OBD2 port and light not working?

MARIO1547

MEMBER
2001 HYUNDAI ELANTRA
2.1L
4 CYL
2WD
AUTOMATIC
265,000 MILES

I think that my check engine light port is not working and that my light is not working either. I mean I do not think the light comes on even though there is a problem that should make the light come on. Can u tell me how to find out if my port has power and how to know if my obd2 is working? There are several electrical problems that my car has had for a while like the radio going back and forth from radio to cd just out of nowhere and the high mounted break light(the third brake light)not working. Also a while back someone riged a cable from my fuse box under the hood to my fuse box under my dashboard, and that made the port start working, but the cable fell off and I do not know which fuse it came from and which one it went to in order to try to re-right. So, I need help to check if my obd2 system is working and to fix it if it is not. And the radio and third brake light too but the obd2 is first priority.

7 Replies

MARIO1547

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5 POSTS

I forgot to mention that for a while there was a small cable under the dash close to the obd2 port, that I used to have to move around and get it in just the right position and that would make both my obd2 port and my radio work.

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Sunday, May 5th, 2024 AT 11:24 AM

KEN L

MASTER CERTIFIED MECHANIC
48,313 POSTS

It sounds like someone did some creative wiring but here is a guide to help you test for power and ground of the data port. Also, when you turn the key on without starting the engine does the check engine light come on?

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Here is the port wiring diagram so you can see how the system works. Please test the red wire for power and the black wire for ground. Check out the images (below). Let us know how it goes. Also check the fuse #25 in the fuse panel inside the car.

Image (Click to make bigger)

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Monday, May 6th, 2024 AT 11:38 AM

MARIO1547

MEMBER
5 POSTS

Hi Ken,

Sorry for my late response. I checked the wires and the fuse, and they are good. And the check engine light does come on with key in on position.

Also, recently I had a check engine light come on for two days and then turn off. And also, recently I had to change the camshaft sensor but I never received a check engine light for that.

Also, while checking the fuses, I checked fuses #5, 9&18 (ac sw, audio and c/light) for ground and they were showing a dim light. And I think they are related because my ac, audio and high mounted break light have problems. Could probably be something else but I thought I would mention it.

Please let me know what I can do next to fix this problem.

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Thursday, June 6th, 2024 AT 4:52 PM

MARIO1547

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5 POSTS

One more thing is that the rig job that was done before to the port had a yellow cable that was cut on the end down by the port and the other end goes to fuse #13(RR HTR) under dashboard. And then the yellow cable continued to the fuse box under the hood. Just thought I would mention it.

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Thursday, June 6th, 2024 AT 6:29 PM

KEN L

MASTER CERTIFIED MECHANIC
48,313 POSTS

Can you please check to see if the red wire going to the OBD2 connector has power and if so, please check the black wire for ground, this guide can show you how:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Does it look like the wiring has been cut or damaged?