The Injector Pressure Regulator (IPR) is a variable position valve that controls injection control pressure. The ECM uses many input variables to determine the desired injection control pressure. For the IPR function diagram, see Figure
“Injection Pressure Regulator Function Diagram”
.
Figure 1. Injection Pressure Regulator Function Diagram
Section 33.1.1
Output Functions
Battery voltage is supplied to the IPR when the ignition key is in the ON position. Valve position is controlled by switching the output signal circuit to ground inside the ECM. ON and OFF time is modulated from 0 — 60% dependent upon the desired injection control pressure.
Section 33.1.2
Fault Detection / Management
An open or a short to ground control circuit can be detected by an on demand output circuit check performed during the engine off test.
The ECM is capable of detecting, while the engine is running, if desired injection control pressure is equal to measured injection control pressure. If the measured injection control pressure does not reasonably compare to the desired injection control pressure, the ECM ignores the measured ICP signal and attempts to control the engine with the desired value. (If the problem was in the sensor circuit, this strategy causes little performance deterioration. If the problem is in the control circuit, engine performance will probably still be unsatisfactory.
A faulty IPR or problem with the high pressure oil system can be detected by the engine running test during the injection control pressure step test. During this test, the ECM commands and measures two specific pre-programmed pressures. A fault code is set if the pressures cannot be maintained.
For the IPR function diagram, see Figure
“Injection Pressure Regulator”
.
Figure 2. Injection Pressure Regulator
Note: The engine will not operate with an IPR circuit that is not functioning.
The IPR voltage checks are listed in Table
“IPR Voltage Check”
. Checks are performed with the regulator connector disconnected and the ignition key ON.
| Test Points | Spec | Comments |
| A to Grd | B+ | IPR power voltage from the ECM. |
| B to Grd | 0 – 0.25v | If greater than 0.25 volts, the signal wire is shorted to VREF or battery. |
The connector checks to ground are listed in Table
“Connector Checks to Ground (B+)”
. Checks are performed with the IPR connector disconnected and the ignition key OFF; the positive battery cable disconnected.
| Test Points | Spec | Comments |
| A to Grd | > 1,000 Ω | Resistance to chassis ground. If less than 1,000 Ω, check for short to ground in circuit.
Remove fuse F5 in fuse box prior to measuring resistance. |
| B to Grd | > 1,000 Ω |
The harness resistance checks are listed in Table
“Harness Resistance Checks”
. Checks are performed with the breakout box installed on the engine harness only.
| Test Points | Spec | Comments |
| #17 to #37 | 5 to 20 Ω | Resistance through entire IPR circuit including regulator; check with regulator connector connected to IPR. |
| #17 to A | < 5 Ω | |
| 37 to B | < 5 Ω | Resistance from 60-pin connector to regulator connector. |
Fault code descriptions are listed in Table
“Fault Code Descriptions”
.
| Flash Code | Description |
| 241 | Output circuit check detected during Standard Test, indicates high or low resistance in circuit. |
| 331 | ICP pressure was greater than 3675 psi (25 MPA) for 1.5 seconds. (Possible grounded IPR control circuit.) Refer to injection control pressure diagnostics if not an electronic fault. |
Section 33.1.3
Function
The engine control system includes an IPR valve that controls oil pressure in the high pressure injection control system that actuates the injectors.
The IPR valve consists of a solenoid, poppet and spool valve assembly and is mounted in the high pressure oil pump. The ECM regulates injection control pressure by controlling the duty cycle or ON/OFF time of the injection control pressure solenoid. This increase or decrease of ON/OFF time positions a poppet valve and spool valve internal to the IPR, which in turn, either maintains pressure in the injection control pressure system or vents pressure to the oil sump via the front cover.
For a more complete description of the IPR operation and function, refer to “3.1 Injection Control Pressure System Operation”
.
Section 33.1.4
Operation
The IPR valve is supplied with voltage at terminal A of the IPR connector when the ignition key is turned on through the ECM. Control of the injection control system is accomplished by the ECM grounding the IPR circuit from terminal B of the IPR valve through pin No. 37 of the ECM. Precise control is accomplished by varying the pulse width or percentage of ON/OFF time of the IPR solenoid. The frequency of the pulse width to the IPR is 400 Hz. Normal ON/OFF times vary from 8% to 60%.
A high duty cycle indicates a high amount of injection control pressure being commanded; a low duty cycle is an indication of less pressure being commanded.
Section 33.1.5
ECM Diagnostics
The ECM monitors the injection control pressure while the engine is in operation. If the actual pressure is greater or less than the desired pressure, the ECM will set a fault code. When this occurs, the ECM will ignore the ICP sensor and control the engine using pre-programmed values for the IPR.
The EST is used to perform the Engine Running Standard Test that enables the ECM to vary the command signal to the IPR and monitor the performance of the Injection Control Pressure System. If the system does not respond within the specified parameters, the ECM will set a fault code.
Fault codes can be retrieved using the EST or the Self Test Input diagnostic switch located on the vehicle dash. If the ignition key is shut off, the code will be stored as an inactive code.
Section 33.1.6
Flash Codes
The following flash codes could be set while troubleshooting the IPR.
Section 33.1.6.1
Flash Code 241
ATA Code SID 42 FMI 11
Injection control pressure regulator OCC Self Test failed.
Flash Code 241 is set only during the Engine OFF Standard Output Circuit Check. This test indicates the ECM has performed an output circuit test, measured the voltage drop across the IPR circuit, and determined it is below or above specification.
If this fault is present, the engine will not run. The ECM will not illuminate the engine warning light if this code is active. However, this code will be transmitted at the completion of the Output Circuit Check, using the STI switch or the EST.
Section 33.1.6.2
Flash Code 331
ATA Code PID 164 FMI 0
Injection control pressure above system working range.
Flash Code 331 indicates the ECM has detected injection control pressure greater than 3675 psi (25 MPA) which is greater than the maximum allowable working pressure.
When this code is active, the ECM will illuminate the engine warning light.
Possible causes for this condition include incorrect ICP signal due to faulty circuits or sensor, grounded IPR signal circuit, a malfunction in the injection control pressure system, or a sticking or blocked IPR valve.
| Series 40E Troubleshooting Manual – 6SE241 |
| Generated on 10-13-2008 |