SIGNAL FUNCTIONS
The Injection Control Pressure (ICP) sensor is a variable
capacitance sensor that when supplied with a 5 volt reference signal
from the PCM 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 PCM 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.
FAULT DETECTION MANAGEMENT
If the PCM detects a malfunctioning ICP sensor, the CHECK ENGINE
lamp will illuminate. The PCM will go to open loop control of
injection control pressure. (Operate from an estimated ICP
pressure.)
At idle, the NGS tool will display a fixed PID value of 725
PSI for ICPA when a signal fault is present.
After removing connector always check for
damaged pins, corrosion, loose terminals, etc.
| Connector Checks to Ground (B-) |
| (Check with Sensor Connector Disconnected and
Ignition key off, all accessories off) |
| Test Points |
Spec. |
Comments |
| A to Grd. |
< 5 ohms |
Resistance to chassis ground check with key off, if > than 5
ohms harness is open. |
| B to Grd. |
> 1000 ohms |
Resistance less than 1000 ohms indicates a short to ground. |
| C to Grd. |
> 1000 ohms |
Resistance less than 1000 ohms indicates a short to ground. |
| Connector Voltage Checks |
| (Check with Sensor Connector Disconnected and
Ignition Key On) |
| Test Points |
Spec. |
Comments |
| A to Grd. |
0 - .25 volts |
If greater than .25 volts, signal wire is shorted to VRef or battery. |
| B to Grd. |
5 volts ± .5 |
V Ref. check with key ON, if voltage is not in spec.,
see V Ref circuit |
| C to Grd. |
0 - .25 volts |
If greater than .25 volts, signal wire is shorted to V Ref or battery. |
| Harness Resistance Checks |
| (Check with breakout box installed on engine
harness only) |
| Test Points |
Spec. |
Comments |
| #91 to A |
< 5 ohms |
Resistance from harness connector to 104 pin connector -
Signal ground |
| #90 to B |
< 5 ohms |
Resistance from harness connector to 104 pin connector - V
Ref |
| #87 to C |
< 5 ohms |
Resistance from harness connector to 104 pin connector - ICP
signal |
| Test Points |
Operational Voltage Checks |
| (+) #87 to (-) #91 |
(Check with breakout box installed in line with the PCM) |
| Voltage |
PSI |
MPA |
Comments |
| 1.0 v |
580 |
4 |
Minimum required at engine cranking speed 100 RPM |
| .88-1.19 v |
540-790 |
3.7-5.5 |
Normal warm idle voltage signal |
| 1.38-1.53 v |
960-1088 |
6.6-7.5 |
Normal high idle voltage signal |
| 3.22 v |
2520 |
17.4 |
Snap accel or full load pressure signal |
| Circuit Faults: |
Diagnostic Trouble Code Description |
| 1280 |
= |
Signal voltage was less than .039 volts for more than .2
seconds. |
| 1281 |
= |
Signal voltage was greater than 4.90 volts for more than .2
seconds. |
| 1212 |
= |
Signal above 1.625 volts with engine off. (1160 psi, 8
MPa) |
|
