DTC 1-4-5
1-4-5 INJECTOR 4Preconditions for DTCs
^ If an injector circuit is short circuited to ground/voltage or if there is a break in the circuit, the ECM interprets this as a fault and sets the DTC for the relevant injector.
Substitute values
^ Idle air trim inhibited.
^ Fuel trim inhibited.
Fault sources
^ Signal too high:
- Signal lead short circuited to voltage.
- Defective injector.
^ Signal too low:
- Signal lead short circuited to ground.
- Break in signal or voltage lead.
- Contact resistance in connections.
- Defective injector.
Fault symptom
^ The engine does not fire on all cylinders. Sometimes, the engine does not start up.
TESTING PROCEDURE
Status Message
^ Check current status message.
If Status message is: Permanent fault, signal too high:
- Proceed to: PERMANENT FAULT, SIGNAL TOO HIGH section below.
If Status message is: Permanent fault, signal too low:
- Proceed to: PERMANENT FAULT, SIGNAL TOO LOW section below.
If Status message is: Intermittent fault, signal too high:
- Proceed to: INTERMITTENT FAULT, SIGNAL TOO HIGH section below.
If Status message is: Intermittent fault, signal too low:
- Proceed to: INTERMITTENT FAULT, SIGNAL TOO LOW section below.
PERMANENT FAULT, SIGNAL TOO HIGH
Check the Injector
^ Switch Ignition OFF.
^ Disconnect the injector.
^ Connect an ohmmeter between the injector's connectors 1 and 2.
The ohmmeter should show approx. 14.5 Ohms at +20°C (68°F)
If reading is OK:
- Check the lead between the injector, connector 2 and ECM A23 for signs of short circuiting to voltage supply.
If the reading is incorrect:
- Try with a new injector.
PERMANENT FAULT, SIGNAL TOO LOW
Check Voltage Lead
^ Switch Ignition OFF.
^ Disconnect the injector.
^ Switch Ignition ON.
^ Connect a voltmeter between the injector's connector 1 and ground.
The voltmeter should show battery voltage.
If the reading is OK:
- Check the signal lead's resistance to ground.
If the reading is incorrect:
- Check the lead between the injector's connector 1 and the main relay (2/32) connector 3 for signs of a break.
Checking The Signal Lead's Resistance To Ground
^ Switch Ignition OFF.
^ Wait for about 150 seconds.
^ Injector disconnected.
^ Connect an ohmmeter between the injector's connector 2 and ground.
The ohmmeter should show 25 - 40K ohms.
If reading is OK:
- Proceed to: Checking the Injector section below.
If the ohmmeter shows infinite resistance:
- Proceed to: Checking the ECM's Connector section below.
If the ohmmeter shows approx. 0 ohms:
- Check the lead between the injector connection 2 and the ECM A23 for signs of short circuit to ground.
Checking The Injector
^ Switch Ignition OFF.
^ Injector disconnected.
^ Connect an ohmmeter between injector connectors 1 and 2.
The ohmmeter should show approx. 14.5 ohms at 20°C (68°F).
If reading is OK:
- The source of the DTC is poor contact between the injector's and/or ECM's connector. Remedy the connectors to eliminate the loose connection.
If reading incorrect:
- Test with a new injector.
Checking The ECM's Connector
^ Switch Ignition OFF.
^ Injector disconnected.
^ Remedy the ECM's connector with regard to contact resistance and oxidation.
^ ECM connected.
^ Connect an ohmmeter between injector connector 2 and ground.
The ohmmeter should show 25 - 40K ohms.
If reading is OK:
- The source of the DTC is poor contact in the ECM's connector.
If reading is incorrect:
- Check the lead between injector connector 2 and ECM A23 for signs of a break.
INTERMITTENT FAULT, SIGNAL TOO HIGH
Check Leads And Connections
^ Check the lead between the injector's connector 2 and ECM A23 for signs of an intermittent short circuit to voltage supply.
INTERMITTENT FAULT, SIGNAL TOO LOW
Check Leads And Connections
^ Check the injector's and/or ECM's connector for play and contact resistance and oxidation.
^ Check the lead between the injector's connector 1 and the main relay (2/32) connector 3 for signs of an intermittent break.
^ Check the lead between the injector connector 2 and ECM A23 for signs of an intermittent break or intermittent short circuit to ground.