No power to OBD port

I was trying to adjust the tune on my 99 Cobra today but when I plug my tuner (sct sf3) in to the OBD port it won't turn on. From what I've read, it could be a blown fuse so I replaced my cigarette lighter fuse but it still isn't working. I know the tuner works because when its plugged into my computer it turns on just fine, but when plugged into the car I get nothing. Does anyone know if there's another fuse I could check, or is there another common issue that could be causing it? Any help is appreciated

Check fuse 31 (10A) in the fuse box on drivers side. I think DLC has its own fuse. If that doesn’t work try plugging something else to DLC to verify it’s not the tuner.

Or plug the tuner into another car to make sure it's not the cable.

JaCobro said:

Check fuse 31 (10A) in the fuse box on drivers side. I think DLC has its own fuse. If that doesn’t work try plugging something else to DLC to verify it’s not the tuner.

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Checked that fuse, it's perfectly fine so I'm gonna test the tuner on another car to see if the cable is possibly messed up

Update

I tested the tuner on another car and it booted right up so its definitely an issue with the car and not the tuner. At this point I'm stumped

Do you have anything pulling power from your fuse box under the dash? Something like an add a fuse or wideband?


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I would suggest you get a magnifying glass and see if any pins are bent or perhaps pushed out of the back of the port.

Yeah. Like fitforspeed said check for any devices pulling power at fuse box. If all good there. Visually check for damaged pins at dlc or damaged wires. A good flash light will help too. If all good there. Pull out the volt/ohm meter and check pin 16 for more than 10 volts power. If all good there. Check ground pins 4 and 5 for less the 5 ohms of resistance. Doing this should help locate the problem.

99% of the time its a popped fuse

pull it and swap it regardless

On

JaCobro said:

Yeah. Like fitforspeed said check for any devices pulling power at fuse box. If all good there. Visually check for damaged pins at dlc or damaged wires. A good flash light will help too. If all good there. Pull out the volt/ohm meter and check pin 16 for more than 10 volts power. If all good there. Check ground pins 4 and 5 for less the 5 ohms of resistance. Doing this should help locate the problem.

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The car is pretty much stock, has a built motor but nothing extra that could be pulling power. I'll check the wiring and pins later when I get a chance, and then if that's good I'll check the voltage. Thanks for the help

I pulled the fuses and they looked perfect, I swapped new ones in and it had no effect just to be sure. I wish it had just been that

decipha said:

99% of the time its a popped fuse

pull it and swap it regardless

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If memory serves its pin13 on the port that gets the 12v signal. Make sure nothing is popped out or loose in the harness.

Quick update:

Plugged in a cheap code reader and it powered up but was having issues scanning for codes, so the port is getting some power. Then I checked pins 4/5 and got 4.5/8.5 ohms, and then checked pin 16 and it was varying in voltage all the way from 5 to 12 volts.

nowak98 said:

Quick update:

Plugged in a cheap code reader and it powered up but was having issues scanning for codes, so the port is getting some power. Then I checked pins 4/5 and got 4.5/8.5 ohms, and then checked pin 16 and it was varying in voltage all the way from 5 to 12 volts.

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I’d make sure wire and pin has a good connection on pin 16. Then trace wire till you get a solid 10-12 volts of power. A solid volt meter matters too.