Code 46 - THERMACTOR Air By-Pass
- Remove vacuum hose at TAB valve and connect gauge to hose. Start engine and raise speed above 2500 RPM to start "Functional Test". Observe gauge during initial pulses. If pulses are above and below 5 in. Hg, MCU is okay, check Thermactor pump. If pulses are always above 5 in. Hg, check Thermactor pump. If pulses are always below 5 in. Hg, go to next step.
- Check vacuum hoses between vacuum source, TAD solenoid, and TAB valve for leaks or blockage. Repair if necessary. If hoses are okay, go to next step.
- Check at TAB solenoid output to be sure vacuum is present when solenoid is deactivated. If no vacuum is present, replace solenoid. If vacuum is present, go to next step.
- Disconnect MCU and TAB solenoid connectors. Measure resistance between ground and MCU pin 9. If resistance is less than 1000 ohms, repair short to ground. If resistance is greater than 1000 ohms, replace MCU module.
- Check TAB solenoid output to make sure vacuum is not present when solenoid is deactivated. If vacuum is present, replace solenoid. If vacuum is not present, go to next step.
- Disconnect MCU and TAB solenoid connectors. Measure resistance between ground and MCU pin 11. If resistance is less than 1000 ohms, repair short to ground. If greater than 1000 ohms, replace MCU module.