1A-312 Engine Control System (4HK1)
DTC U0101 (Flash Code 85)
Circuit Description
The ECM and the transmission control module (TCM)
communicate control and diagnostic information via a
controller area network (CAN) communication bus. The
ECM monitors CAN operational status by expecting a
constant flow of messages from each module. If the
ECM fails to receive an expected message from the
TCM, this DTC will set.
Condition for Running the DTC
• DTC U0073 is not set.
• The battery voltage is more than 20 volts.
• The ignition switch is ON.
Condition for Setting the DTC
• The ECM detects that the CAN Bus messages
from the TCM are not being received.
Action Taken When the DTC Sets
• The ECM illuminates the SVS lamp when the
diagnostic runs and fails. Refer to DTC Type
Definitions for Action Taken When the DTC Sets -
Type C. (Euro 4 specification)
• The ECM illuminates the MIL when the diagnostic
runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
(Except Euro 4 specification)
• The ECM blinks the exhaust brake indicator lamp
when the diagnostic runs and fails.
• The ECM limits fuel injection quantity.
• The ECM inhibits exhaust brake control.
Condition for Clearing the DTC
• Refer to DTC Type Definitions for Condition for
Clearing the SVS Lamp/ DTC - Type C. (Euro 4
specification)
• Refer to DTC Type Definitions for Condition for
Clearing the MIL/ DTC - Type A. (Except Euro 4
specification)
Diagnostic Aids
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing DTC U0101
Step Action Value(s) Yes No
1
Did you perform the Diagnostic System Check
- Engine Controls?
—
Go to Step 2
Go to Diagnostic
System Check -
Engine Controls
2
1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the DTC Information with a scan tool.
Is DTC U0073 or U0110 also set?
—
Go to Applicable
DTC Go to Step 3
3
Attempt to communicate with the transmission
control module (TCM) via the transmission data
table.
Does the scan tool communicate with the
TCM?
—
Go to Step 4
Go to Diagnostic
System Check -
Transmission
Controls in Section
5A Transmission
Control System
4
1. Turn OFF the ignition.
2. Disconnect the TCM harness connector.
3. Measure the resistance across the CAN Low
and High circuits (pins 12 and 13 of B-112).
Is the resistance within the specified value
(parallel resistance of the 120 Ω resistor in the
ECM and the IP cluster should be 60 Ω)?
50 to 70 Ω
Go to Step 9 Go to Step 5
5
1. Leave the DMM connected to the TCM
harness connector.
2. Disconnect the IP cluster harness connector.
Is the resistance within the specified value?
110 to 130 Ω
Go to Step 6 Go to Step 7
LG4HKED-WE-0871.book 312 ページ ２００７年１１月２９日 木曜日 午後６時２９分
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