Radiator Fan Operates Continuously With Key On

Ensure engine coolant is less than 194°F (90°C). Remove fan No. 1 relay from fuse and relay box. Turn ignition on. If fan motor does not run, go to next step. If fan motor runs, check for a short to voltage in Black/Red wire between fuse and relay box, radiator fan motor and A/C fan No. 2 relay. If Black/Red wire is okay, replace fuse and relay box.
Check fan No. 1 relay connector terminal No. 1, with a test light connected to battery voltage. If test light does not glow, go to next step. If test light glows, replace fan No. 1 relay and check system operation. If fan motor continues to run, replace fuse and relay box.
NOTE: Models not equipped with A/C have a shorting clip in place of A/C triple pressure switch.
Backprobe A/C triple pressure switch connector terminal No. 2 (Light Green wire) with a test light connected to battery voltage. If test light glows, go to next step. If test light does not glow, check for open in Light Green wire between A/C triple pressure switch connector and fan thermoswitch. If Light green wire is okay, replace fan thermoswitch.
Check for open in Light Green/Black wire between fuse and relay box and A/C triple pressure switch connector. If Light Green/Black wire is okay, replace A/C triple pressure switch (A/C equipped models) or shorting clip (non-A/C models).

Fig 1: Identifying Fuse & Relay Box Connectors & Terminals (Top)
Courtesy of GENERAL MOTORS CORP.

Fig 2: Identifying Fuse & Relay Box Connectors & Terminals (Bottom)
Courtesy of GENERAL MOTORS CORP.