2007 Saturn Aura XE 3.5L and the OBD2 port is not working. My daughter was unable to get her car inspected because the garage couldn't connect to her ECM. I've tried my scan tool, and the same, unable to connect. I've checked the fuses. I'm assuming there's a bad sensor that is preventing any sort of scan. My scan tool works fine on other GM and Ford vehicles and connects in seconds. Any ideas where to start?

edit/update:
The scan tool will not connect to the ECM/ECU. I see the tool scanning protocols with the ignition on in accessory mode. I see the lights on the scanner, so power is present. I disconnected a bunch of sensors and connectors and cleaned all the connections with electronics cleaner. I cleaned the OBD2 port. No luck. I've checked the OBD2 port pins and tried a brand-new obd2 extension cable. On the ECM next to the battery, I disconnected and reconnected the two big connectors. They were clean and corrosion-free. I reviewed the fuses & fuse box, etc. The car is showing a traction control light, but that's been on for a while. I do hear clicking from time to time from the transmission area, so there's likely a bad sensor of some sort. I did remove and clean the big connector on top of the transmission. It was nighttime, so I didn't climb under the car. In my state to get an inspection the mechanic has to connect a special tool to the obd2 port and run through the process, read the vin, etc.

 

There are several things that may cause the OBD2 port to not function correctly. Let's start with a picture of the port for pin numbering and a definition of what each of the 16 wires does.


OBD2 port pin numbering

OBD2 **** pin function

1. If your scanner is unable to negotiate a connection to the OBD2 connector / DLC, it is possible that one or more of the pins associated with
   1. battery voltage
   2. High speed GMLAN
   3. Low speed GMLAN
   4. Class 2 Serial Data
   5. Ground

Are not making good connection with the scanner port and therefore the signal is not getting to your scanner.

It is not uncommon for one of the pin socket receivers to get pushed back into the back of its slot and therefore not make contact when the reader is attached to the port.

Shine a flashlight directly parallel to the Pin sockets to see if any of the sockets have been pushed back compared to the others.

If so, reach behind the connector and determine if the wire leading to that socket number is loose or can be adjusted position wise to bring the location of that socket forward to match the others.

Do not insert anything into the socket to try to pull the socket forward.

Double check that your scanner plug does not have any bent pins. Straighten them very gently if they are.

If you've had to move a wire to get the socket receiving contact forward, hold that wire in place and gently insert your code reader plug. Do it very slowly and pay attention to any resistance to plugging in and seating all the way.

Your scanners should be set up for auto protocol and should be able to successfully determine the correct protocol.

You can also check the pins labeled as ground vs chassis ground.

If you cannot find a terminal that has been shoved back, you will likely need to take your car to a mechanic to determine which connection is bad and or which communication network is being problematic.

Never try to jam a multimeter probe into an OBD2 socket. It bends the receiving clip and after you remove it, it may not be tight enough to properly contact the reader's pin.

 

[QUOTE=mitchd123;71305]2007 Saturn Aura XE 3.5L and the OBD2 port is not working. My daughter was unable to get her car inspected because the garage couldn't connect to her ECM. I've tried my scan tool, and the same, unable to connect. I've checked the fuses. I'm assuming there's a bad sensor that is preventing any sort of scan. My scan tool works fine on other GM and Ford vehicles and connects in seconds. Any ideas where to start?

Your scan tool will NOT access the OBD in the accessory position. It needs to be in the START position. Try that and post back.

 

@derf , thank you! I will give the port itself a deeper dive when I have the car again. Using my multimeter I will check the OBD2 port for missing/pushed pins, as well as ground resistance and correct positive voltage.

@Rubehayseed thank you also! I said accessory, I did mean the run/start position. I tried it with the engine off in the run/start position and even with the engine running.

I feel bad for my daughter, the car has only 105k miles. Not bad for a 2007.

Under the hood the black plastic split wire loom tubing plastic has pretty much deteriorated and is crumbling away in much of the engine compartment. This must have been defective from GM, because even touching it slightly causes it to crumble. I did check the harness that I could see. There was some slight copper exposure where the wire harness crosses the fuel line in the engine compartment. I separated the wires in the harness, carefully inspected them, and put some electrical tape over the one wire whose insulation was damaged. I then enclosed that rub point where I taped in a rubber hose to protect it. While the wire showed some copper, the copper core was not compromised or broken in any way at the touch point. There could be another touch point somewhere that is not visible. Fuses have all been checked for continuity with a multimeter.

 

I'm terrible with electrical work, so will leave this to my buddy derf to help you figure out. Maybe Andy or Billy can help as to be perfectly honest, I've never even looked under the hood on an Aura.

 

Thanks for posting. I'm still unable to get the OBD2 port to read. She can't get it state-inspected, because the state-required instrumentation won't connect to the car. Without inspection, registration get pulled, etc.

I pulled apart the OBD2 port and checked all the wires and leads. It won't work on my scanner, nor the one at Firestone (inspection station)

The voltages were as follows:

With the car running:
Between Ports 4 (Ground) & 16 (Battery Positive) =13.6V
Between 4(Ground) & 14 (Can Low) =2.37V
Between 4(Ground) & 1 (Low Speed GM Lan) =.4V
Between 4(Ground) & 6 (High Speed GM Lan / Can High) =2.6V

Not sure if any of these look out of the ordinary? The Can numbers were floating around, but I recorded the most prevalent values.


#OBD2 Unable to Connect

 

Sounds like all the pins are at least active so to speak. I'm guessing that the portion of the can Network the port is on is having a problem. As in something is perturbing the traffic being sent from module to module or shall we say controller to controller.

You are going to need a schematic that shows what modules are on what branches of different can networks within the vehicle.

It's possible that your traction control module is on the same branch of the can Network as is the port. Depending on what's wrong with what, and how, different modules on a can Network can hose just themselves or also may hose additional modules or even an entire branch.

Did you ever pull the code associated with the traction control light? It would likely be a code starting with the letter B.

We have very few aura folks that come through here.

You may wish to try posting on saturnfans.com

They have many many many more members and many more regulars so they are more likely to have the diagram you need to solve this.

 

@derf Thank you VERY much for your reply and suggestion to try the other forum. To answer your question, unable to pull any codes w/o the OBD2 port working. Unless there's a different way to pull the traction control codes. I do suspect that some branch on the can network or sensor is shorted or screaming, and interfering with traffic on the network.

In the other forum you suggested I saw a post that talked about an aftermarket radio causing the OBD2 port not to read. Could that even be possible? The factory radio has been removed from this car. I would think if this was the case, there would be thousands of people with the problem and not just a few posts across the internet.