There is no power at the OBD II port

  • 1997 DODGE RAM
  • 5.2L
  • 4WD
  • 100,000 MILES
I've tried 2 different OBD II readers and they don't power on. I've checked the fuses in the cab and none are blown. The wire harness under the dash looks in tact but the harness goes through the fire wall to behind the engine so that's where I can't follow it. The repair manual (Hanes) I have just says to check for fuses but I don't see one in engine dept. There's an aluminum block on the passenger side on the fire wall with a lot of wires connected to it so I guess that's the engine computer. Everything looks good their. Any suggestions?
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Saturday, October 31st, 2020 AT 10:55 PM

1 Reply

There is a power distribution box under the hood with the relays in it and those power the interior fuse box as well as other systems. Fuse 9 in the interior fuse block powers the diagnostic connector as well as the ASD relay so if the truck runs that fuse is okay. There is also the ground for the DLC in pin 5 if that is bad then you wouldn't have power for the tool either. To test the fuses and the DLC power and grounds a simple test light will work.

Use it first to check all of the fuses with the key on. a fuse can look good but still be bad.

Then use it to test the data link connector. Pins 4 and 5 should be grounds and pin 16 should be power.
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Sunday, November 1st, 2020 AT 2:49 AM

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