i have a 88 ranger that when u plug in the test code it will not read without grounding the fuel pump relay plug. i have 12v at the top pin,if you jump this pin to the pin just below it the high voulme pump kick in but the in tank willnot . when you ground the far left pin the tester will give these codes 21 24 67 52 87? 87 being fuel pump cir. failure? have i got a ground problem in the wiring harness?