Pinpoint Test R: Injection Pressure Regulator (IPR): Introduction: Detection/Management
An open or short to ground in the IPR control circuit can be detected by an on-demand output circuit check carried out during the key on engine off (KOEO) self-test. An injection control pressure step test, in which the PCM commands and then measures specific preprogrammed pressures is carried out during the key on engine running (KOER) self-test.
The PCM is also capable of detecting whether the desired injection control pressure is equal to measured injection control pressure while the engine is running. If the measured injection control pressure does not reasonably compare to the desired injection control pressure, the PCM ignores the measured ICP sensor signal and attempts to control the engine with the desired value. (If the problem was in the ICP sensor circuit this strategy causes minimal performance deterioration. If the problem is in the IPR control circuit, engine performance may be unsatisfactory).