Page 313 of 2643
ENGINE CONTROLS 1F – 67
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
111. Replace the fuse F2 or repair the wire between
the fuel pump relay connector terminal 30 and
the battery.
2. Install the fuel pump relay.
3. Turn the ignition OFF for 10 seconds.
4. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
121. Turn the ignition OFF.
2. Replace the ECM.
3. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
131. Replace the fuse F2 or repair the wire between
the fuel pump relay connector terminal 30 and
the ignition system
2. Install the fuel pump relay.
3. Turn the ignition OFF for 10 seconds.
4. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
Page 314 of 2643

1F – 68IENGINE CONTROLS
DAEWOO V–121 BL4
FUEL PUMP RELAY CIRCUIT CHECK (1.8L DOHC)
Circuit Description
When the ignition switch is turned ON, the Engine Control
Module (ECM) will supply battery voltage to activate the
fuel pump relay and run the in–tank fuel pump. The fuel
pump will operate as long as the engine is cranking or run-
ning and the ECM is receiving ignition reference pulses.
If there are no reference pulses, the ECM will shut off the
fuel pump within 2 seconds after the ignition switch is
turned ON.
Diagnostic Aids
An intermittent problem may be caused by a poor connec-
tion, rubbed through wire insulation, or a broken wire in-
side the insulation.Test Description
The number(s) below refer to step(s) on the diagnostic
table.
3. This step checks for the ECM providing a ground
for the operation of the fuel pump relay.
7. By confirming that the wiring is OK using Steps 2
through 6, it can be determined that the fuel pump
relay is at fault.
9. After determining that there is no ground being pro-
vided by the ECM to the fuel pump relay, the fault is
either the ECM or the wiring between the ECM and
the fuel pump relay.
Page 315 of 2643

ENGINE CONTROLS 1F – 69
DAEWOO V–121 BL4
Fuel Pump Relay Circuit Check (1.8L DOHC)
StepActionValue(s)YesNo
11. Turn the ignition OFF for 10 seconds.
2. Turn the ignition ON.
3. Listen for in–tank fuel pump operation.
Does the fuel pump operate for the time specified?2 secSystem OKGo to Step 2
21. Turn the ignition OFF.
2. Disconnect the fuel pump relay.
3. Connect a test light between the fuel pump
relay connector terminal 30 and ground.
Turn the ignition ON. Is the test light on?–Go to Step 3Go to Step 8
31. Turn the ignition OFF.
2. Connect a test light between the fuel pump
relay connector terminal 85 and battery posi-
tive.
3. Turn the ignition ON.
4. With the ignition ON, the test light should light
for the time specified.
Is the test light on?2 secGo to Step 4Go to Step 9
41. Turn the ignition OFF.
2. Connect a test light between the fuel pump
relay connector terminal 30 and ground.
Is the test light on?–Go to Step 5Go to Step 11
5Check for an open or short to ground in the wire be-
tween the fuel pump relay connector terminal 87 and
the fuel pump connector terminal 3.
Is the problem found?–Go to Step 6Go to Step 7
61. Repair the wire between the fuel pump relay
connector terminal 87 and the fuel pump con-
nector terminal 3.
2. Install the fuel pump relay.
3. Turn the ignition OFF for 10 seconds.
4. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
71. Replace the fuel pump relay.
2. Turn the ignition OFF for 10 seconds.
3. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
8Check for an open wire between the fuel pump relay
connector terminal 30 and the battery.
Is the problem found?–Go to Step 13–
9Check for an open wire between the fuel pump relay
connector terminal 85 to the engine control module
(ECM) connector terminal K54
Is the problem found.–Go to Step 10Go to Step 12
101. Repair the wire between the fuel pump relay
connector terminal 85 to the ECM connector
terminal K54.
2. Install the fuel pump relay.
3. Turn the ignition OFF for 10 seconds.
4. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
Page 316 of 2643
1F – 70IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
111. Replace the fuse Ef18 or repair the wire be-
tween the fuel pump relay connector terminal
30 and the battery.
2. Install the fuel pump relay.
3. Turn the ignition OFF for 10 seconds.
4. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
121. Turn the ignition OFF.
2. Replace the ECM.
3. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
131. Replace the fuse Ef18 or repair the wire be-
tween the fuel pump relay connector terminal
30 and the ignition system
2. Install the fuel pump relay.
3. Turn the ignition OFF for 10 seconds.
4. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
Page 317 of 2643

