MIL Circuit

3MZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: MIL Circuit

MIL Circuit

DESCRIPTION

The MIL (Malfunction Indicator Lamp) is used to indicate vehicle malfunctions detected by the ECM (included in the hybrid vehicle control ECU). When the power switch on (IG), power is supplied to the MIL circuit, and the ECM provides the circuit ground which illuminates the MIL.
The MIL operation can be checked visually. When the ignition switch is first turned on (IG), the MIL should be illuminated and should then turn off. If the MIL remains illuminated or is not illuminated, conduct the following troubleshooting procedure using the Techstream.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. CHECK THAT MIL IS ILLUMINATED
(a) Turn the ignition switch on (IG).
(b) Check the illumination of the MIL.
Result:

B -- CHECK THAT ENGINE STARTS
A -- Continue to next step.
2. CHECK WHETHER MIL TURNS OFF
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG) and turn the Techstream on.
(c) Select the following menu items: Powertrain / Engine and ECT / Trouble Code.
(d) Check if any DTCs have been stored. Note down any DTCs.
(e) Clear the DTCs DTC Check / Clear.
(f) Check if the MIL goes off.
Standard:
MIL goes off.
NG -- CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS)
OK -- REPAIR CIRCUITS INDICATED BY OUTPUT DTCS
3. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS)

(a) Disconnect the hybrid vehicle control ECU connector.
(b) Turn the power switch on (IG).
(c) Check that the MIL is not illuminated.
OK:
MIL is not illuminated.
(d) Reconnect the hybrid vehicle control ECU connector.
NG -- CHECK HARNESS AND CONNECTOR (COMBINATION METER - HYBRID VEHICLE CONTROL ECU)
OK -- REPLACE HYBRID VEHICLE CONTROL ECU
4. CHECK HARNESS AND CONNECTOR (COMBINATION METER - HYBRID VEHICLE CONTROL ECU)

(a) Disconnect the hybrid vehicle control ECU connector.
(b) Disconnect the combination meter connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for Open):

Standard resistance (Check for Short):

(d) Reconnect the hybrid vehicle control ECU connector.
(e) Reconnect the combination meter connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (COMBINATION METER - HYBRID VEHICLE CONTROL ECU)
OK -- REPLACE COMBINATION METER ASSEMBLY
5. CHECK THAT ENGINE STARTS
(a) Turn the power switch on (IG).
(b) Switch the hybrid vehicle control ECU from normal mode to check mode Check Mode Procedure.
(c) Start the engine.
Result:

HINT: *: The Techstream cannot communicate with the hybrid vehicle control ECU.

B -- GO TO VC OUTPUT CIRCUIT
A -- Continue to next step.
6. CHECK HARNESS AND CONNECTOR (COMBINATION METER - BODY GROUND)

(a) Disconnect the hybrid vehicle control ECU connector.
(b) Turn the power switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:

(d) Reconnect the hybrid vehicle control ECU connector.
NG -- CHECK HARNESS AND CONNECTOR (COMBINATION METER - HYBRID VEHICLE CONTROL ECU)
OK -- REPLACE HYBRID VEHICLE CONTROL ECU
7. CHECK HARNESS AND CONNECTOR (COMBINATION METER - HYBRID VEHICLE CONTROL ECU)

Standard resistance (Check for Short):