Daewoo CIELO EURO III, Manual

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ENGINE CONTROLS 1F – 83
DAEWOO T-154 BL2,3
DATA LINK CONNECTOR DIAGNOSIS
Circuit Description
The provision for communicating with the engine
control module (ECM) is the Data Link Connector
(DLC). It is located under the instrument panel.
The DLC is used to connect the scan tool.
Battery power and ground is supplied for the scan
tool through the DLC. The serial data circuit to the DLC
allows the ECM to communicate with the scan
tool.
Diagnostic Aids
Ensure that the correct application (model line, car year,
etc.) has been selected on the scan tool. If communica-
tion still cannot be established, try the scan tool on
another vehicle to ensure that the scan tool, or cables
are not the cause of the condition.
An intermittent may be caused by a poor connection,
rubbed through wire insulation, or a broken wire inside
the insulation.
Any circuitry that is suspected of causing an intermittent
complaint should be thoroughly checked for the follow-
ing conditions:
Backed-out terminals.
Improper mating of terminals.
Broken locks.
Improperly formed or damaged terminals.
Poor terminals to wiring connection.
Physical damage to the wiring harness.
Corrosion.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Table.
1. The Powertrain On-Board (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-
cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
3. Unlike the UART serial data circuit, the only time a
serial data circuit has any voltage on it is when a
scan tool asks the ECM for information and
sends the information out.
8. Locate and repair any shorts that may have caused
the fuse to open before replacement, if the no volt-
age condition was due to an open fuse.
11. The replacement ECM must be programmed.
Refer to the latest Techline procedure for ECM
reprogramming.
16. The scan tool or associated cables could be mal-
functioning. Refer to the scan tool’s manual for re-
pair information.
Data Link Connector Diagnosis
Step Action Value Yes No
1
Perform an On-Board Diagnostic (EOBD) System
Check.
Is the system check complete?
–
Go to Step 2
Go to “On-
Board Diag-
nostic System
Check”
2
1. Ignition ON, engine OFF.
2. Install the scan tool.
Does the scan tool power up?
–
Go to Step 3 Go to Step 4
3
1. Disconnect the scan tool.
2. With a test light connected to ground, probe the
serial data terminal 7 at the Data Link
Connector (DLC).
Does the test light remain OFF?
–
Go to Step 5 Go to Step 6
4
With the test light connected to ground, probe the
DLC battery feed circuit terminal 16.
Does the test light remain OFF?
–
Go to Step 8 Go to Step 7
5
With the test light connected to B+, probe the Class
II serial data terminal 7 at the DLC.
Does the test light remain OFF?
–
Go to Step 9 Go to Step 10