1A-50 Engine Control System (4HK1)
Scan Tool Does Not Power Up
Circuit Description
The data link connector (DLC) is a standardized 16-
cavity connector. Connector design and location is
dictated by an industry wide standard, and is required
to provide the following:
• Scan tool power battery positive voltage at
terminal 16.
• Scan tool power ground at terminal 4.
• Common signal ground at terminal 5.
The scan tool will power up with the ignition OFF. Some
modules however, will not communicate unless the
ignition is ON.
Schematic Reference:
Engine Controls Schematics
Connector End View Reference:
Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing Scan Tool Does Not Power Up
Step
Action
Value(s)
Yes
No
1
Important
: Make sure the scan tool and 24 volts
adapter works properly on another vehicle before
using this chart.
1.
Turn OFF the ignition.
2.
Inspect the ROOM LAMP, AUDIO (15A) fuse
in the cab.
Is the ROOM LAMP, AUDIO (15A) fuse open?
—
Go to Step 2
Go to Step 3
2
Replace the ROOM LAMP, AUDIO (15A) fuse. If
the fuse continues to open, repair the short to
ground on one of the circuits that is fed by the
ROOM LAMP, AUDIO (15A) fuse or replace the
shorted attached component.
Did you complete the repair?
—
Go to Step 7
—
3
1.
Check each circuit at the data link connector
(DLC) (B-31) for a backed out, spread or
missing terminal.
2.
Repair the terminal as necessary.
Did you find and complete the repair?
—
Go to Step 7
Go to Step 4
4
Connect a test lamp between the +B circuit (pin 16
of B-31) at the DLC and a known good ground.
Does the test lamp illuminate?
—
Go to Step 6
Go to Step 5
5
Repair the open in the battery voltage circuit to the
DLC.
Did you complete the repair?
—
Go to Step 7
—
6
1.
Test each ground circuit at the DLC (pins 4
and 5 of B-31) for an open circuit or high
resistance.
2.
Repair the circuit(s), clean or tighten ground
as necessary.
Did you find and correct the condition?
—
Go to Step 7
Go to Intermittent
Conditions
7
1.
Connect the scan tool to the DLC.
2.
Attempt to turn ON the scan tool.
Does the scan tool ON?
—
System OK
Go to Step 1
LG4HKED-WE-0871.book 50
ページ
2007年11月29日 木曜日 午後6時29分
Содержание 2008MY N Series
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