Inspection Procedure

WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

Check heater main relay.
PREPARATION: Remove heater main relay from engine room J/B.

Check: continuity between each pair of terminals of heater main relay. See Fig 2.

Fig 1: Identifying Heater Main Relay Terminals
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Fig 2: Heater Main Relay Terminal Specifications (No Voltage Applied)
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PREPARATION: Apply battery positive voltage between terminals 3 and 5.

Check: continuity between each pair of terminals. See Fig 3.

Fig 3: Heater Main Relay Terminal Specifications (Voltage Applied)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Replace hater main relay.
2. OK: Go to step 2 .
Check HTR fuse
PREPARATION: Remove HTR fuse from engine room J/B.

Check: continuity of HTR fuse. If OK , continuity exists.

Fig 4: Locating HTR Fuse
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Check for short in all the harness and components connected to the HTR fuse. See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION .
2. OK: Go to step 3 .
Check harness and connector between heater main relay and body ground, heater main relay and body ECU . See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION .
1. NG: Check and replace harness and connector.
2. If OK , check multiplex communication system. See HOW TO PROCEED WITH TROUBLESHOOTING MULTIPLEX COMMUNICATION SYSTEM .