OBD connector has no power when plugged in

GP2

MEMBER
2009 TOYOTA MATRIX
2.4L
4 CYL
2WD
AUTOMATIC
140,000 MILES

I have the vehicle listed above S that I purchased and it had been in a small fender bender but nothing major. I tried to start it and it attempted to crank but it won't start. When I tried to check the obd reader to see if it had any codes, it wouldn't turn on at all. I checked to make sure the pins behind the obd port to make sure they were not corroded and I also tightened the ones that were a bit loose and pressed on the folded part of the pin to close them in more in case the pins weren't getting enough contact from the obd readers. I checked all the fuses to see if any of them were blown and all of them were good. I also tested the relays under the hood and inside under the steering wheel. I then checked to see if the obd port was getting power and it was but only 4.5 volts. I know it's supposed to have a constant of 12-volts but it doesn't. I've changed the battery to see if that was the cause but no luck. I tried unplugging all the wiring connectors and relay and putting them back in to see if that would do anything and still no change. I also checked some of the ground connections that I could find near the battery cables and sanded them a little to make sure they weren't dirty or corroded. I started to test some of the different wires coming from the engine and found this one above the pink 30 A with three wires going into it. From testing it by chance I found if I have the obd reader plugged in when I have a fuse tester grounded and touch the red power cable with the pin directly below it. It powers the obd reader on if I hold a grounded metal touching the red cable and the pin directly below it. But even when it powers the obd reader it still says on there to check the connection to make sure obd connection is good and to make sure the ignitions is not on. Then after scrolling down, it still says unable to establish a secure connection. I'm at a loss as to what it could be. If anyone has any advice or solutions as to what it could be it would be greatly appreciated. Thanks

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5 Replies

KASEKENNY

MECHANIC
18,907 POSTS

You are correct. You should be getting a constant 12 volts to the DLC on pin 16 which is a light green wire. If you do not have 12 volts here, then we need to start with this. If you only have 4.5 volts on this wire, then that is our issue to start with.

However, we need to confirm which wire you tested when you had 4.5volts.

See the wiring diagram below but once we get power to the DLC on this wire and confirm both grounds are good by using both 4 and 5 to check for 12 volts a known good 12-volt source like the battery.

https://www.2carpros.com/articles/how-to-check-wiring

Once the scan tool powers on from this source, we will need to move onto the communication issue. You have what is called a CAN bus system and this is how the modules communicate with the scan tool, so I suspect we have a connector issue causing all these issues.

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

So, if you are powering the OBD connector and still not getting communication then we need to trace the wiring and find out if we have a connector issue causing all these issues.

Please see the wiring diagram and let me know what you find with this.

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Tuesday, May 17th, 2022 AT 7:26 AM

GP2

MEMBER
3 POSTS

Hey Kenny, So, after doing some further research and going off the information you gave me. I had already checked all the fuses and relays and they were all good. The one thing I read that sometimes could be the cause of the loss of power to the OBD port and in some cases not even charge the battery was a blown fuse link. So just by looking at it from up top I couldn't tell so I unscrewed all the wires off of it and out of the fuse panel to further inspect it. After removing the clear plastic cover and looking at it closely I was able to find where it had blow it had gotten blown/separated at the very beginning and unless I had removed it I never would have been able to tell. So went to the junk yard and was able to find a similar make and model of the exact same fuse link and replaced it and now I finally had power to the port a constant 12v on pin 16. I read that sometimes the only way it's blown is crossing the jumper cables the wrong way.

After I plugged in the scanner, and it had power and it was attempting to connect but kept giving me the error "Tester not communicating with control unit". Another odd thing I noticed was that even before I swapped the fuse link I had made a video and noticed that even in the on position the check engine light would illuminate even before attempting to try and start the car.

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Saturday, May 28th, 2022 AT 9:37 PM

KASEKENNY

MECHANIC
18,907 POSTS

Okay. That is great. Good job making this progress.

However, now that you are here and getting this lack of communication with the PCM and you had this blown fusible link it sounds like we may have something greater going on.

Is there any chance that this was struck by lightning, or the battery cables were hooked up backwards?

It sounds like with a blown link and a PCM that is not communicating that we had a power surge that may have damaged a number of things.

Inspect the tip of the antenna and see if it is black or melted at all. This would indicate a lightning strike.

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Sunday, May 29th, 2022 AT 7:08 AM

GP2

MEMBER
3 POSTS

I decided to try and see if the communication issue was due to a bad ECM. So, I got a similar model from a used parts store and did the re-set of the ECM by putting a paperclip in the OBD port on pins 4 and 13 and letting the car stay like that for 30 minutes and then removing the paperclip and then tried starting it and it started up. Now my only issue is that the Speedometer gauges don't work and move, and the electric steering is not working the car runs and drives fine it's just the steering is very hard to turn, and gauges don show how much RPMs you give it gas or how fast you're going. The OBD port still shows the linking error, but the car starts and runs.
Any ideas?

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Sunday, September 4th, 2022 AT 8:49 PM

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

It sounds like the ECM has not been programmed correctly. Let's run the CAN scan codes to see what comes up which is easy, you can get a CAN scanner from Amazon for about $30.00.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

Here is a scanner link:

https://amzn.to/3o41KcZ

Let me know what you find out.