Ignition woes. My mechanic sez................

[MadMike]

I would find out why your electrical system may be having 'spikes' and killing electronics.

Verify the battery is clean(no spilled acid/gunk on the batt or batt tray), holds a charge, and is properly secured to the tray/truck.
Verify your battery connections are clean and tight, no corrosion on the terminals or in the wire connections.
Verify your engine and body grounds/bonds are clean and tight as well.
Verify the alternator to voltage regulator harness is not corroded/damaged, terminals inside the plastic flat connector tend to corrode, cut off and install new female spade connectors on clean wire. Same with the eyelet connectors on the alternator, they tend to corrode as well, clean up and/or replace where needed.
Verify the wire harness to the starter solenoid has a clean/tight/corrosion free connection.
Verify running voltage, and running voltage with all accessories on(lights/fan/radio).

Electrical system on these trucks is very simple, but if someone has hacked or added accessories without using the existing accessory electrical circuits this may cause backfeed or other undesired affects on the electrical system.