Tech Tip Delco Denies Warranty Claims Delco Bulletin AT1002 has stated that the company will deny warranty claims on its heavy duty alternators due to blown diode trios. The bulletin says inadequate wiring protection causes shorts and ground conditions that damage alternators and discharges batteries. Delco Remy, Inc. will deny warranty for returns that have damaged diode trios not related to an internal defect. On vehicles equipped with circuits on the alternator’s “IT” terminal, a ground causes the current in the diode trio to exceed its 1 amp max rating and over- loads the internal circuit. This damage will normally activate the charge indica- tor lamp. The cause has been determined to be wiring without protective conduit (even on taped harnesses) which is prone to chafing and abrasion when routed along the edges of the truck frame and/or block. Electrical tape is not an effective shield against such damage. The company recommends covering all alternator wiring with corrugated, slit-loom covers, for example, “heat- stabilized nylon tubing, such as Panduit brand, CLT25N-C630.” Units affected include 20SI, 21S], 22S], 23S], 30SI, 33SL, 34S1, and 35S. For complete information, including photos, go to www.remyinc.com. Click on “Heavy Duty Electrical Systems,’ then “Technical/Fleet;’ and under “Application Engineering Bulletins” click on “Returns with Diode Trio Damage.”