Monitor Description
WARNING: This page is about a different car, the 2018 Toyota Sequoia, 2017 Toyota Sequoia, and 2016 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.
These DTCs are designed to detect a malfunction in the air pump heater relay circuit. When the system is normal, the battery voltage is applied to terminal HAI1 of the ECM while the air pump heater relay (AI-HTR) is turned off, and the battery voltage is not applied to terminal HAI1 of the ECM while the air pump heater relay (AI-HTR) is turned on. The ECM illuminates the MIL and stores a DTC when either one of the following conditions is detected.
- The battery voltage is not applied to terminal HAI1 while the air pump heater relay (AI-HTR) is off.
- The battery voltage is applied to terminal HAI1 while the air pump heater relay (AI-HTR) is on.