1Engine and peripherals
V1 MR-376-X76-13B000$TOC.mif
V1
13B
"The repair procedures given by the manufacturer in this document are based on the
technical specifications current when it was prepared.
The procedures may be modified as a result of changes introduced by the
manufacturer in the production of the various component units and accessories from
which his vehicles are constructed."
V1
All rights reserved by Renault s.a.s.
Edition Anglaise
Copying or translating, in part or in full, of this document or use of the service part
reference numbering system is forbidden without the prior written authority of
Renault s.a.s.
© Renault s.a.s. 2013
DIESEL INJECTION
DCM 1.2 Injection
Program no.: 4C
Vdiag No.: 08
Fault finding – Introduction 13B - 2
Fault finding – Cleanliness guidelines 13B - 7
Fault finding – System operation 13B - 10
Fault finding – Replacement of components 13B - 17
Fault finding – Configurations and programming 13B - 21
Fault finding – Fault summary table 13B - 22
Fault finding – Interpretation of faults 13B - 25
Fault finding – Conformity check 13B - 119
Fault finding – Status summary table 13B - 135
Fault finding – Interpretation of statuses 13B - 136
Fault finding – Parameter summary table 13B - 141
Fault finding – Interpretation of parameters 13B - 143
Fault finding – Command summary table 13B - 145
Fault finding – Customer complaints 13B - 148
Fault finding – Fault Finding Chart 13B - 150
Fault finding – Tests 13B - 186
13B-12V1 MR-376-X76-13B000$030.mif
DIESEL INJECTION
Fault finding – System operation13B
DCM 1.2 Injection
Program no.: 4C
Vdiag No.: 08
Idling speed regulation
The computer handles the calculation of idling speed. This has to take account of the instantaneous power level to
be supplied, according to the following factors:
– engine coolant temperature,
– gear ratio engaged,
– battery charge,
– electrical consumers (Additional heating, Air conditioning, Fan Unit, electric windows, etc.) active or inactive,
– system faults detected.
Individual injector correction (C2I)
The DCM 1.2 system injectors must be calibrated with correction values so that their flow may be adjusted precisely.
Each injector is calibrated for different pressures on a test bench, and its specifications are shown on a label
attached to the body of the injector holders. These individual correction values are then entered into the computer
EEPROM, which can then control the injectors, taking their manufacturing variations into account.
Measuring the angular position (Cylinder reference sensor)
The angular position is measured using a magneto-inductive sensor triggered by machined teeth on the shaft
flywheel. This flywheel has sixty teeth separated by six degrees minus two missing teeth, that form a notch.
A second sensor (Hall effect) triggered by a machined tooth on the high pressure pump drive pulley (synchronised
with the camshaft), which rotates at half the engine speed, supplies an injection cycle running signal. By comparing
the signals from these two sensors, the computer's APS module (Angular Position Subsystem) is able to supply the
synchronisation components to the system assembly, namely:
– the angular position of the flywheel
– the speed and number of the active injector
– the injection cycle progress.
This module also supplies the system with the engine speed signal.
Flow capacity function (VLC)
Because of the combination of several parameters such as the diesel fuel temperature, part wear, clogging of the
diesel filter etc., the system limit may be reached during its service life. If this happens, the rail pressure cannot be
maintained because the pump lacks the necessary capacity. If the pump lacks the necessary capacity, this
programming will therefore reduce the requested flow to a value that will enable the pressure monitoring system to
control the pressure again.
The customer may have noticed a loss of vehicle performance when this program is activated (confirmed by status
Flow capacity function). This is part of normal operation.
