Has anyone had a problem with the fuel pump shut off switch in their ranger? I have a 2004 extra cab 4.0 4x4 that has the switch shut off after parking the truck on an incline. I am going to replace the switch and noticed that the pigtail that connects to the harness in the truck, gets hot when the truck is running, so hot that the connector is melted into a blob of plastic. The wires on the truck harness are burned and now missing all the insulation. Any advise? I ordered a new switch, and was just going to cut off the melted connector and connect directly to the short harness that connects directly to the shut off switch. I am a bit worried since the old connector was getting hot enough to melt plastic.
Just replacing the damaged connector & wiring isn't likely to fix the problem. Something is causing the circuit to draw too much current for the wire gauge size.
So, a voltage drop from the under hood fuel pump power relay to the inertia switch, to the fuel pump, caused by corroded connections & or wiring insulation damage to the fuel pump all the way from the under hood fuel pump power relay to the in cabin inertia switch & from there to the fuel pump belong on your suspect list, as well as a clogged up fuel filter or fuel pump sock/pre-filter, causing the fuel pump to work too hard & draw too much current, also belong on your suspect list.
So maybe after repairing the damaged wiring & connector, begin your trouble shoot by checking for under load voltage drop at the under hood power distribution box fuel pump power relay connections & at the in cabin inertia switch connections, when you go to KOEO & the fuel pump runs for its 2 second prime. If you then still have a voltage drop to the fuel pump at the inertia switch, inspect the wiring & electrical connections from the inertia switch to the fuel pump. If you know the wiring & connections to the fuel pump are ok, suspect a fuel pump problem.
The under hood fuel pump power relay pin/socket connections have been found to sometimes corrode & cause a high resistance that'll cause an under load voltage drop to the fuel pump.
Anywhere a wire lays in contact with something hot, that vibrates, or passes through a bulkhead/firewall, also belong on your suspect list for insulation damage, especially if the wire has been hot from carrying too much current from a circuit overload.
Some trouble shooting thoughts for consideration, keep us posted on your findings.