Daewoo LIFT TRUCK Fault Codes

SUBJECT:TIER II FUEL SYSTEM FAULT CODES ANDMANUALS
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 forvery simpletroubleshooting 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.

Daewoo LIFT TRUCK 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 theSmall Engine Control Module (SECM).

Displaying the fault codes:
To display the fault codes:

1. Turn the ignition key on without cranking theengine.
2. Depress the accelerator pedal to the floor three times within fiveseconds.

Clearing the fault codes:
To clear the fault codes:

1. Turn the ignition key on without cranking theengine.
2. Depress the accelerator pedal to the floor ten times within fiveseconds.

Note: Do not clear the codes until the faults have been diagnosed and corrected.

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 existand 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:
Someof 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 conditionexists.

Daewoo LIFT TRUCK Fault Codes 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 thefault 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 versionsof 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 serialnumber.