Can you bypass the internal with an external regulator. I have low voltage from the ECM. New alt installed. It all stemmed from bad shifting and a bad TC. Checked old alt and voltage was anywhere from 9-14.

99 quad cab 4X4 with a power puck

 

check your grounds make sure there clean also theres a temp sensor under the battery that tells the PCM to lower charge rate could be corroded next I would have the PCM checked if the engines running fine I dont think its the ECM

 

I thought my truck only had an ECM not PCM.?

 

Nope, 24V have both.

 

Ok , it seems to be fixed. New alternator and 140amp fuse in the relay box under the hood was blown. Had to look all over to find one. Test drive and all is well, no hunting for overdrive and originally the TC was locked in OD and it was replaced also. $1200 is still cheaper than a new truck.

 

This fuse blew for a reason. And most likely I know why.

 

Why do you think it blew?

 

voltage is regulated by the pcm not the ecm, and u can bypass it altogether by using an external voltage regulator, use the search function.

 

What I have seen is when the oil filter was cranged the filter wrench accidently touched the alternator battery stud. That will zap the fuse. I have seen it happen 4 to 6 times. When a fuse blows it does not just happen there always is a cause.