Toyota Tundra Service Manual: Open in Secondary Air Injection System Heater Control Circuit (P144C,P144D)

DESCRIPTION

The ECM operates the air pump heater (AI HTR) relay which causes the air pump heater (AI HTR) to operate.

MONITOR DESCRIPTION

These DTCs are designed to detect a malfunction in the air pump heater (AI HTR) relay circuit. When the system is normal, the battery voltage is applied to terminal HAI1 of the ECM while the air pump heater (AI HTR) relay is turned off, and the battery voltage is not applied to terminal HAI1 of the ECM while the air pump heater (AI HTR) relay 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 (AI HTR) relay is off.
• The battery voltage is applied to terminal HAI1 while the air pump heater (AI HTR) relay is on.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

CONFIRMATION DRIVING PATTERN

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation).
4. Turn the ignition switch off and wait for at least 30 seconds.
5. Turn the ignition switch to ON and turn the Techstream on.
6. Wait for 10 seconds.
7. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the Air Pump Heater.
8. Activate the air pump heater for 10 seconds or more.

   HINT:

   • The active test activates the air pump heater for up to 60 seconds.
   • To protect the air pump heater, do not perform this test more than 4 times in a row.
9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
10. Read Pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
11. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
12. Input the DTC: P144C or P144D.
13. Check the DTC judgment result.

    Techstream Display	Description
    NORMAL	DTC judgment completed System normal
    ABNORMAL	DTC judgment completed System abnormal
    INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
    N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    HINT:

    • If the judgment result shows NORMAL, the system is normal.
    • If the judgment result shows ABNORMAL, the system has a malfunction.
14. If the judgment result is INCOMPLETE or N/A and no pending DTC is output, perform a universal trip and check for permanent DTCs (See page ).

    HINT:

    • If no permanent DTC is output, the system is normal.
    • If a permanent DTC is output, the system is malfunctioning.

WIRING DIAGRAM

Refer to DTC P0412 (See page ).

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

HINT:

Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

(a) Remove the air pump heater (AI HTR) relay from the engine room relay block.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

NG

REPLACE AIR PUMP HEATER (AI HTR) RELAY

OK

(a) Remove the air pump heater (AI HTR) relay from the engine room relay block.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

(a) Remove the air pump heater (AI HTR) relay from the engine room relay block.

(b) Disconnect the D74 ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR