Range Rover P38
19
FUEL SYSTEM
NEW RANGE ROVER
56
DESCRIPTION AND OPERATION
A diagnostic routine is used to measure both sensor
heater current and the heater supply voltage so its
resistance can be calculated. The function is active
once per drive cycle as long as the heater has been
switched on for a pre-defined period and the current
has stabilised. The PWM duty cycle is carefully
controlled to prevent thermal shock to cold sensors.
On NAS vehicles, the catalysts are monitored to
determine emission pollutant conversion efficiency;
the following fault codes will be generated by the ECM
diagnostics, which can be retrieved by Testbook:
•
P0420 - Catalyst efficiency deteriorated LH bank
•
P0430 - Catalyst efficiency deteriorated RH bank
See EMISSION CONTROL, Description and
operation.
Fuel pump relay - from 99MY
The fuel pump relay is fitted in the engine
compartment fusebox which is situated at the front
right hand side of the engine compartment. The relay
is a four-pin normally open type, encapsulated in a
yellow plastic housing.
The fuel supplied to the injectors from the in-tank fuel
pump is controlled by the ECM via the fuel pump
relay. During engine cranking, the fuel pump relay is
activated by the ECM allowing the fuel system to be
pressurised to 3.5 bar (52 lbf.in
2
). The pump relay is
then deactivated until engine start has been achieved.
Battery voltage is supplied via the engine
compartment fusebox and relay activation is achieved
by ground path switching through the ECM.
If the fuel pump relay should fail, the following
symptoms may be observed:
•
Engine stalls or will not start
•
No fuel pressure at the fuel injectors
A fuel pump relay failure is likely to occur for the
following reasons:
•
Relay drive open circuit
•
Short circuit to vehicle supply or ground
•
Component failure
If the fuel pump relay should fail, the following fault
codes will be generated by the ECM diagnostics,
which can be retrieved by Testbook:
•
P1230 - Fuel pump relay open circuit - not the
fuel pump itself
•
P1231 - Fuel pump relay short circuit to battery
supply - not the fuel pump itself
•
P1232 - Fuel pump relay short circuit to ground -
not the fuel pump itself