Rick's Free Auto Repair Advice

Ford F150 Dead battery in morning

Diagnose and fix Ford F150 dead battery

Many owners may find a situation where they have Ford F150 Dead battery in morning condition. This can be caused by many things so you have to go through a process of elimination. Start by checking the condition of the battery using a load tester that also measures resistance and conductance. If the battery passes that test. Go on to conducting a battery draw test shown here.

Parasitic battery draw test

Using an inductive low amp probe, check for current draw with the key off and modules in sleep mode. Turn off all power accessories and close the doors. Wait up to 45 mins for all modules to go into sleep mode.

It’s typical to see current draw in the 200-mA to 400mA range immediately after shutting off the engine. But after 45 minutes, current draw should fall below 50mA. If the current draw remains above 50mA, start by disconnecting the electrical connector from the alternator. If the current draw falls below 50mA, suspect and alternator or wiring harness problem. If the draw stays high, check for corrosion in connector C405 located towards the rear of the vehicle under the tailgate.

Corrosion in connector C405

Many shops are finding corrosion in connector C405 that causes a corrosion in Connector C405current draw and dead battery in morning problem. Leave your current probe in place and disconnect the two halves of C405. If current draw drop and the connector is corroded, you may have found your problem.

Clean corrosion in connector C405

If you find green corrosion in connector C405, use a contact cleaning solution to remove the oxidation and a small brush to clean. Apply a light film of dielectric grease and reconnect. Wait for the modules to time out in sleep mode and check again for current draw. If it’s below 50mA, you’ve fixed the problem.

If current draw is still high, remove fuses one at a time to isolate the circuit that’s drawing power.

©, 2019 Rick Muscoplat

Posted on by Rick Muscoplat

Custom Wordpress Website created by Wizzy Wig Web Design, Minneapolis MN