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Does the starter relay in the underhood junction block click at all when you turn the key to START? If not, pull the relay out and then verify the continuity to ground at socket for relay terminal 86. Next, get a helper turn the key to START and then verify 12V or higher at the socket for relay terminal 85. The voltage there comes from the 20A IGN C fuse, through the ignition switch, 10A CRANK fuse, and then PNP switch (closed with shift lever in P
). Backtrack until the culprit is found (jiggle and move the shift lever, check the voltage at the CRANK fuse, etc.).