 at EEC 60 pins connectors (blue line) when engine is running, I get spike on both of them. It is normal to get this?

It's a brand new 3G alternator.

Any help would be appreciate. Thank you

 

[Noobz347]

Any alternator is going show spikes 180 degrees apart.

What issue are you chasing or is this just, "gee wiz"?

 

[martroy]

Chasing random drop spike voltage and wondering if its normal a different reading from a different location. Alternator stud vs battery stud. All ground were verified.

 

[General karthief]

What is the issue that prompted you to measure voltage there?
As far as I understand drop in voltage can be a loose/corroded connection or stressed wire.

 

[nickyb]

Houston do we have a problem?

 

[AeroCoupe]

I think this one is landing in FLOR I DUH.

 

[martroy]

What is the issue that prompted you to measure voltage there?
As far as I understand drop in voltage can be a loose/corroded connection or stressed wire.

Here's what I'm trying to find out the root cause of this.

When running without any specific behavior, it was registered in my logs (Megasquirt) voltage 14,5 to 14,0 for a split second. At first, I tought it was a MS issue but it's not since I do see the same outside of logs.

Now, basic stuff done like cable connection, ground, rust, bolt and found nothing really important for now.

Since scope seems a good tool to find out those thing that happens fast, I purchased one. (I'm new to this).

So my first question was is normal to see spike like this on the alternator stud compare to battery itself?

Thank you

 

[General karthief]

I got nothin for ya on the scope thing without being there

 

[AeroCoupe]

Are you sure the voltage regulator is not the issue?

 

[martroy]

I changed my alternator cause I had a bad rectifier and now, this one is brand new.