K in think i have an idea.Lets get the d4 light fixed first.

Block the front tires set the e brake start it up put into D4.

At connector c437 i need to see if you have 12v to grn pin17 and yel pin18.
(back probe it with a volt meter).

It will help me build a plan.I think i see a problem between the accord and the lude.We should be able to fix it.