ENGINE CONTROLS 1F – 71
DAEWOO V–121 BL4
MAIN RELAY CIRCUIT CHECK (1.4L/1.6L DOHC)
Circuit Description
When the ignition is turned On or to the START position,
the main relay is energized. The main relay then supply
voltage to the engine fuse block fuse Ef11. The Electronic
Ignition (EI) system ignition coil, Evaporative Emission
(EVAP) Canister Purge Solenoid and Heated Oxygen
Sensor (HO2S) are supplied voltage through the engine
fuse block fuse Ef11. The fuel injectors are supplied volt-
age through the engine fuse block fuse Ef11.Diagnostic Aids
S An intermittent problem may be caused by a poor
connection, rubbed through wire insulation, or a
broken wire inside the insulation.
S A fault main relay will cause a no start condition.
There will be no voltage supplied to the EI system
ignition coil, or the fuel injectors. Without voltage
supplied to these components, they will not oper-
ate.
Main Relay Circuit Check (1.4L/1.6L DOHC)
StepActionValue(s)YesNo
11. Turn the ignition OFF.
2. Disconnect the engine fuse block fuse Ef11.
3. Turn the ignition ON.
4. With a test light connected to the ground,
probe the fuse terminals nearest the main relay
for fuse Ef11.
Is the light on at both terminal?–System OKGo to Step 2
2Is the light on at only one terminal?–Go to Step 3Go to Step 4
3Repair the open in the wiring between the main relay
connector terminal 87 and the fuse Ef11.
Is the repair complete?–System OK–
Page 318 of 2643
1F – 72IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
41. Turn the ignition OFF.
2. Remove the main relay.
3. Turn the ignition ON.
4. With a test light connected to the ground,
probe the main relay terminals 85.
Is the light on at both terminals.–Go to Step 6Go to Step 5
51. Turn the ignition OFF.
2. Measure the resistance between following ter-
minals.
S Terminal 86 of main relay and ground.
Is the resistance within the specified value0 WGo to Step 7Go to Step 6
6Repair open circuit.
Is the repair complete?–System OK–
7Replace the main relay.
Is the repair complete?–System OK–
Page 319 of 2643

ENGINE CONTROLS 1F – 73
DAEWOO V–121 BL4
MAIN RELAY CIRCUIT CHECK (1.8L DOHC)
Circuit Description
When the ignition is turned On or to the START position,
the main relay is energized. The main relay then supply
voltage to the engine fuse block fuse F2. The Electronic
Ignition (EI) system ignition coil, Evaporative Emission
(EVAP) Canister Purge Solenoid and Heated Oxygen
Sensor (HO2S) are supplied voltage through the engine
fuse block fuse F2. The fuel injectors are supplied voltage
through the engine fuse block fuse F2.Diagnostic Aids
S An intermittent problem may be caused by a poor
connection, rubbed through wire insulation, or a
broken wire inside the insulation.
S A fault main relay will cause a no start condition.
There will be no voltage supplied to the EI system
ignition coil, or the fuel injectors. Without voltage
supplied to these components, they will not oper-
ate.
Main Relay Circuit Check (1.8L DOHC)
StepActionValue(s)YesNo
11. Turn the ignition OFF.
2. Disconnect the I/P fuse block fuse F2.
3. Turn the ignition ON.
4. With a test light connected to the ground,
probe the fuse terminals nearest the ignition
relay for fuse F2.
Is the light on at both terminal?–System OKGo to Step 2
2Is the light on at only one terminal?–Go to Step 3Go to Step 4
3Repair the open in the wiring between the ignition
relay connector terminal 87 and the fuse F2.
Is the repair complete?–System OK–
Page 320 of 2643
1F – 74IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
41. Turn the ignition OFF.
2. Remove the ignition relay.
3. Turn the ignition ON.
4. With a test light connected to the ground,
probe the ignition relay terminals 85.
Is the light on at both terminals.–Go to Step 6Go to Step 5
51. Turn the ignition OFF.
2. Measure the resistance between following ter-
minals.
S Terminal 86 of main relay and ground.
Is the resistance within the specified value0 WGo to Step 7Go to Step 6
6Repair open circuit.
Is the repair complete?–System OK–
7Replace the ignition relay.
Is the repair complete?–System OK–