Woodward GECO, Technical Manual, Page: 79 / 90

Manual 03554 GECO

Stoichiometric
Woodward 71
Troubleshooting
The diagnostic functions of the GECO
 Stoichiometric system are reported to the
user either through the hand-held interface or the PC interface software. Certain
faults can also cause alarm or shutdown conditions, if these systems have been
configured and integrated into the existing engine control panel. The table below
describes all the faults and conditions which will cause an alarm or shutdown
condition. In addition, the plotting and datalogging features of the PC interface
software (see Chapter 3, Operation) can be very valuable for troubleshooting an
intermittent fault or difficult diagnosis.
Diagnostic Faults–Indication only Fault Conditions
No Alarm or Shutdown
Closed loop valve limit low Valve Command <= 5.0%
Closed loop valve limit high Valve Command >= 99.0%
Adaptive limit low Adaptive <= -5.0%
Adaptive limit high Adaptive >= 7.0%
DC Power supply voltage low Voltage < 9.5 V and RunMode = RUNNING
DC Power supply voltage high Voltage > 31.0 V and RunMode = RUNNING
ECU Processor Internal microprocessor errors
Trigger Noisy G-lead speed signal
CJC Sensor open > 4.95 V (> 300 °F)
CJC Sensor lower than expected < 0.05 V (< 45 °F)
Alarm and Shutdown Configuration Fault Conditions
Disable/Enable/Shutdown
UEGO max voltage > 1.1 V
EGO health <35%
TC open > 40 mV
TC lower than expected <30 deg. F above CJC sensor after 240 sec
run time
MAP low < 0.25 Vdc
MAP high > MAP high pressure
Valve1 current min <0.1 A and Valve Cmd > 30%
Valve1 current max > 0.6 A and Valve Cmd < 50%
Valve2 current min < 0.1 A and Valve Cmd > 30%
Valve2 current max > 0.6 A and Valve Cmd < 50%
Shutdown Only Fault Conditions
TCupstream temperature limit PC configurable
TCdnstream temperature limit PC configurable
Suggested Troubleshooting Procedures
When a diagnostic fault is indicated, the following guidelines will help to quickly
find and solve the cause. The steps should be taken in order; the possible
causes are listed in order from most likely to less likely. The following section
also lists trouble symptoms that may not set an indicated fault. Please contact
the nearest Woodward distributor or service facility for further technical support.
Possible Fault Causes
Valve Limit Low:
Carburetor too rich
Upstream EGO – check EGO health
High fuel supply pressure
Fuel metering valve
Valve Limit High:
Carburetor too lean
Upstream EGO - check EGO health
Low fuel supply pressure
Fuel metering valve