So on my way home early this week the CEL came on and the truck just died. After coasting to the side of the road it fired right back up. I drove home replaced the CPS with a new Motorcraft spare, cleaned the fuel bowl and put in a new filter, changed the oil, and ordered an AutoEnginuity scanner from Riffraff. The codes set were P0603 and P1212 (ICP pressure lower than desired) which I think is the most relevant one. Here are the results of my troubleshooting so far (trying to duplicate the Riffraff ICP/IPR troubleshooting example).
------------------------ICP-----ICP--------ICP
-----------------RPM--Volts---Pressure---DC%
KOEO.............0.0--4.73-----0.0-------14.84
@Idle............650--4.73-----724-------14.45
Above Idle....1580--4.73-----738-------12.50
Truck was not fully warmed up, just idled a little prior to test. These numbers don't mean much to me. The ICP volts look very suspicious... they are nothing like example AE screen shots on the Riffraff website. So any light you guys could shed on these numbers would be greatly appreciated. I'm really puzzled about the ICP voltage... is this the PCM taking over after it sensed an error condition? Next steps? Jim

1997 F250 XLT SC 4X4, PSD, E40D, 4.10LS, 144K

 

Disconnect the icp and see if it has oil in it. If so it's a good spot to start.

 

No oil coming out of the ICP... the wiring looks fine too.

 

Well now I have a new IPR, a very nicely rebuilt fuel bowl and regulator, plus new fuel hoses and clamps, but I still have the DTC P1212 and a new one... DTC 1280 (Injector Control Pressure Sensor Circuit Low). On a little closer inspection, now I'm thinking that the ICP volts is very close to the VREF volts I'm measuring with my multi-meter. I guess this could be caused by a direct short in the ICP wiring or maybe a bad ICP. Also maybe the PCM is just setting the ICP voltage because it's in 'fail safe' mode. I don't know how I can easily check out the wiring? I will probably just replace the ICP sensor, but I'm getting a little tired of just throwing parts at it. I guess I could take it to a 'real diesel mechanic', NOooooo! Jim

 

Installed a new OEM ICP sensor and that fixed my problem! CEL is gone and ICP volts at KOEO is .22, and .90 at idle.

 

Good deal!