Hey all, I came across a very unusual situation while trying to diagnose a 1996 es300. After several failed attempts to make connection with my scan tool, I decided to check the DLC fuse 7.5A. Fuse is good, what I did find was the #2 wire that runs from the OBD port to the ECM (white wire) was wrapped with electrical tape. The wrap job didn't look clean, as if it was done in a hurry. I unwrapped it and found two different size wires fused or joined into one. The larger wire (gray) runs back to the harness and the smaller wire (white) connects to the OBD port. The larger gray wire has its outer braided conductor/shield peeled back as if someone did a splice job. The smaller white wire does not have the same.

It seems this is the signal wire, and would explain the connection issues. Anyone familiar with this type of set up and how to correct it? Any help would be greatly appreciated.

 

Hello,

Which pin does this wire connect to?

Well that's weird.. The shielded wire in the picture is definitely not OEM, I am not sure where is it coming from, so you will have to trace it to what would likely be another bad repair.

It appears that the damaged wire is coming from Pin 16 of the OBD2 port, which is a Constant 12V supply. If you can't find the source of the original wire from the fuse box, you will have to wire your own from the OBD fuse.

Hope this helps and best of luck!

 

That could be a shielded antenna wire that happens to run past the OBD port. You don't specify your year, some years have two shielded wires similar to that.

 

Hi, It goes to pin #2. Which based on the wire diagram goes directly to the ECM SDL connection.



I split the larger wire that goes into the harness and the exact wire is buried/lives inside. which means it's an OEM wire. it was tucked in the harness neat with the others. I had to undo it to get length to peel it back. What's odd is, the where the two wire breaks, they were held together with electrical tape. Why would Lexus run a shielded wire and then stop a few inches just before the OBD. Beats me I may have to take a trip to the salvage yard.







My next move is to go to the ECM and check the connection...

 

Hi, I was thinking that also but the way it feeds into the harness and then to the fuse panel...I post some more pics

 

UPDATE ON THIS DLC WIRE:

I found a 1995 es300 at the salvage yard and the DLC wire has the same exact set up. That shielded gray wire with the electrical tape. Maybe it just serves as an insulation, why I don't know. There's continuity at all the wires from connection to connection. I did notice some water rust area on top of the ECM, and the car did leak heavy around the windshield. I will send the ECM to get tested.
Will post once I know more.