Section 31.1
Signal Functions
The Injection Control Pressure (ICP) sensor is a variable capacitance sensor that, when supplied with a 5 volt reference signal from the ECM, produces a linear analog voltage signal that indicates pressure.
The ICP sensor’s primary function is to provide a feedback signal to indicate injection control pressure to enable the ECM to command the correct injector timing and pulse width, and the correct injection control pressure for proper fuel delivery at all speed and load conditions. For ICP sensor function diagram, see Figure
“Injection Control Pressure Sensor Function Diagram”
.
Figure 1. Injection Control Pressure Sensor Function Diagram
Section 31.1.1
Fault Detection/Management
If the ECM detects a malfunctioning ICP sensor or a problem in the ICP sensor circuit, the WARN lamp will illuminate. The ECM will go to open loop control of injection control pressure. (Operate from an estimated ICP pressure.) For Injection Control Pressure Sensor (ICP), see Figure
“Injection Control Pressure Sensor”
.
Figure 2. Injection Control Pressure Sensor
Connector voltage checks are listed in Table
“Connector Voltage Checks”
. Checks are made with the sensor connector disconnected and the ignition key ON.
|
Test Points |
Spec |
Comments |
|
A to Grd |
0 volts |
Signal ground; no voltage expected. |
|
B to Grd |
5 volts ± .5 |
VREF check with key ON; if voltage not in spec, see VREF circuit. |
|
C to Grd |
< 0.25 volts |
If greater than 0.25 volts, signal ground wire is shorted to VREF or battery. |
Connector checks to chassis ground are listed in Table
“Connector Checks to Chassis Ground”
. Checks are made with the sensor connector disconnected, the positive battery cable disconnected, and the ignition key OFF.
|
Test Points |
Spec |
Comments |
|
A to Grd |
< 5 Ω |
Resistance to chassis ground, check with key OFF; if > 5 Ω, the harness is open. |
|
B to Grd |
> 1,000 Ω |
Resistance less than 1,000 Ω indicates a short to ground. |
|
C to Grd |
> 1,000 Ω |
Resistance less than 1,000 Ω indicates a short to ground. |
Harness resistance checks are listed in Table
“Harness Resistance Checks”
. Checks are made with the breakout box installed on the engine harness only.
|
Test Points |
Spec |
Comments |
|
#19 to A |
< 5 Ω |
Resistance from sensor connector to 60-pin connector – Signal ground. |
|
#40 to B |
< 5 Ω |
Resistance from sensor connector to 60-pin connector – VREF. |
|
#16 to C |
< 5 Ω |
Resistance from sensor connector to 60-pin connector – ICP signal. |
Operational signal checks are listed in Table
“Operational Voltage Checks”
. Checks are made with the breakout box installed on the ECM and engine (Gray) harness.
|
Test Points (+) #16 to (-) #19 |
Operational Voltage Checks (Check with breakout box installed on ECM and Engine (Gray) Harness |
||
|
Voltage |
PSI |
MPA |
Comments |
|
.15 – .30v |
0 |
0 |
Atmospheric pressure with key ON, engine OFF. (Altitude dependent) |
|
1.0v |
580 |
4 |
Minimum required at engine cranking speed 150 r/min. |
|
.74 – .81v |
425 – 475 |
2.9 – 3.2 |
Normal warm idle voltage signal (Check performance specs.) |
|
1.34 – 1.68v |
865 – 1157 |
6.0 – 8.0 |
Normal high idle voltage signal (Check performance specs.) |
|
3.334v |
2550 |
17.6 |
Snap accel or full load pressure signal. |
Fault code descriptions are listed in Table
“Fault Code Descriptions”
.
|
Circuit Faults |
Descriptions |
|
124 |
Signal voltage was less than 0.039 volts for more than 1.0 seconds. |
|
125 |
Signal voltage was greater than 4.90 volts for more than 1.0 seconds. |
|
332 |
Signal above 1.625 volts with engine off. (1160 psi, 8 MPa). |
Section 31.1.2
Function
The engine control system includes an Injection Control Pressure (ICP) sensor. The ECM measures the signal from the ICP sensor to determine the injection control pressure as the engine is running to modulate the ICP regulator. This is a closed loop function that means the ECM continuously monitors and adjusts for ideal ICP determined by operating conditions such as load, speed and temperature.
The ECM monitors the ICP signal to determine if the performance of the hydraulic system is satisfactory. During engine operation, if the ECM recognizes that the pressure reading is lower or higher than the value that was commanded, the ECM will set a fault code. This strategy is also used during the On Demand tests, commanded by the EST and referred to as the Engine Running tests.
Section 31.1.3
Operation
The ICP sensor is a variable capacitance sensor that is supplied with a 5 volt reference voltage at terminal B by the ECM from terminal 40. The ICP sensor is also supplied with a return circuit (ground) at terminal A from ECM terminal 19. The ICP sensor sends a signal from terminal C of the sensor to ECM terminal 16.
The ICP signal voltage increases or decreases equally in proportion to an increase or decrease in injection control pressure.
Section 31.1.4
ECM Diagnostics
The ECM continuously monitors the signal of the ICP sensor to determine if the signal is within an expected range. If the signal voltage is higher or lower than expected, the ECM will set a fault code. The ECM will then ignore the ICP sensor signal and will use a preset value determined by engine operating conditions. If the ignition key is shut off, the code will become an inactive code.
ICP faults can be retrieved using the EST or by reading the flash codes from the warning light using the STI diagnostic switch located on the vehicle dash.
If the ignition key is shut off, the code will become an inactive code. ICP codes will cause the Engine Warning light to illuminate.
Section 31.1.5
Flash Codes
Flash codes that could display when troubleshooting the ICP include:
Section 31.1.5.1
Flash Code 124
ATA Code PID 164 FMI 4
ICP signal out of range LOW.
An out of range low code 124 will be set by the ECM if the signal voltage is less than 0.039 volts for more than 1.0 seconds.
Flash Code 124 may be set due to an open or short to ground on the signal circuit, a defective sensor, or an open VREF circuit at the sensor.
Section 31.1.5.2
Flash Code 125
ATA Code PID 164 FMI 3
ICP signal out of range HIGH.
An out of range high code 125 will be set by the ECM if the signal voltage is greater than 4.9 volts for more than 1.0 seconds.
Flash Code 125 may be set by an open return circuit, short to a voltage source on the ICP signal circuit or a defective sensor.
Section 31.1.5.3
Flash Code 332
ATA Code PID 164 FMI 13
ICP pressure above specification with engine off.
Flash Code 332 will be set by the ECM if the signal from the ICP sensor is higher than expected with the engine not running. If the ECM detects this fault, the ECM will ignore the ICP signal and will operate the IPR with fixed values determined from engine operating conditions.
Flash Code 332 may be caused by a defective sensor or a biased circuit.
| Series 40E Troubleshooting Manual – 6SE241 |
| Generated on 10-13-2008 |
