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LIFT TRUCK SERIES
G15S-2 G18S-2 G20SC-2 Plus
GC15S-2 GC18S-2 GC20SC-2 Plus
GC20E-3 GC25E-3 GC30E-3 GC32E-3 Plus
G20E-3 G25E-3 G30E-3 G32E-3 Plus
GC20P-3 GC25P-3 GC30P-3 GC32P-3 Plus
G20P-3 G25P-3 G30P-3 G32P-3 G33P-3 Plus
G35S-2 G40S-2 G45S-2 G50SC-2 Plus
G50S-2 G60S-2 G70S-2 Plus
May 7, 2004
CODE 7500
LT7500-E4
SUBJECT: TIER II FUEL SYSTEM FAULT CODES AND MANUALS
Daewoo recently published Service Bulletin LT7500-D4 to announce the availability of
theTier II Engine Analyzer Tool Kit. Daewoo strongly recommends that each dealership
and branch have one or more kits. Fortunately, the fuel systems also have built-in fault
code diagnostics that do not require the service tool. This diagnostic system is designed
for very simple troubleshooting when a service tool and computer are not available.
Daewoo considers this a user-friendly advantage over much of the competition with the
new Tier II fuel systems.
Applicable Daewoo serial number prefixes: FQ, FR, FY, G2, G3, G4, G5, G6, G9, GA,
GB, GH, GQ. These trucks say “Plus” on the side near the model number.
Diagnostics
The Check Engine light, found on the steering column dashboard under the steering
wheel, is used to display the flashing diagnostic fault codes. This is also called the
Malfunction Indicator Lamp (MIL). See Figure 1 on the next page. When the ignition key
is turned to the “ignition” position the light comes on. The light goes out after the engine
starts unless an active fault has been detected. When that happens the light remains on
until the fault is cleared. The fault codes are stored in the memory of the Small Engine
Control Module (SECM).
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Displaying the fault codes:
To display the fault codes:
1. Turn the ignition key on without cranking the engine.
2. Depress the accelerator pedal to the floor three times within five seconds.
Clearing the fault codes:
To clear the fault codes:
1. Turn the ignition key on without cranking the engine.
2. Depress the accelerator pedal to the floor ten times within five seconds.
Note: Do not clear the codes until the faults have been diagnosed and corrected.
Check Engine light
Figure 1: MIL or “check engine” light location on dash.
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Reading the fault codes:
All fault codes are two-digit codes. When the codes are retrieved and displayed per the
method above, the light flashes the appropriate number of times for each digit with a
short pause between digits, and a long pause between fault codes. For example, “fault
code 12” is displayed as one flash, then a .5 second delay, then two flashes. Then the
code flashes again (or the next code) after a 1.2-second delay.
Code 12 is displayed at the beginning of every code list. For example, if two fault
conditions exist and the SECM displays codes 52 and 74, the code list flashes 12, 52,
74, 12, 52, 74, 12, 52, 74, etc., using code 12 to indicate the beginning of the code list.
Note: If no fault exists, code 12 flashes continuously.
Interpreting the fault codes:
Some of the faults shut down the engine immediately, some cause a delayed shutdown.
Some trigger a “limp home” mode. For others the SECM simply indicates a fault and
takes no further action.
The following page is a list of all the fault codes with a brief description—a fault-code
“cheat sheet” for LP engines. It is imperative that every Daewoo technician keeps a
copy of this on hand as the new low-emissions trucks are placed in service. Daewoo
suggests that technicians practice displaying fault codes on new trucks; code 12 can be
displayed when no fault condition exists.
Manuals:
Woodward Industrial Controls has published a manual for each of the three types of
engines equipped with their fuel system on Daewoo trucks. They contain detailed
descriptions of the fault codes along with detailed troubleshooting procedures. The
manuals can be found on our web site in PDF format, titled “Fuel System Supplement”
in the Service Literature section. Please download these files to your computer as
needed. As new versions of engine service manuals from Daewoo become available,
they will also be posted to the web site, and be made available through our Parts
Department. Please check the web site periodically for updates for your particular model
and serial number.
Support:
The combination of the cheat sheet on the next page and the manuals from the Daewoo
web site should allow technicians to get a good jump on troubleshooting should a fault
condition develop. Please use the available tools before contacting Daewoo product
support.
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DAEWOO TIER II ENGINE/FUEL SYSTEM FAULT CODES
FAULT
CODE
NAME
FAULT DESCRIPTION
12
NONE
Signifies the end of one pass through the fault list
14
ECTSensorInputLow
Normally set if the coolant sensor wire is shorted to ground
15
ECTSensorInputHigh
Set if the coolant sensor wire is disconnected or open
16
ECTRangeHigh
Coolant sensor has measured an excessive temperature or
shorted to GND
22
ThrottleSensorInputLo
TPS1 signal wire is open
23
ThrottleSensorInputHi
TPS1 signal wire is shorted
24
ThrottleSensorRangeLo
TPS Sensor malfunction
25
ThrottleSensorRangeHi
TPS Sensor malfunction
26
ETCSticking
ETC driver signal wire is open or the throttle plate is sticking
inside the throttle body
27
PredictedTPSDifference
TPS1 is different than calculated position
28
ETCSpringTestFailed
Throttle return spring failed keyup test
29
ETCDriverFault
Throttle driver over-current or driver signals shorted
33
MapSensorInputLow
MAP signal disconnected or open circuit
34
MapSensorInputHigh
MAP signal shorted or sensor failure
37
IATSensorInputLow
TMAP sensor failure or shorted circuit
38
IATSensorInputHigh
TMAP disconnected or IAT signal open
42
EST1Low
Coil driver signal low or under current
43
EST1High
Coil driver signal high or over current
52
LowOilPressure
Low engine oil pressure
53
BatterySensorInputLow
Battery voltage measured below 8.0 VDC
54
BatterySensorInputHigh
Battery voltage measured above 15.9 VDC
55
XDRPSensorInputLow
Measured sensor transducer power is below 4.6 VDC
56
XDRPSensorInputHigh
Measured sensor transducer power is above 5.2 VDC
57
Engine OverSpeed
RPM increased above maximum rpm setpoint
61
Pedal1SensorInputLo
APP1 signal disconnected, open circuit or sensor malfunction
62
Pedal1SensorInputHi
APP1 sensor failure or shorted circuit
63
Pedal1SensorRangeLo
APP1 potentiometer malfunction
64
Pedal1SensorRangeHi
APP1 potentiometer malfunction
65
Pedal2SensorInputLo
APP2 sensor failure or shorted signal
66
Pedal2SensorInputHi
APP2 signal disconnected, open circuit or sensor malfunction
67
Pedal2SensorRangeLo
APP2 potentiometer malfunction
68
Pedal2SensorRangeHi
APP2 potentiometer malfunction
69
Pedal1ToPedal2Difference
Measured APP2 pedal position signal is different than APP1
signal
71
AFRTrimValveOutput
FTV modulation driver signal fault
72
AFRTrimValveLowerDC
FTV duty cycle at lower (LEAN) limit
73
AFRTrimValveUpperDC
FTV duty cycle at upper (RICH) limit
74
O2SensorSwitching
O2 sensor not switching across the reference AFR voltage
77
OxygenSensorInputHigh
O2 sensor signal shorted to +5 VDC
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