LX450 No Communication to ECM but engine runs

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So I went on another 10-15 mile drive after finishing the interior and putting everything back in. I again got the o/d off blinking. Went to scan and dammit I can no longer communicate with the ecu to read possible transmission codes.... Almost had a meltdown down but thought to myself, what has changed since I installed the other ecu and was able to communicate with it? The answer is I had the wiring and ecu sitting on the passenger floor when I plugged it in. What changed was me installing it back behind the glove box. I'm sure you all know how bent up that harness is when the ecu is back bolted up. So I removed it and started wiggling the wires and regained communication! Probably was this issue the whole time but nice to know I have a spare ecu just in case. The problem now is finding the specific wire that is the culprit.

Can I assume the "SDL" wire from the dlc going into the ecu would be to blame and focus on it? Maybe ground for the ecu? Loose pins in the connector for the ecu? Again the vehicle runs great, I haven't noticed any symptoms besides the "o/d off" blinking around 10 miles into the drive. I figured this could also just be from the wiring issues as well. When I do gain communication, there are zero codes present. No pending, history, nothing. Should I focus around transmission wires from the ecu too maybe? Anyone have a spare wiring harness they want to get rid of? 😁

Any ideas would be appreciated! ✌️
 
AndoFZJ said:
Any ideas would be appreciated! ✌️
Click to expand...
This has been discussed several times in the past and was one of the very first things I did when I got my LX450 home.
The ECU harness runs along the bottom metal support for the lower dash behind the glovebox. This is a common chafe point.
I wrapped the harness and added a section of wire insulation along that lower support.
Good for the foreseeable future.
 
If it were the ecu ground you would most definitely have other running symptoms
 
jonheld said:
This has been discussed several times in the past and was one of the very first things I did when I got my LX450 home.
The ECU harness runs along the bottom metal support for the lower dash behind the glovebox. This is a common chafe point.
I wrapped the harness and added a section of wire insulation along that lower support.
Good for the foreseeable future.
Click to expand...
I pulled all the tape off as far up into the dash as I could. I haven't found any physical damage or chafing on any wire insulation. Maybe I will remove the harness thru the firewall and look further. When I had the engine out I inspected and re - wrapped the harness near the egr but never saw any issues there or anywhere else.
 
60 toy ota said:
If it were the ecu ground you would most definitely have other running symptoms
Click to expand...
I agree, I think I'll hook my meter up to the communication wire and do a wiggle test to see if I ever lose continuity.
 
jonheld said:
This has been discussed several times in the past and was one of the very first things I did when I got my LX450 home.
The ECU harness runs along the bottom metal support for the lower dash behind the glovebox. This is a common chafe point.
I wrapped the harness and added a section of wire insulation along that lower support.
Good for the foreseeable future.
Click to expand...
Guess I got some finagling to do 🍌
 
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