Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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H43 - Check HO2S Heater Relay Circuit For Short to Power

- Key "OFF".

- Heated Oxygen Sensor (HO2S) relay disconnected.

- Breakout box installed, leave Powertrain Control Module (PCM) disconnected.

- Measure the resistance between test pin 14 and test pins 37/57 at the breakout box.

- Is the resistance greater than 10,000 ohms?

Yes -- Go to H44

No -- Service short in harness. Remove breakout box. Reconnect all components. Rerun Quick Test.