I have a noise in my dash that sounds like cereal being poured on a snare drum-a little like a vibrating styrofoam cooler in the back of the station wagon. It is sounds like a small switch or solenoid is shorted, or switching rapidly. This is all I have been able to figure out so far since it has only been going on for two days: (1997 T100 4x4-5sp)

1. The sound seems to come from in the dash area between the instrument cluster and steering column.
2. It is rather intermittent-crackling for 5-20 seconds, then no noise for 20-60 seconds.
3. It only happens when the vehicle is moving, mostly at 30+mph. I have never heard the noise when the truck was stopped, but I have heard it briefly as I pulled away from a stop.
4. It seems slightly releated to the vibration of the truck from the engine or road, but not really sure.
5. All accessories, fan, ac, lights seem to work normally during the noise.
6. I know it is electrical because when I turn the engine and power off at highway speed, the noise stops. With the power on, but engine off, at 40mph, the noise returns. (I tried this test several times to be sure.)

It doesn't seem to affect anything, but I don't like hearing electrical noises between my legs.

Any ideas? <img src="/forums/images/graemlins/confused.gif" alt="" />

I got home from work and checked a couple of things and found a loose wire from the ADD light plug touching part of the crossmember. The wind and vibrations from driving would cause the wire to touch and short out, making the ADD relay click and snap. The ADD relay seems to be in the location I described, and I hope I didn't damage it. If I did, I'll dump the ADD.

Eh, dump it anyways... <img src="/forums/images/graemlins/smile.gif" alt="" />