Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSTOYOTA2004TUNDRA 4WD V8-4.7L (2UZ-FE)REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTTRANSMISSION CONTROL SYSTEMSTESTING AND INSPECTIONSCAN TOOL TESTING AND PROCEDURESDTC CHECK (CHECK MODE)
2004 Toyota Tundra 4WD V8-4.7L (2UZ-FE)
DTC Check (Check Mode)
2004 Toyota Tundra 4WD V8-4.7L (2UZ-FE)SECTION DTC Check (Check Mode)
Inspect Diagnosis (Check Mode)
HINT:
Hand-held tester only:
Check mode has a higher sensitivity to malfunctions and can detect malfunctions that normal mode cannot detect. Check mode can also detect all the malfunctions that normal mode can detect.
a. Check the DTC.
1. Check the initial conditions.
- Battery positive voltage 11 V or more
- Throttle valve fully closed
- Transmission in the P position
- Air conditioning switched OFF
2. Turn the ignition switch OFF.

3. Connect the hand-held tester to the DLC3.
4. Turn the ignition switch ON and push the hand-held tester main switch ON.

5. Prepare the hand-held tester.
6. Change the ECM to check mode with the handheld tester. Make sure the MIL flashes as shown in the illustration.
NOTE:
All DTCs and freeze frame data recorded will be erased if:
1. the hand-held tester is used to change the ECM from normal mode to check mode or vise-versa; or
2. during check mode, the ignition switch is turned from ON to ACC or OFF.
7. Start the engine. The MIL should turn off after the engine starts.
8. Ciliate the conditions of the malfunction described by the customer.
9. After simulating the malfunction conditions, use the hand-held tester diagnosis selector to check the DTCs, freeze frame data, and other data.
10. After checking the DTC, inspect the applicable circuit.
b. Clear the DTC.
Operate the OBD II scan tool or the hand-held tester to erase the DTC and freeze frame data (see the instruction manual for the OBD II scan tool or the hand-held tester).
HINT:
Hand-held tester only:
Check mode has a higher sensitivity to malfunctions and can detect malfunctions that normal mode cannot detect. Check mode can also detect all the malfunctions that normal mode can detect.
a. Check the DTC.
1. Check the initial conditions.
- Battery positive voltage 11 V or more
- Throttle valve fully closed
- Transmission in the P position
- Air conditioning switched OFF
2. Turn the ignition switch OFF.
3. Connect the hand-held tester to the DLC3.
4. Turn the ignition switch ON and push the hand-held tester main switch ON.
5. Prepare the hand-held tester.
6. Change the ECM to check mode with the handheld tester. Make sure the MIL flashes as shown in the illustration.
NOTE:
All DTCs and freeze frame data recorded will be erased if:
1. the hand-held tester is used to change the ECM from normal mode to check mode or vise-versa; or
2. during check mode, the ignition switch is turned from ON to ACC or OFF.
7. Start the engine. The MIL should turn off after the engine starts.
8. Ciliate the conditions of the malfunction described by the customer.
9. After simulating the malfunction conditions, use the hand-held tester diagnosis selector to check the DTCs, freeze frame data, and other data.
10. After checking the DTC, inspect the applicable circuit.
b. Clear the DTC.
Operate the OBD II scan tool or the hand-held tester to erase the DTC and freeze frame data (see the instruction manual for the OBD II scan tool or the hand-held tester).
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.