RangeRover Sport / L494 2017 GLOW PLUG SYSTEM MANUAL 

You are here:
Estimated reading time: 4 min

E190632

 








ITEM DESCRIPTION
1 Glow plug control module
2 Glow plug warning indicator
3 Glow plugs (6 off)
4 Powertrain Control Module (PCM)

The glow plug system includes a glow plug installed in the inlet side of each cylinder and a glow plug control module. The glow plugs heat the combustion chambers before and during cranking, to aid cold starting, and after the engine starts to reduce emissions and engine noise when idling with a cold engine.

The glow plugs are connected for each bank by a common harness which is connected into the main engine harness. The harness for each bank connects into a connector block which attaches to each of the glow plugs for that bank. The glow plugs are connected directly to the glow plug control module, which is controlled by glow plug software contained within the Powertrain Control Module (PCM).

GLOW PLUG

The ceramic sheathed element glow plugs are made from a heat-resistant, electrically conductive ceramic material. The ceramic sheathed-element glow plugs outer layer is heated directly and is self regulating. The self-regulation allows the resistance of the sheathed element to automatically increase as the heat increases preventing the glow plug from overheating. In addition, during the heating process and under the control of the glow plug relay, the glow plugs can be operated above their nominal voltages. This permits heat-up speeds of 1000°C (1832ºF) <2 seconds. The sheathed-element glow plugs reach a maximum glow temperature of 1300°C (2372ºF) and can hold a temperature of 1250°C (2282ºF) for several minutes after the first-start glow or at intervening times.

Each cylinder bank has a separate harness connecting the three glow plugs. The harness connects into the engine wiring harness and each harness has a connector block which attaches to each of the glow plugs for that bank.

The glow plug control module receives a permanent primary battery supply via fuses in the Battery Junction Box (BJB) and the Auxiliary Junction Box (AJB) The glow plug control module also receives a switched power supply from the PCM relay in the Engine Junction Box (EJB). Operation of the glow plug control module is controlled by the PCM, which also controls the illumination of the glow plug warning indicator in the instrument Cluster (IC).

The system has been designed as a low-voltage glow system. At 7 volts, the nominal voltage of the sheathed-element glow plugs is significantly lower than the 12 volts of the main electrical circuit. The electronic glow plug control module matches the voltage to the sheathed-element glow plugs and controls their glow temperature precisely to the specific requirements of the engine. This produces the optimum glow temperature even when the main circuit voltage is interrupted during engine starting. The lower power consumption of the ceramic glow plugs and their time-staggered activation reduce to a minimum the peak load on the main circuit during the cold start and immediate post-start periods.

In the event of glow plug failure, the engine may be difficult to start and excessive smoke emissions may be observed after starting.

There are three phases of glow plug heating:

  • Pre heating
  • Crank heating
  • Post heating.

The Powertrain Control Module (PCM) determines the heating times from the Engine Coolant Temperature (ECT) sensor. The lower the ECT, the longer the heating times. If the ECT sensor fails, the PCM will use a predefined temperature as a default value.

The PCM monitors the feedback from the glow plug control module. If a fault is detected, the PCM stores a related fault code and permanently illuminates the glow plug warning indicator while the ignition is on.

PRE-HEATING

Pre-heat is the length of time the glow plugs operate prior to engine cranking. The PCM controls the pre-heat time based on ECT sensor output and Barometric pressure (BARO). The pre-heat duration is extended if the coolant temperature is low and/or the barometric pressure is low (at altitude).

When the stop/start switch is pressed while the brake pedal is being pressed, the PCM calculates any required glow plug heating times and, if heating is required, signals the glow plug control module, which supplies power to the glow plugs. When pre heating is required the PCM also sends a message to the Instrument Cluster (IC), on the FlexRay systems bus to the Body Control Module/Gateway Module (BCM/GWM). The BCM/GWM then forwards the message to the IC on the high speed Controller Area Network (CAN) chassis system bus to request illumination of the glow plug warning indicator. The glow plug warning indicator remains illuminated for the duration of the pre heating phase, until the PCM cranks the engine. If required, the glow plug control module supplies power to the glow plugs during cranking and for the duration of any post heating phase.

The Barometric pressure also has an influence on activation and deactivation of the glow plugs in the event of large altitude differences.

CRANK HEATING

Crank heating is carried out at every start where the coolant temperature is below the predefined threshold of 20°C (68ºF). Crank heating begins if the engine speed exceeds 80 rev/min for longer than 50 milliseconds, or the starter is active for longer than 4 seconds. If the ECT sensor is defective, a default temperature of 0°C (32ºF) is used.

POST HEATING

Post heat is the length of time the glow plugs operate after the engine starts. The PCM controls the post heating time based on ECT sensor output. The post heat phase reduces engine noise, improves idle quality and reduces hydrocarbon emissions.

Preheating is followed by the post heating phase once the engine has started. The post heating phase depends upon how the vehicle is driven.

In addition to ECT, barometric pressure and engine speed, the injected fuel quantity is significant in this context. For example, if the injected fuel quantity is less than 70 mg per piston stroke and the coolant temperature is below -20°C (-4ºF), post heating is performed.

E190633

 

A = HARDWIRED; AM = HIGH SPEED CAN CHASSIS SYSTEMS BUS; AX = FLEXRAY SYSTEMS BUS
















ITEM DESCRIPTION
1 Powertrain Control Module (PCM)
2 Body Control Module/Gateway Module (BCM/GWM)
3 Instrument Cluster (IC)
4 Glow plug (6 off)
5 Glow plug control module
6 Fuse – permanent power supply from Auxiliary Junction Box (AJB)
7 Fuse – power supply from Engine Junction Box (EJB)
8 PCM Relay – located in EJB
9 Ground
10 Fuse – power supply from Engine Junction Box (EJB)
11 PCM Relay – located in EJB
12 Fuse – power supply from Auxiliary Junction Box (AJB)

 

Was this article helpful?
Dislike 0
Views: 4
Previous: RangeRover Sport / L494 2017 AUTOMATIC TRANSMISSION/TRANSAXLE 
Next: RangeRover Sport / L494 2017 ENGINE EMISSION CONTROL MANUAL