On the 2003 Ford F150, if you plug your code reader or scan-tool into the Diagnostic Connector and the scan-tool or reader will not turn on or read any p-codes, the Diagnostic Connector is on the same circuit as the Cigar Lighter. This is fuse number “F2.3” in the fuse box located under the driver’s side dash. If the fuse blows after replacement, then the problem will be in the Cigar Lighter receptacle. Remove the lighter assembly and make sure there are no broken or damaged wires. If the visual inspection checks ok, replace the Cigar Lighter receptacle and then a new fuse.
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