ABS...VSA...BRAKE Warning lights comes ON and OFF
 

I have 2009 Honda Accord Sedan V4. When i drive the car and pass any uneven surface than ABS indicator, the VSA indicator and the brake system indicator come on. Moreover, when I park the car for more than 8 hours at night than lights goes away until i cross any uneven surface.
I used Lunch tech X431 code reader and it gives the code 121-01, VSA modulator solenoid valve malfunction. But I hope that modulator does not have any problem, as the lights did not stay permanently. Some times I drove the car for 35 KM but the indicators stay off
Guys please help me ....

Attached is diagnostic. Check car-part.com and ebay for replacement modulator control unit as indicated.

good luck

Dear TexasHonda, Thanks for the help. As i mentioned that ABS, VSA and brake lights did not stay permanently. Do not you think that ABS modulator is not necessarily in bad shape and there could be other causes as well?
Again today morning, when I started my car, lights went away and they came after I drove 10 KM.
Any Idea?

First I'd check the connections (step 7 on the 2nd page of what Tex posted).

Seems like bad valves would LIKELY(?) be bad all the time, but flaky wiring might come & go. Unplug it & check for corroded pins, loose socket, stuff like that. I've even seen threads where the final answer was that an individual wire/socket had come un-clipped and pushed partway out from the plastic body of the plug.

It might turn out to be a bad modulator; but you may as well rule out the stuff that you can fix yourself, like flaky plugs, maybe wiring that has been chewed by rodents, or other things like that.

I know earlier ABS controls reset on each shutdown/startup so a delay means the system is repeatedly checking (a leak likely) and finding a problem. After several repeats code is set.

On earlier models (94-97) you could hear/feet the modulator pump buzz when pump re-engaged to charge accumulator.

If a modulator is needed, used parts are way to go.

good luck