YJ - spark alternator = kill computer ?

[cj5wagomando]

I know this is xj country but as well as my xj my son has a yj. A 92 yj with 2.5 liter 4cyl.

He sparked the batt lead while removing a failed oil sender and it seems may have harmed something.

The alt seems to be putting out excessive voltage that is not reaching the battery. The batt lead on the back of the alt has no voltage when not running.

I thought I would post the question of if a quick spark from a wrench to the batt lead on the alt may have done real damage?

thanks,

Dave

 

[x99j]

Re: spark alternator = kill computer ?

check the big fuses in the pdc. mike

 

[Milford Cubicle II]

Re: spark alternator = kill computer ?

What do you mean by "the alt seems to be putting out excessive voltage that is not reaching the battery?" What leads you to think this?

And the lead to the alternator from the battery should be just a heavy gauge cable that connects them directly, if there's no voltage there then check for a bad connection at one end or another. Could be loose or corroded.

Also, check that the alternator is well grounded. Also check for any voltage between the outside of the alternator (the "housing") and a known ground while running.

The first thing I would do is figure out why no voltage is getting to the alternator lug.

 

[cj5wagomando]

Re: spark alternator = kill computer ?

My digital volt meter tells me 33volts at the batt lead at back of alt when running. dead when turned off. All the maxi fuses all look fine. I tried following the wire but had to quit last night.

Looks like the batt lead goes from the back of alt -across firewall to the computer and then back to the battery. It is acting like a fusable link on that wire but my Chiltons shows nothing.

Grounds are fine at firewall and at alternator. as well, the alternator is new out of box two days ago. Battery is new and has a full charge.

The alternator is working hard but the current is not reaching the batt?

darn computers....

 

[cj5wagomando]

upon reinspection in better light (full sun) I found two blown 50amp maxi fuses that are on the alt charging circuit. I will replace those later and tell my son not to try to wire his stereo without some supervision.

I doubt a quick wrench arc to the batt post on back of alt would blow both thes maxi fuses.

Dave.

 

[ktwalker01]

those fuses can blow in a millisecond.

 

[cj5wagomando]

hmmm. maybe for 5 bucks it would be worth it to spark the alt again and see if they blow so I can determine what exactly he has going on there...
.

D