Daewoo G15S-2, G18S-2, G20SC-2 Plus, GC15S-2, GC18S-2 Service Manual

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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

NONE

Signifies the end of one pass through the fault list

ECTSensorInputLow

Normally set if the coolant sensor wire is shorted to ground

ECTSensorInputHigh

Set if the coolant sensor wire is disconnected or open

ECTRangeHigh

Coolant sensor has measured an excessive temperature or shorted to GND

ThrottleSensorInputLo

TPS1 signal wire is open

ThrottleSensorInputHi

TPS1 signal wire is shorted

ThrottleSensorRangeLo

TPS Sensor malfunction

ThrottleSensorRangeHi

TPS Sensor malfunction

ETCSticking

ETC driver signal wire is open or the throttle plate is sticking inside the throttle body

PredictedTPSDifference

TPS1 is different than calculated position

ETCSpringTestFailed

Throttle return spring failed keyup test

ETCDriverFault

Throttle driver over-current or driver signals shorted

MapSensorInputLow

MAP signal disconnected or open circuit

MapSensorInputHigh

MAP signal shorted or sensor failure

IATSensorInputLow

TMAP sensor failure or shorted circuit

IATSensorInputHigh

TMAP disconnected or IAT signal open

EST1Low

Coil driver signal low or under current

EST1High

Coil driver signal high or over current

LowOilPressure

Low engine oil pressure

BatterySensorInputLow

Battery voltage measured below 8.0 VDC

BatterySensorInputHigh

Battery voltage measured above 15.9 VDC

XDRPSensorInputLow

Measured sensor transducer power is below 4.6 VDC

XDRPSensorInputHigh

Measured sensor transducer power is above 5.2 VDC

Engine OverSpeed

RPM increased above maximum rpm setpoint

Pedal1SensorInputLo

APP1 signal disconnected, open circuit or sensor malfunction

Pedal1SensorInputHi

APP1 sensor failure or shorted circuit

Pedal1SensorRangeLo

APP1 potentiometer malfunction

Pedal1SensorRangeHi

APP1 potentiometer malfunction

Pedal2SensorInputLo

APP2 sensor failure or shorted signal

Pedal2SensorInputHi

APP2 signal disconnected, open circuit or sensor malfunction

Pedal2SensorRangeLo

APP2 potentiometer malfunction

Pedal2SensorRangeHi

APP2 potentiometer malfunction

Pedal1ToPedal2Difference

Measured APP2 pedal position signal is different than APP1 signal

AFRTrimValveOutput

FTV modulation driver signal fault

AFRTrimValveLowerDC

FTV duty cycle at lower (LEAN) limit

AFRTrimValveUpperDC

FTV duty cycle at upper (RICH) limit

O2SensorSwitching

O2 sensor not switching across the reference AFR voltage

OxygenSensorInputHigh

O2 sensor signal shorted to +5 VDC

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