Imposici´ on de restricciones

Glow plugs are fitted as standard on the C4.4 and C6.6.

When the ignition keyswitch is switched on, the engine ECU will monitor the coolant temperature and the inlet air temperature and decide whether the glow plugs are required. If so, the ECU will drive ECU connector pin 57 to ground, activating the glow plug relay.

The glow plug relay is supplied and fitted by the OEM. ET configuration for this feature is not necessary. This feature is permanently enabled.

7.1.1 Relay, Fuse, and Cable Gauge Specification

The relay coil should not draw more than 1A and should be fitted with either a resistor or diode to suppress flyback energy (back emf) when the relay is de-energized.

As the glow plugs may be activated during cranking, when the battery voltage may be low, it is recommended that relay is specified such that it will close at a voltage of 60 percent of nominal battery voltage or lower.

The relay contacts should be rated to withstand the current characteristics outlined in the table below. Note that for the purpose of relay specification, the glow plugs are a purely resistive load (no inductive element).

Although the glow plugs are normally operated only for a short time, in cold ambient conditions, best practice would be to size the cable to withstand the stabilized glowplug current permanently. This will allow for a relay that fails closed. For example a 4 Cylinder 12V application should have wire sized to carry 50A. Refer to the recommended cable sizes in the table below.

Engine: C4.4 C6.6

Supply Voltage: 12V 24V 12V 24V

Current — initial 82A 36A 122A 54A

Current after 4 seconds 64A 29A 97A 43A

Current after 8 seconds 50A 24A 74A 36A

Recommended fuse to

SAEJ1888 (slow blow) 50 30 80 40

Recommended min. cable gauge

— mm²(SAE J1128 GLX cable) 5 mm² 2 mm² 8 mm² 3 mm²

57 Start Aid Control

ECU J1

TO GLOW PLUGS

GLOW PLUG RELAY FUSE

Key Switched + Battery Supply

+ Battery

7.1.2 Wait-to-Start/Start Aid Active Lamps

On a cold start, when the ECU decides that it is necessary for the glowplugs to be activated prior to starting, a lamp output will indicate to the operator that he needs to “wait-to-start.” Note that it is possible that start aids will also be used either during cranking or when the engine has started. The wait-to-start lamp will not be active in these conditions. For further information refer to the Lamp Output section.

Note: The ECU will also transmit a parameter on the J1939 datalink indicating the status of the wait-to-start lamp (see section on J1939 support).

Start Aid Control Plugs will remain off after the

Pre-heat period until the

7.1.3 OEM/Operator Control or Override of the Glow Plugs

The ECU glow plug control strategy has been developed in a cold chamber to be suitable for the majority of applications.

There may be some applications that require a specially adapted strategy for control of the start aid. In such cases it will be necessary for the OEM or operator to control the start aid. Examples of applications that may require special starting strategies are:

• Engines in extremely cold climates that are fitted with block heaters.

• Engines that drive high loads during run-up; e.g., compressors.

Busbar connection point

An insulated M6 terminal post is provided for the machine harness connection to the busbar, which is located on the top right-hand side of the ECU bracket. A 5.5 to 6 mm diameter ring terminal is required to connect the machine harness; this should be insulated by a terminal insulator cap and be capable of handling an 80Amp current.

The existing terminal nut is used to locate both the engine-side and harness-side ring terminals to the post.

A 10 mm ring spanner is required to tighten the terminal nut to a torque of 6 Nm ± 2 Nm.

Customers who paint the engine are required to shield the terminal post prior to painting.

7.1.4 Ether Cold Start Systems

7.1.5 Water Jacket Heaters

When an engine water jacket heater is installed Caterpillar recommends the installation of an ambient air temperature sensor. When installed and configured, the ambient sensor measurement will be used by the ECU to ensure optimum engine starting and run-up.

Required Parts

Part Number Description Qty

106-0735 Temperature Sensor 1

155-2260 Connector Plug Kit 1

9X-3402 Socket 3

267-9572 Socket 3

The Caterpillar sensor 106-0735 is required for correct operation. The sensor should be located in a position that measures the application external ambient air temperature. A location should be chosen that avoids any radiated or conducted heat produced by the engine water jacket heater. The location and mounting design should protect the sensor from damage; the sensor probe is particularly vulnerable and should be guarded from possible impact damage.

NOTE: Do not splice the sensor signal wire for input to third party devices.

Recommended connector mounting for component with a pigtail harness:

• The connector interface should never be tied directly to a vibrating member.

• Pigtail wire lead should be tied down on only one side of the connector interface. Choose one of these two locations:

- midpoint on the sensor pigtail, OR

- 150 mm from the connector on the wire harness side

7.1.6 Ambient Temperature Sensor — ET Configurable Parameter

The “Ambient Air Temperature Sensor Installation Status” listed under start aid configurable parameters must be configured installed in Cat ET prior to using the sensor.

56 AMBIENT AIR TEMP SIG

33 ^{SENSOR RTN}

42 SENSOR SUPPLY +5 VDC

A B C +5 VDC

RTN SIGNAL

Temperature Sensor J1 ECU

45.9 mm 300 mm

8 Operator Displays