Unlike the earlier models where you would just replace the main relay and it would be peachy, new updated harness with mulitiple relays!!!! Im experiencing a voltage drop when the car is loaded with the blower on full the HID on Anything that would require a decent amount of voltage, including the electric steering. The ignition dies dash goes haywire, radio shuts down, looses all main and secondary power like a kill of the ignition switch...also another fault with the S2's. The alt is charging (tested and tried) new interstate battery, terminals good, i went through and even added additional grounds from the negative terminal to chassis ground and to the block, Cleaned oem connections, Ive tested and tried all relays went through every test with my modis and snap on relay tester, traced every wire through the fire wall into all main terminal pins, gotten a little crazy with wiring diagrams so much im seeing it in my sleep. fuse boxes fuses, rough roads, smooth highway, went as far as a ECM...pulling my hair out! any help without scarcasm would be greatly apprecieated

 

You'll probably have more luck at theses places:

Honda S2000 - Honda-Tech

S2000 Forums : S2KI

 

all grounds clean and good?

 

Just an idea...but working at the dealer. i've saw this symptom on a few other models.....To me it seems like you're having an intermittent igntion switch(the electrical harness that goes to the interior fuse box) problems.......just my 2 cents