Compression Ignition Addict
Join Date: Dec 2007
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Buzzing relays are a sign of low voltage, insufficient current available to hold the relay closed. This could be several things...
On an '02 I would first look at the connection under the hood where the B+ makes its transition to the Fuseable Links that feed the fusebox. Look under the Airbox, at the top of the inner wheel well, for a 1"X1" black plastic cover that says High Current (or something like that) for the corroded connection there that could be limiting the current to the block.
Next, this could be as simple as bad batteries or their cables & connections. Clean, scrape, grease, & tighten them all (both sides) and have the batteries Load Tested at a high rate (not the "dinky 100A testers the parts stores use on 4clys, our BIG batteries should be tested at 250-300A)