Originally Posted by Trojan Horse
Use a diagram to figure out which relay it is in the CCRM and which wires you need to test.
Fuel pump relay diagnostics:
First, always check the inertia switch in the trunk and the fuel pump fuse in the underhood fuse box (20 amps). Also check the ignition switch fuses. With the key turned to run and checking within the fuel pump prime-out period (a duration of 2-5 seconds after turning the key to run): Check CCRM pin 5 for accessory 12 volts. If you have it, the issue lies downstream. If not: Check CCRM Pin 11 for constant 12 volts. Check CCRM Pin 13 for accessory 12 volts. Check CCRM Pin 18 for a ground signal during the prime-out.
If this is all good, check the inertia switch (located in the driver side trunk, adjacent the tail light) and fuel pump electrical connector at the tank.
If I'm not getting 12v on pin 5 does that mean the problem is upstream? God, I hate electrical problems!