Bob,
Sorry for the delay, I've been camping in the cold and wet along the banks of the Ohio river... motorcycle trip... brrrrr.
Anyway, the only thing that the engine harness and the forward lamp harness have in common is that they sit next to each other in the firewall connector plug. The only connection that forward lamp harness has to the engine is the temp sender as we discussed and the connections to the alternator (one fat red, one two wire plug).
Hope this helps.