Land Rover Engine Management Systems Rover Manual

13/14CU AND 14CUX SYSTEMS
13/14CU and 14CUX Systems 79
13/14CU AND 14CUX SYSTEMS
Introduction
Three variations of similar Lucas engine management systems have been used on Land Rover 
vehicles from 1987 to selected 1995 models.  Operation of each of these systems is 
fundamentally the same, the differences between each being enhancements to self diagnostics, 
improved adaptability to operating conditions, and additional input/output capability.  All of these 
systems utilize a Engine Control Module, and...

13/14CU AND 14CUX SYSTEMS
80 The following are 13 CU outputs:
•  Fuel Injectors
•  Idle Air Control Valve (IACV)
•  Malfunction Indicator Lamp (MIL)
•  Fuel Pump/ Oxygen Sensor Heaters Relay
•  Main relay
13CU System Inputs and Outputs 

13/14CU AND 14CUX SYSTEMS
13/14CU and 14CUX Systems 81 14CU and 14CUX
The 14CU and 14CUX modules include additional inputs and output controls for more precise 
control of the air-fuel mixture and enhanced self-diagnostic capabilities.
The following are ECM inputs:
•  Key on
•  Battery voltage
•  Throttle Position Sensor (TPS)
•  Engine speed
•  Engine Fuel Temperature (EFT) sensor
•  Engine Coolant Temperature Sensor (ECT)
•  Heated Front Screen
•  Heated Oxygen Sensor (HO2S)
•  Mass Air Flow Sensor...

13/14CU AND 14CUX SYSTEMS
8214CUX Inputs and Outputs 

13/14CU AND 14CUX SYSTEMS
13/14CU and 14CUX Systems 83 SYSTEM INPUTS
Mass Air Flow Sensor (MAF)
The Mass Air Flow (MAF) sensor is a hot-wire type.  It contains two wires, one heated to a 
known value of 100° C (212° F) above the other.  As air flow increases, the current required to 
maintain this difference in temperature increases.  The air flow meters circuitry converts this 
current requirement into a signal the ECM uses to determine the amount of air entering the 
intake manifold.
Typical MAF output...

13/14CU AND 14CUX SYSTEMS
84 Throttle Position Sensor (TPS)
This potentiometer is mechanically linked to the throttle butterfly and provides an output voltage 
proportional to the butterfly position.   This information allows the ECM to determine throttle 
position and is used for ECM strategies like the following:
•  Acceleration Enhancement - The ECM increases the amount of fuel normally provided for a 
given throttle position during periods of peak acceleration.  This allows the system to antici-
pate...

13/14CU AND 14CUX SYSTEMS
13/14CU and 14CUX Systems 85 Engine Coolant Temperature Sensor (ECTS)
The ECTS is a resistor based sensor.  As coolant temperature increases, sensor resistance 
decreases.  The ECM uses this information for hot- and cold-start strategies that require 
additional fuel delivery.  It also uses this information to help determine when to enter closed loop 
operation.
A diagnostic trouble code (14) is stored when the signal is out of range (0.15V to 4.9V) for 
longer than 160...

13/14CU AND 14CUX SYSTEMS
86 Heated Oxygen Sensor (HO2S)
The heated oxygen sensor is mounted in each exhaust downpipe and is used by the ECM to 
determine whether the engine is operating rich or lean.  The ECM uses this information to 
increase or decrease injector pulse width to bring the air/fuel ratio as close to Stoichiometric as 
possible.  The ECM monitors each sensor separately and makes fuel trim adjustments to each 
cylinder bank independent of the other.
Typical Heated Oxygen Sensor
Oxygen...

13/14CU AND 14CUX SYSTEMS
13/14CU and 14CUX Systems 87 Park/Neutral Position Switch (PNPS)
The ECM uses this information on transmission gear selection to determine correct positioning 
of the Idle Air Control (IACV) valve.  A diagnostic trouble code (69 [14CUX only]) is set when 
sensor voltage is 5 V during cranking or 0 V with RPM above 2663 and MAFS voltage above 3 
V.   
Engine Speed
The ECM determines engine speed from data received through the negative coil lead.  A 
dropper resistor (6800 ohms)...

13/14CU AND 14CUX SYSTEMS
88 Vehicle Speed Sensor (VSS)
The Vehicle Speed Sensor is located on the left hand side of the frame on early models, and on 
the left hand side of the transfer case on later models.  It informs the ECM when vehicle speed 
is above or below 3 mph.  This information is used by the ECM to ensure that the idle air control 
valve (IACV) is moved to a position to prevent a stall when the vehicle comes to a stop.  DTC 68 
will be displayed if the MAF is greater than 3V at 2000-3000...