6
vehicle’s normal operation, the
MAP is estimated: an approximate
value of the manifold pressure is
therefore visualised on the
SEQUENT 24 interface.
For the self-MAPPING the MAP
sensor is provided with the pipes
necessary for the connection on the
vehicle, inside the SEQUENT 24
CALIBRATION KIT
Code
09SQ10990001.
2.9 HARNESS
The SEQUENT 24 harness is slen-
derer than the previous systems’
ones. The 56-pole connector har-
ness of the Standard SEQUENT is
replaced by the 24-pole connector
harness of the SEQUENT 24. To
make installation easier the main
devices of the system are connec-
ted through a specific connector
and the quantity of wires to weld is
very small.
Shielded conductors have been
used in order to comply with the
EMC standards. The connectors on
the harness are waterproof with the
exception of the connector of the
changeover switch that is however
housed in the passenger’s com-
partment and is therefore protected
from water. The injectors ought to
be cut with great care: the injectors
cut is the main novelty of the whole
system and of the harness.
2.9.1 I
NJECTORS CUT
Unlike the previous systems, the
injectors are cut on the positive:
this allows having less wires ente-
ring the ECU.
Two wires are actually enough to
cut all the injectors: the
White/Green wire (injectors positi-
ve, original equipment side) and the
White/Brown wire (injectors positi-
ve, injectors side).
On the other hand, it won’t be pos-
sible to change over from petrol to
gas and vice versa injector by injec-
tor; the changing over could possi-
bly be abrupt and we might change
over only while decelerating on
some vehicles.
The White/Green wire has also the
key contact positive function, i.e. it
is the wire that turns the gas ECU
ON. It is proper to bear in mind, in
this connection, that some vehicles
do not actuate the injectors positive
until the starting up: it is not the-
refore sufficient to turn the key con-
tact on. In this case, the only way to
turn the gas ECU on is to start up.
As while programming, the gas
ECU needs this wire to be high-
potential, programming will be car-
ried out with the vehicle running.
The injectors positive normally is
not low-potential as soon as the
engine and the key contact are
switched off, but it can remain high
for some seconds with the vehicle
switched off. In this case, the ECU
too will remain ON for some
seconds.
The White/Brown wire is directly
connected with the petrol injectors.
It supplies tension on the injectors
positive while running on petrol,
whereas it takes this power supply
off while running on gas, in order to
cut injectors.
It is highly recommended to use
right and left harnesses specifically
conceived for Sequent 24 whene-
ver it is possible. They actually
allow making quick connections
with the injectors, without welding
and cutting down any error possibi-
lity.
It is necessary not to mix up the
right with the left harnesses and to
carefully follow the instructions sup-
plied with these harnesses.
The exchange of the two harnesses
brings about the vehicle’s malfunc-
tion both on petrol and on gas and
the short-circuit of the injectors pilo-
ting outputs of the petrol ECU to
the positive. This short-circuit
strains the petrol ECU only when
the engine is running (it is anyway
not possible to start up).
Furthermore, the petrol ECU is
generally protected against this
type of short circuit. Nonetheless it
is recommended to act very cau-
tiously. In particular, it is recom-
mended not to insist excessively if
the vehicle does not start up after
reconnecting the injectors, but to
check immediately whether the
connection harness is correct.
Should the right and left harnesses
not be used, it is anyway possible
to use the universal harness, fol-
lowing the enclosed instructions
with the utmost care.
In particular, bear in mind that:
- The White/Green wire can be
generally connected only with a
positive wire coming from the petrol
original harness, even if it is best, in
general, to reunify all the positives
of the injectors (ECU side) on this
wire, in order not to supply overcur-
rent to one single wire of the petrol
original harness.
- All the positives of the petrol injec-
tors ought to be cut, by disconnec-
ting them from the original positive
and connected only with the
White/Brown wire. Indeed, should
the original positive still get to a
petrol injector, the injector will also
work while running on gas and the-
refore provoke the bad combustion
of the attendant cylinder.
- The petrol injectors positive to be
cut ought to be as close as possible
to the petrol injectors. If we cut the
positive far from the petrol injectors,
we actually run the risk of cutting, in
addition to the injectors, other
actuators or sensors of the vehicle
supplied with the same wire of the
original equipment.
- The injectors negatives ought to
be cut and connected, as in the
past, to the violet (petrol ECU side)
and orange (injectors side) wires
and ought to be connected in the
same order, from 1 to 4, as the gas
injectors.
At the end of this handbook (Annex
