mystery wire near battery terminal

[calsbeek]

My BJ74 (13-BT) has developed a labored startup with a cold engine. After digging around under the hood, I found this wire, not connected to anything, which goes through the fire wall on the passenger side of the vehicle. Any idea what it is and whether it should be connected somewhere?

 

[cruiserdan]

A single wire transiting the firewall is NOT factory. It is likely an added power feed to a DC/DC converter to run 12 volt accessories.

 

[calsbeek]

Hmmm ok. no other suspicious wires that I can see. All grounds look good.... any other thoughts on why I'm having rough starts?

The battery level indicator also shows low when I first start the truck but then climbs to full after a minute or so....

 

[cruiserdan]

The volt meter operation is normal. The charging circuit is basically suspended for the first ~70 seconds of cold engine operation to keep the cycling manifold heater from causing voltage spikes.

The pre-heat "glow" function does not come into play until ambient temps are below ~25 degrees F. 13BTs do not like to start easily between ~25 degrees F and ~45 degrees F. That range is a bit too cold for easy unaided starts but not cold enough to activate the glow circuit.