chitlah

My first post so please go easy. I have an 07 ML350 that really hasnt had any major issues up until the other day when I went to go get it smogged. The smog place hooked up the car and they told me that the car was not communicating with the smog machine properly. This was never a problem before and i have breezed through a couple of smog checks. So I decided to go to another smog place. Same Deal no communication from obd2 port. I checked ALL of the fuses in the engine the back and the passenger side and all fuses were good. The only thing that I notice that is bad on this car is that the Negative battery terminal is corroded with that white powdery acid stuff. Also next to the battery is a bunch of more electrical and two of the red wires also have that corrosion substance on them. What causes this? Would that be enough to kill my obd2 port? I plug in a icarsoft scanner and it reads some of the modules but none of the major ones that it needs for smog. I am unsure what to do as I do not want to go to dealer and see whats wrong but I have to smog it. There must be a problem with the port itself but i am able to communicate with other modules in the car but only with the icarsoft scanner. Any help on what to look for with this scanner would be great as i just got it yesterday. Thanks for your time and any imput would be wonderful.

chitlah

battery under passenger seat

battery under passenger seat

Maj. Dundee

That is battery acid leakage. Must replace the battery and remove all acid powder with a solution of water and baking soda.

Also check fuses 56 & 58 in the cargo area fuse box.

chitlah

checked both of those fuses and they are good! icarsoft scanner can talk to various modules in the car but i cant get the standard obd2 reader or a smog machine to communicate with it. bizarre!!!

Maj. Dundee

The next step is to go directly to the Data Link Connector.

With the key on and using a DVOM, check pins 8 & 16 for 12v.........and pins 4 & 5 for GROUND.

Make sure you are testing the correct pins by looking at the boxed out section in the PDF.

DansGL

Have you tried your Central gateway module? CGW It merges a bunch of different CANbus signals together. Pop up the panel under your drivers seat and look for a small electrical box. usually grey. Any corrosion or burns?

Good luck!
Dan