The ECM controls the injection control pressure by operating the injection control pressure regulator (IPR). See Figure
“Injection Control System”
. The result of this control is continuously monitored by the ECM using the injection control pressure sensor (ICP). The pressure signal obtained from the ICP allows the ECM to know the actual injection control pressure at all times of engine operation or even during cranking mode. This operation is known as closed loop. See Figure
“Closed Loop Operation”
.
Figure 1. Injection Control System
Diagnostic codes can be set by the ECM if the ICP electrical signal is out of range or if the ICP signal received corresponds to an out of range value for the injection control pressure at a given operating condition.
Should these occur, the ECM will ignore the ICP signal and control the IPR valve operation from pre-programmed default values. This condition is known as open loop.
Figure 2. Closed Loop Operation
| Series 40E Troubleshooting Manual – 6SE241 |
| Generated on 10-13-2008 |