Infiniti Q45 (FY33). Manual - part 91

SBR366E

CHECK COMMUNICATION FAILURE
(when cranking engine).

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

1. Erase ABS/TCS control unit and TAC

module problem memory.

2. Turn ignition switch to “OFF”, then to

“ON”. (Do not start engine.)

3. Perform self-diagnostic procedures for

TAC module.

4. Does only “THRL POS/S-2 SIG” (self-

diagnostic item) appear on display?

Yes

(See next page.)

CHECK COMMUNICATION SYSTEM,
HARNESSES AND CONNECTORS.

1. Disconnect ABS/TCS control unit and

TAC module connectors.

2. Check continuity between connector

terminals.

Continuity should exist.

Check the following.

Harness connectors

B103

F75

Harness for open or
short between TAC mod-
ule connector and ABS/
TCS control unit connec-
tor

If NG, repair harness or
connectors.

Connect connectors, then repeat self-diag-
nostic procedures to ensure that “TAC
module communication” and “THRL POS/
S-2 SIG” appear on display using ABS/
TCS control unit respectively.

Yes

No items appear on dis-
play. This completes
inspection procedures. If
any other item appears on
display, repair or replace
affected item.

CHECK ABS/TCS CONTROL UNIT
TRANSMISSION CIRCUIT.

Disconnect TAC module connector.

Check waveform pattern and voltage*
between TAC module connector terminal

and body ground immediately after

turning ignition switch to “ON”.
Waveform pattern and voltage are
indicated in ABS/TCS control unit
inspection table. Refer to BR-123.

Faulty ABS/TCS control
unit. (Voltage held to 0V or
7V, min.)

*: Communication output sig-

nal is suspended 5 seconds
after ignition switch is
turned “ON”.

(Go to next page.)

ABS/TCS control unit

TAC module

IDX

TROUBLE DIAGNOSES FOR SELF-DIAGNOSTIC ITEMS

Diagnostic Procedure 2 (TCM COMM: TAC
module communication) (Cont’d)

BR-81

SBR644D

CHECK ABS/TCS CONTROL UNIT
RECEIVER CIRCUIT AND TAC MODULE
TRANSMITTER-RECEIVER CIRCUITS.

Connect TAC module connector.

Turn ignition switch “ON”.

Immediately after ignition switch is
turned “ON”, are waveform pattern and
voltage* between TAC module connector
terminals

and body ground as

shown in the figure at left?

Yes

Faulty TAC module. (When
pulse output is observed
only at terminal

and

voltage at terminal

held to 0V or more than
7V, or no pulse output is
observed at terminal

*: Output signal is suspended

5 seconds after ignition
switch is turned “ON”.

Faulty ABS/TCS control unit.

Start engine. Wait for at least 5
seconds, then perform self-diagnostic
procedures for TAC module. Does
“THRL POS/S-2 SIG” then appear on
display?

Yes

Immediately after turning
ignition switch “OFF”, re-
start engine and wait for at
least 5 seconds. Perform
self-diagnostic procedures
for TAC module. If “THRL
POS/S-2 SIG” does not
appear on display, ABS/
TCS control unit-TAC mod-
ule communication line is
functioning properly. If
“THRL POS/S-2 SIG”
appears, go to step “

”.

Perform self-diagnostic procedures for
TCS/ABS control unit. Ignition switch
must be “ON”.

Does indication other than “TCM
COMM” appear under self-diagnostic
items on display?

Yes

Voltage drop while crank-
ing engine.

Faulty ABS/TCS control
unit and TAC module
power source system.

Repair or replace affected parts with new
ones. Then, erase trouble codes for ABS/
TCS control unit and/or TAC module from
memory. Start engine and repeat self-di-
agnostic procedures.

TROUBLE DIAGNOSES FOR SELF-DIAGNOSTIC ITEMS

Diagnostic Procedure 2 (TCM COMM: TAC
module communication) (Cont’d)

BR-82

SBR036EA

Diagnostic Procedure 3 (Engine speed signal)

Code No. 80 of ABS/TCS control unit

SBR368E

Self-diagnostic item “ENGINE SPEED
SIG” appears on display.

1. Perform self-diagnostic procedures for

ECM.

2. Does “CAM POS SEN/CIR”* (self-diag-

nostic item) appear on display?

Yes

Check ECM.
Refer to EC section,
“TROUBLE DIAGNOSES”.

*: Out of ECM diagnostic

items, only “CAM POS
SEN/CIR” causes TCS to
be suspended (TCS OFF
indicator “ON” and SLIP
indicator “ON”) and allows
ABS/TCS control unit to
indicate “ENGINE SPEED
SIG”.

Perform self-diagnostic procedures for
ECM.
Do “ECM-ABSTCS COMM NG” and “ABS-
TCS C/U SIGNAL”* (self-diagnostic items)
appear on display?

Yes

Go to diagnostic proce-
dures 4, 5, 6.

Disconnect* ABS/TCS control unit and
ECM connectors, then reconnect them
securely. Repeat self-diagnostic proce-
dures.

Poor connector contact.

*: Check for terminal

separation, looseness or
bending, etc., at connector
housing. If necessary, repair
faulty terminals.

CHECK ABS/TCS CONTROL UNIT-TO-
ECM HARNESS CONNECTORS.

1. Disconnect ABS/TCS control unit and

ECM connectors.

2. Check continuity between terminal

for ABS/TCS control unit and terminal

for ECM.

Continuity should exist.

Check the following.

Harness connectors

F69

B103

Harness for open or
short between ECM con-
nectors and ABS/TCS
control unit

If NG, repair harness or
connectors.

Connect connectors, then repeat self-diag-
nostic procedures.

IDX

TROUBLE DIAGNOSES FOR SELF-DIAGNOSTIC ITEMS

BR-83

SBR038EA

Diagnostic Procedure 4 (LAN SIGNAL 1: LAN
monitoring)

Code No. 83 of ABS/TCS control unit

SBR367E

Self-diagnostic item “LAN SIGNAL 1”
appears on display.

Perform self-diagnostic procedures for
ECM.
Does self-diagnostic item “ECM-ABSTCS
COMM NG” appear on display?

Yes

(See below.)

Does “ABS-TCS C/U SIGNAL” appear on
display?

Yes

Faulty ABS/TCS control
unit.

Do any other ABS/TCS control unit self-
diagnostic items appear on display?

Yes

Repair or replace affected
items shown on display.

Check if battery voltage is too low (less
than 9V) or battery terminals are loose.

Repair or replace battery
and power source parts.

Repeat self-diagnostic procedures.

Faulty ABS/TCS control
unit.

LAN CIRCUIT CHECK

Check continuity between connector termi-
nals.

Continuity should exist.

Check the following.

Harness connectors

B103

F69

Harness for open or
short between ECM con-
nector and ABS/TCS
control unit

Harness for open or
short between ABS/TCS
control unit connector
and TCM connector

Harness for open or
short between ECM con-
nector and TCM connec-
tor

If NG, repair harness or
connectors.

Repeat self-diagnostic procedures.

ABS/TCS

control unit

ECM

TCM

TROUBLE DIAGNOSES FOR SELF-DIAGNOSTIC ITEMS

BR-84

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