Installation Manual

Electrical & Electronic Application And Installation Manual
Production Release Version 1.0
Page 162
12.1.2 Glow Plug System Configuration
If operation of engine glow plugs is not required, then no control hardware is
required to be installed. Please note that whilst both Glow plugs and ether
can be fitted to the same engine, the start aids cannot be operated at the
same time for safety reasons. Please do not under any circumstances bypass
the ECM control of either start aid.
12.1.3 Glow Plug System Installation
Figure 12.3 Glow Plug Relay electrical Connection
The relay coil must not draw more than 2A and should be fitted with either a
resistor or diode to suppress flyback energy (back emf).
As the glow plugs may be active during cranking, when the battery voltage
may be low, it is recommended that the relay be specified such that it will
close at a voltage equivalent to 60% 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 for a short time only, in cold
ambient conditions, best practice would be to size the cable to withstand the
stabilized glow plug current permanently. This will allow for a relay that fails
closed. For example a 4 cylinder 12V application should have a wire size
capable of carrying 50A. Refer to the recommended cable sizes in the table
below.
Engine:
1204F
1206F
Supply Voltage:
12V
24V
12V
24V
Current
-
Initial
82A 36A 122A 54A
Current after 4 sec
64A 29A 97A 43A
Current after 8 sec
50A 24A 74A 36A
Recommended Fuse
To SAEJ1888 ( slow blow)
50A 30A 80A 40A
Recommended min cable
gauge - mm
2
(SAE J1128
GXL cable)
5mm² 2mm² 8mm² 3mm²
Table 12.1 Glow Plug Requirements
To ensure the correct operation of the cold start strategy it is recommended
that customer selected relay meets the specification shown below.
8
GLOW PLUG START AID RELAY
TO GLOW
PLUGS
GLOW PLUG
RELAY
49
DIGITAL SENSOR RETURN
FUSE
Battery +