while looking for a parasite drain problem; .... got the DTC tool (07WAZ-001010A) & have got to this point, .... finding this single b1278 DTC code Headlight Switch ON Position malfunction (via the non-HDS process in Service Manual pages 22-96...)

- there are multiple subsequent tests to (maybe) isolate the specific cause, listed in the Honda Service Manual using the HDS (which i don't have)

can anyone whose had this b1278 code offer some easy "try first " solution(s)??

so while i clear the code & then plod along with some tedious tests i can actually do without HDS , ... a separate question arises:
Can aftermarket LED headlites possibly cause this?

one of the listed possible causes is : circuit poor electrical connection
( i note suggestion #3 here about unplugging the connectors - good idea! https://www.hondaaccordforum.com/for...ing-bad-58549/ )

( I only ask cuz i have a situation in Miata where the LED "bulbs" cause the high-beam indicator to not work; so it seems that LED's interrupt the "normal" signals in a way that our "computers" (BCAN & Multiplexers do not like )) - i know LED voltages or currents are a problem with turn-signals / trailer circuits which requires "adapters"

UPDATE - per manual - cleared the code, cycled the switch, rechecked - NO code = temporarily fixed

 

I don't remember seeing b1278 issues on this site. I'm not sure if your parasitic draw testing could cause a b1278. I'd wait to see if clearing the code fixes the problem then you can look at options for testing without a HDS.

Out of curiosity, did you have any issues with the headlight switch when you had the b1278 code?

 

NO - no obvious problems with headlite switch or combo switch - afik everything works like it should