Cranking Holding Function Circuit

1NZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: Cranking Holding Function Circuit

Cranking Holding Function Circuit

DESCRIPTION

The cranking holding control system provides a current to the starter when the ECM detects the ignition switch's start signal (STSW). When the ECM judges that the engine has started, the system cuts the current to the starter. When the ECM receives the STSW signal, it turns on the ACC (Accessory) relay, which prevents flickering of the combination meter, clock and audio system. 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 ST 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. READ VALUE USING TECHSTREAM (STARTER SIGNAL)
(a) Connect a Techstream to the DLC3.
(b) Turn the ignition switch to ON and turn the tester ON.
(c) Turn the tester ON.
(d) Select the following menu items: Powertrain / Engine and ECT / Engine and ECT / Data List / All Data / Starter Signal.
(e) Check the result when the ignition switch is turned to ON and START.
OK:






OK -- INSPECT BATTERY
NG -- Continue to next step.
2. INSPECT ECM (STSW VOLTAGE)




(a) Disconnect the A21 ECM connector.
(b) Measure the voltage between the terminals of the ECM connector and body ground while cranking the engine.
Standard voltage:






Result:





(c) Reconnect the ECM connector.
C -- INSPECT IGNITION SWITCH
B -- INSPECT ECM (STAR VOLTAGE)
A -- Continue to next step.
3. INSPECT ECM (STAR VOLTAGE)




(a) Disconnect the C27 Park/Neutral Position (PNP) switch connector.
(b) Measure the voltage between the terminals of the PNP switch connector and body ground while cranking the engine.
Standard voltage:





(c) Reconnect the PNP switch connector.
NG -- CHECK HARNESS AND CONNECTOR (IGNITION SWITCH - PARK/NEUTRAL POSITION SWITCH - ECM)
OK -- Continue to next step.
4. INSPECT PARK/NEUTRAL POSITION SWITCH




(a) Disconnect the C27 PNP switch connector.
(b) Check the resistance between each terminal shown below when the shift lever is moved to each range.
Standard resistance:





(c) Reconnect the PNP switch connector.
NG -- REPLACE PARK / NEUTRAL POSITION SWITCH
OK -- Continue to next step.
5. CHECK HARNESS AND CONNECTOR (PARK/NEUTRAL POSITION SWITCH - ECM)




(a) Disconnect the C27 PNP switch connector.
(b) Disconnect the A21 ECM connector.
(c) Check the resistance.
Standard resistance (Check for open):






Standard resistance (Check for short):





(d) Reconnect the PNP switch connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
6. INSPECT ECM (STAR VOLTAGE)




(a) Disconnect the A16 clutch start switch connector.
(b) Measure the voltage between the terminals of the clutch start switch connector and body ground while cranking the engine.
Standard voltage:





(c) Reconnect the clutch start switch connector.
NG -- CHECK HARNESS AND CONNECTOR (IGNITION SWITCH - CLUTCH START SWITCH - ECM)
OK -- Continue to next step.
7. INSPECT CLUTCH START SWITCH




(a) Disconnect the A16 clutch start switch connector.
(b) Check the resistance between the terminals of the clutch start switch.
Standard resistance:





(c) Reconnect the clutch start switch connector.
NG -- REPLACE CLUTCH START SWITCH
OK -- Continue to next step.
8. CHECK HARNESS AND CONNECTOR (CLUTCH START SWITCH - ECM)




(a) Disconnect the A16 clutch start switch connector.
(b) Disconnect the A21 ECM connector.
(c) Check the resistance.
Standard resistance (Check for open):






Standard resistance (Check for short):





(d) Reconnect the clutch start switch connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
9. INSPECT IGNITION SWITCH




(a) Disconnect the D8 ignition switch connector.
(b) Check the resistance between the terminals shown below.
Standard resistance:





(c) Reconnect the ignition switch connector.
NG -- REPLACE IGNITION SWITCH
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - IGNITION SWITCH - BATTERY)
10. CHECK HARNESS AND CONNECTOR (IGNITION SWITCH - PARK/NEUTRAL POSITION SWITCH - ECM)




(a) Disconnect the D8 ignition switch connector.
(b) Disconnect the C27 PNP switch connector.
(c) Disconnect the C20 ECM connector.
(d) Check the resistance.
Standard resistance (Check for open):






Standard resistance (Check for short):





(e) Reconnect the ignition switch connector.
(f) Reconnect the PNP switch connector.
(g) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
11. CHECK HARNESS AND CONNECTOR (IGNITION SWITCH - CLUTCH START SWITCH - ECM)




(a) Disconnect the D8 ignition switch connector.
(b) Disconnect the A16 clutch start switch connector.
(c) Disconnect the C20 ECM connector.
(d) Check the resistance.
Standard resistance (Check for open):






Standard resistance (Check for short):





(e) Reconnect the ignition switch connector.
(f) Reconnect the clutch start switch connector.
(g) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
12. INSPECT BATTERY
(a) Check that the battery is not depleted.
OK:
Battery is not depleted.
NG -- REPLACE BATTERY
OK -- Continue to next step.
13. CHECK BATTERY TERMINAL
(a) Check that the battery terminals are not loose or corroded.
OK:
Battery terminals are not loose or corroded.
NG -- REPAIR OR REPLACE BATTERY TERMINAL
OK -- Continue to next step.
14. CHECK HARNESS AND CONNECTOR (PNP SWITCH OR CLUTCH START SWITCH - ST RELAY)
(a) Remove the ST relay from the engine room relay block.




(b) Disconnect the C27 PNP switch connector (A/T).
(c) Disconnect the A16 clutch start switch connector (M/T).
(d) Check the resistance.
Standard resistance (Check for open):






Standard resistance (Check for short):





(e) Reinstall the ST relay.
(f) Reconnect the PNP switch connector (A/T).
(g) Reconnect the clutch start switch connector (M/T).
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- CHECK AND REPLACE STARTER RELAY AND STARTER