Daewoo Matiz (2003 year). Manual - part 32

1F – 38  ENGINE CONTROLS

MAA1F050

MAIN RELAY CIRCUIT CHECK

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 EF25 and EF26.
The Electronic Ignition (EI) system ignition coil is sup-
plied voltage through the engine fuse block fuse EF26.
The fuel injectors are supplied voltage through the en-
gine fuse block fuse EF25.

Diagnostic Aids

D

An intermittent problem may be caused by a poor
connection, rubbed through wire insulation, or a bro-
ken wire inside the insulation.

D

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 sup-
plied to these components, they will not operate.

ENGINE CONTROLS  1F – 39

Main Relay Circuit Check

Step

Action

Value(s)

Yes

No

1

1. Turn the ignition OFF.
2. Disconnect the engine fuse block fuse EF26.
3. Turn the ignition ON.
4. With a test light connected to the ground, probe

the fuse terminals nearest the main relay for fuse
EF19.

Is the light on at both terminal?

–

System OK

Go to Step 2

2

Is the light on at only one terminal?

–

Go to Step 3

Go to Step 4

3

Repair the open in the wiring between the main relay
connector terminal 30 and the fuse EF19 as needed.
Is the repair complete?

–

System OK

–

4

1. 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 and 30.

Is the light on at both terminals.

–

Go to Step 8

Go to Step 5

5

1. Turn the ignition OFF.
2. Check engine fuse block fuse EF19.
Is one or both fuse blown?

–

Go to Step 6

Go to Step 7

6

1. Repair short circuit between terminal 87 of main

relay and heated oxygen sensor

2. Replace fuse EF19.
Is the repair complete?

–

System OK

–

7

Repair open circuit between terminal 30 of main
relay and fuse EF19.
Is the repair complete?

–

System OK

Go to Step 8

8

1. Turn the ignition OFF.
2. Measure the resistance between following

terminals.

D

Terminal 86 of main relay and ground.

D

Terminal 87 of main relay and ground.

Is the resistance within the specified value

0 

Ω

Go to Step 10

Go to Step 9

9

Repair open circuit.
Is the repair complete?

–

System OK

–

10

Replace the main relay.
Is the repair complete?

–

System OK

–

1F – 40  ENGINE CONTROLS

MAA1F060

MANIFOLD ABSOLUTE PRESSURE CHECK

Circuit Description

The Manifold Absolute Pressure (MAP) sensor measure
the changes in the intake manifold pressure which result
from engine load (intake manifold vacuum) and rpm
changes. The MAP sensor converts these changes into
voltage output. The Engine Control Module (ECM) send
a 5-volt reference voltage to the MAP sensor. As the in-
take manifold pressure changes, the output voltage of

MAP sensor also changes. A low voltage (high vacuum)
output of 1 to 1.5 volts is present at idle. A high voltage
(low vacuum) output of 4.5 to 5.0 volts is present at wide
open throttle. The MAP sensor is also used under cer-
tain conditions to measure barometric attitude changes.
The ECM uses the MAP sensor for the delivery and igni-
tion timing changes.

ENGINE CONTROLS  1F – 41

Manifold Absolute Pressure Check

Step

Action

Value(s)

Yes

No

1

1. Turn the ignition OFF.
2. Connect a scan tool to the Data Link Connector

(DLC).

3. Turn the ignition ON.
4. Compare the Manifold Absolute Pressure (MAP)

sensor voltage reading from scanner with that
from known good vehicle.

Is the difference in the two voltage reading less than
the value specified?

0.4 V

Go to Step 2

Go to Step 5

2

1. Turn the ignition OFF.
2. Connect a scan tool to the DLC.
3. Disconnect the MAP sensor vacuum line.
4. Connect a hand vacuum pump to the Map sensor.
5. Turn the ignition ON.
6. Note the MAP sensor voltage.
7. Apply 34kPa (10 in. Hg) of vacuum to the Map

sensor and note the voltage change.

Is the difference in voltage readings more than the
value specified?

1.5 V

System OK

Go to Step 3

3

Inspect the MAP sensor connector terminals.
Is the problem found.

–

Go to Step 4

Go to Step 5

4

Repair the MAP sensor connector terminals as
needed.
Is the repair complete?

–

System OK

–

5

Replace the MAP sensor.
Is the repair complete?

–

System OK

–