When you are troubleshooting CID 334, it is necessary to determine the setting of the spare output. Setpoint SP11 is used to program the spare output. See Systems Operation, "Spare Input/Output Programming OP6".
- SP11 = 1 through 8, for high/low logic.
- SP11 = 9, for serial data link.
If necessary, check the setpoint SP11 in order to determine the operation of the spare output. Perform the corresponding procedure that follows.
High/Low Logic Circuit
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| Illustration 1 | g00487533 |
System Schematic For Spare Output When used as a high/low logic circuit. | |
The spare output on the GSC is strictly used for the customer. The spare output is programmed to activate under a variety of conditions. The default is set for the output to activate when the engine is in the cooldown (SP11 = 7). The GSC treats this diagnostic code as a alarm fault. For more information, see Systems Operation, "Spare Input/Output Programming OP6". The responsibility of documenting any connections to this spare output falls on the customer and/or the dealer. Also, The responsibility of troubleshooting any connections to this spare output falls on the customer and/or the dealer.
The voltage on the spare output is approximately 3.0 DCV when the spare output is not active. The voltage is approximately 3.0 DCV when there are no connections to the spare output. When the spare output is active, the voltage on the spare output is approximately 0 volts. The spare output is capable of drawing (sinking) approximately 100 mA.
Procedure
The following condition could be a possible cause of a CID 334 FMI 3.
- A short to the battery ("B+") of the signal for the spare output is present.
Troubleshooting of a spare output fault is direct. The FMI defines the diagnostic code. FMI 3 is a short to the +battery. In order to find the exact cause of the diagnostic code, use the following information: the FMI, the system schematic for the spare output and the documentation that is provided by the dealer and/or the customer
Serial Data Link
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| Illustration 2 | g00487536 |
System Schematic For Spare Output When used as a serial data link. | |
The GSC communicates with the relay driver module (RDM) by a serial data link. The serial data link is enabled when the setpoint SP11 is 9. For more information, see Systems Operation, "Spare Input/Output Programming OP6".
When the data link malfunctions, R1 output (terminal 2 of the RDM) will be activated on and off at a rate of 0.5 Hz. Relays "R2" through "R9" will maintain the current states or the relays will default to off. This is controlled by a jumper between terminals 6 and 7 of the RDM. If a jumper is NOT present when the serial data link has a fault, the relay outputs ("R2" through "R9") will maintain the current states. If the jumper is present, "R2" through "R9" will default to OFF.
Note: The maximum distance between a module and the GSC is 305 m (1000 ft). If this specification is not met, it is possible for the data link to malfunction. Also, a diagnostic code of CID 334 could occur. If the distance is not in compliance with the specification, shorten the distance between the RDM and the GSC.
Note: Faults are created when the harness connector (40 contact) is disconnected from the GSC during these troubleshooting procedures. Clear these created diagnostic codes after the particular diagnostic code is corrected. In a properly operating system, when the harness connector is removed from the GSC, the following diagnostic codes are recorded:
- CID 100 FMI 2 pressure sensor (engine oil)
- CID 110 FMI 2 temperature sensor (engine coolant)
- CID 111 FMI 3 fluid level sensor (engine coolant)
- CID 190 FMI 3 speed sensor (engine)
- CID 336 FMI 2 switch (engine control)
- CID 590 FMI 9 engine ECM
Procedure
The following condition could be a possible cause of a CID 334 FMI 3.
- A short to the + battery of the signal for the data is present.
The GSC is not able to detect an open circuit condition of the data link for the relay driver module. Clear the diagnostic code from the fault log after troubleshooting is complete.
- Check the voltage of the signal for the data.
- At the RDM, measure the DC voltage from terminal 4 (positive meter lead) to terminal 7 (negative meter lead).
Expected Result: The voltage should change constantly. The voltage should change within the range of 0 to 10 DCV.
Results:
- OK - The voltage measurement is correct. Proceed to 3.
- NOT OK - The voltage measurement is NOT correct. Proceed to 2.
- OK - The voltage measurement is correct. Proceed to 3.
- At the RDM, measure the DC voltage from terminal 4 (positive meter lead) to terminal 7 (negative meter lead).
- Check the voltage of RDM and the GSC.
- At the RDM, disconnect all wires from terminal 4.
- Disconnect the harness connector from the GSC.
- At the RDM, measure the DC voltage from terminal 4 (positive meter lead) to terminal 7 (negative meter lead). Voltage should be 11.6 ± 0.5 DCV.
- Measure the voltage from the contact 36 of the GSC to the ground ("B-") terminal of the relay module. The voltage should change constantly. The voltage should change within the range of 0 to 5.5 DCV.
Expected Result: For 2.c, the voltage should be 11.6 ± 0.5 DCV. For 2.d, the voltage should change constantly. The voltage should change within the range of 0 to 5.5 DCV.
Results:
- OK - Both voltage measurements are correct. Proceed to 3.
- NOT OK - Voltage measured at the RDM is NOT correct. Replace the RDM. STOP.
- NOT OK - Voltage measured at the GSC is NOT correct. Replace the GSC. STOP.
- OK - Both voltage measurements are correct. Proceed to 3.
- Check for the short in the harness.
- Disconnect the harness connector from the GSC.
- At the RDM, remove wire 1-PK from terminal 4.
- Measure the resistance from the wire at RDM terminal 4 to the positive battery ("B+") terminal of the relay module on the rear of the GSC.
- Measure the resistance from the wire at RDM terminal 4 to ground ("B-") terminal of the relay module on the rear of the GSC.
Expected Result: Both measurements should be greater than 20000 ohms.
Results:
- OK - Both resistance measurements are correct. Check the electrical connectors, terminals and wiring. See Testing And Adjusting, "Electrical Connector - Inspect". If the diagnostic code still exists after the inspection, replace the RDM. STOP.
- NOT OK - Either one or both of the resistance measurements are NOT correct. The harness wiring with the incorrect resistance measurement is shorted. Troubleshoot and repair the faulty harness wiring between the RDM and the GSC. See the preceding System Schematic. STOP.
- OK - Both resistance measurements are correct. Check the electrical connectors, terminals and wiring. See Testing And Adjusting, "Electrical Connector - Inspect". If the diagnostic code still exists after the inspection, replace the RDM. STOP.