Rooster, heres a little info to digest........... dont know if it will help you or not. From one of my manuals........
OUTPUT FUNCTIONS
Injection Pressure Regulator - Is a variable position valve that controls injection control pressure. The PCM uses many input variables to determine the desired injection control pressure.
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 Powertrain Control Module (PCM). On/off time is modulated from 0-50% dependent upon the desired injection control pressure.
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 PCM 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 PCM 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 PCM commands and measures two specific pre-programmed pressures. A fault code is set, if the pressures can not be maintained.
NOTE: THE ENGINE WILL NOT OPERATE WITH AN IPR CIRCUIT THAT IS NOT FUNCTIONING.
Connector Checks to Ground (B-) (Check with IPR Connector Disconnected and Ignition key off, all accessories off)
A to Grd.> 1000 ohmsResistance to chassis ground, if shorted to ground, #71 or #97.
B to Grd.> 1000 ohmsA short to ground will command full IPR pressure, code 1282 may be set.
Harness Resistance Checks(Check with breakout box installed on engine harness only)
#83 to #71 or #975 to 20 ohmsResistance through entire IPR circuit including regulator, check with regulator connector connected.
#83 to B< 5 ohmsResistance from 104 pin connector to regulator connector.
#71 or #91 to A< 5 ohmsResistance from power supply, #71 or #97 to regulator connector
IPR Voltage Checks(Check with regulator connector disconnected)
A to Grd.B+Batt. voltage from #71 or #97 check with key on (GP relay coil is supplied from PCM).
B to Grd.0 - .25vIf greater than .25 volts, signal wire is shorted to V Ref. or battery.
Diagnostic Trouble Code Description
1283=Output circuit check detected during Std. test, indicates high or low resistance in circuit,
1282=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 electronic fault.)
1211=(1) If set during normal engine operation indicates engine is operating in open loop control and ICP pressure is above or below desired pressure. (Refer to ICP control system diagnostics.)(2) If set during engine running test, indicates ICP system failed step test and could not maintain commanded pressure.
<< I love that one! 
