Cranking Holding Function Circuit

3UR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: Cranking Holding Function Circuit
- Cranking Holding Function Circuit

DESCRIPTION

The cranking holding control system provides current to the starter when the ECM detects the ignition switch's start signal (STSW). When the ECM performs a firing judgment, the system cuts current to the starter. When an ECM receives the STSW signal, it turns on the ACC Cut relay, which prevents flickering of the combination meter, clock, audio system, etc. Also, the ECM sends a signal to the ECM's STAR terminal. Then the STAR output signal travels through the Park / Neutral Position (PNP) switch to the STARTER relay, causing the starter to activate.

When the engine is cranking, the starter operation signal is sent to the ECM's STA terminal.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK CRANKING

(a) Check the cranking of the engine.

Result





C -- CHECK HARNESS AND CONNECTOR (IGNITION SWITCH - ECM)

B -- READ VALUE USING TECHSTREAM (STARTER SIGNAL)

A -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

2. READ VALUE USING TECHSTREAM (STARTER SIGNAL)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream ON.

(d) Enter the following menus: Powertrain / Engine and ECT / Data List / Starter Signal.

(e) Read values.

(f) Check the result when the ignition switch is turned to ON and when the engine is started.

Standard:





NG -- CHECK IGNITION SWITCH (POWER SOURCE)
OK -- Continue to next step.

3. INSPECT STARTER RELAY (ST)

(a) Remove the starter relay (ST) from the engine room relay block Testing and Inspection.





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

Standard resistance:





NG -- REPLACE STARTER RELAY (ST) Testing and Inspection
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (ST RELAY - PNP SWITCH)





(a) Remove the ST relay from the engine room relay block Testing and Inspection.

(b) Disconnect the D35 PNP switch.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

5. CHECK STARTER RELAY (POWER SOURCE)





(a) Remove the ST relay from the engine room relay block Testing and Inspection.

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

Standard voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STARTER RELAY (ST) - BATTERY, BODY GROUND)
OK -- Continue to next step.

6. INSPECT STARTER

(a) Inspect the starter Testing and Inspection.

NG -- REPAIR OR REPLACE STARTER Removal

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STARTER - STARTER RELAY (ST), BATTERY)

7. CHECK IGNITION SWITCH (POWER SOURCE)





(a) Disconnect the J9 ignition switch connector.

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

Standard voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (IGNITION SWITCH - BATTERY POSITIVE TERMINAL)
OK -- Continue to next step.

8. INSPECT IGNITION SWITCH

(a) Inspect the ignition switch Testing and Inspection.

NG -- REPLACE IGNITION SWITCH Removal
OK -- Continue to next step.

9. INSPECT PARK / NEUTRAL POSITION SWITCH (POWER SOURCE)





(a) Disconnect the D35 PNP switch connector.

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

Standard voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (PNP SWITCH - IGNITION SWITCH)
OK -- Continue to next step.

10. INSPECT PARK / NEUTRAL POSITION SWITCH





(a) Disconnect the D35 PNP switch connector.

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

Standard resistance:





Result





C -- REPLACE PARK / NEUTRAL POSITION SWITCH ASSEMBLY Removal

B -- REPLACE PARK / NEUTRAL POSITION SWITCH ASSEMBLY

A -- REPAIR OR REPLACE HARNESS OR CONNECTOR (PNP SWITCH - ECM)

11. CHECK HARNESS AND CONNECTOR (IGNITION SWITCH - ECM)





(a) Disconnect the J9 ignition switch connector.

(b) Disconnect the A24 ECM connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

12. CHECK HARNESS AND CONNECTOR (PNP SWITCH - ECM)





(a) Disconnect the D35 PNP switch connector.

(b) Disconnect the D74 ECM connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Removal