First time post. Been doing a lot of reading but getting to the end of my rope.

The truck is a 2003 QC 4.7, keyless, auto, middle of the road truck. Back in December, the alternator failed. Replaced with a unit from Advance Auto, dealer installed and said everything checked out okay. Fast forward a couple of weeks and went to start the truck. Indicators came on but no reading on the volt meter, turn the key to start, nothing (does not crank, buzz.....). Turn the truck off and go to start again. Nothing. 3rd times a charm, starts runs normal. Fast forward 2 months, does it again. Goes a week, does it a third time. Then it decides to go low voltage reading. Shut truck off, starts right up, runs fine for 3 weeks. Today, voltmeter is pegged high. Quick pull over, grab the multimeter and check voltage with truck running. 14.8V. Get to destination. Turn truck off. Restarts just fine and has a normal voltage reading. I have cleaned some grounding points but I am at a loss. Any ideas? Thank you in advance.

 

are you throwing any codes?

 

None. The high voltage shows on the odometer but no MIL.

 

have you checked other grounds?

 

I cleaned battery to ground. I cleaned PCM to ground. I ran secondary grounding straps from PCM to firewall. I would like to replace the original straps from PCM to block and firewall to block.

 

Just an update. During the last no start issue, I waited for a while with the key on and the truck finally said no bus. Any thoughts on an intermittent no bus? No more over voltage spikes but the truck now shows 14.3V when running.