Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Normally this is caused by a bad ignition switch. There are multiple sets of contacts within the ignition switch. The ABS power feed circuit and heater fan circuit share one of these sets of contacts. When the contacts fail, the high amperage draw of the heater fan will drop voltage to the abs system, causing the warning lights to come on. Replacing the ignition switch should fix your problem.