Back story. 99 drive train and wiring, 5 year old MSlabs MS2 .

Dyno tuned my car the weekend before going to the track and had no issues. While driving off the trailer and to tech there was no issues. Saturday morning I started the car to warm up and about 2 minutes later realised something was wrong. Battery light came on so I killed it. Minute later the battery started smoking as the lithium had popped and a small fire started. Replaced the battery with normal one from NAPA and restarted the car but battery light stayed on. check voltage and it was 17v so weekend is over before it started.

Fast forward MS2 is bed and I replaced it with a MSPNP. Not sure if the ECU going bad caused the over volt or if the over volt caused the ECU to go bad.

My paranoid personality wants to make sure that I'm covered in case the ECU going bad was not the cause of the alternator outputting 17v as in the NBs the alternator controls output voltage. I don't want to crack the car with a brand new MSPNP and have it fry.

What can I do to safe guard my new ECU? Thinking a inline fuse but don't know the size or where to wire it in.

Stock ECU is not an option, no MAF, big injectors, blower, no idle air, ect.

 

You could do an NA alternator swap and adjust the wiring to match if you're really concerned about using ECU control.

Is the car an NB?

 

All 99 parts. I'm not concerned about the ECU controlling alt, I'm concerned about hooking up a new ECU and blowing it up. I am not sure if the old ECU failed first causing the alt to keep making all the power it could or if something else caused it and the extra power killed the ECU.