SES with Code 1275 questions and How do you open the IDM?

SES with Code 1275 questions and How do you open the IDM?

Well the code scanner confirmed what I determined with the "finger test", my problem cylinder is #5. A little back ground, the truck went from running great to running really bad and setting the SES light in a matter of less than 2 minutes I would guess.

From the PCED manual Code 1275 indicates a low side to high side open in the circuit between the IDM and the injector. This is the only code I have. KOER, have no running codes and it did the self test thing OK.

To date I have visually inspected the UVC injector harness on right side, ohmed through the connector at the VC and ohmed through from the IDM connector, wiggled stuff and can find no "open" in #5 (or 1,3,7 for that matter). Inspected IDM connector as well.Checked for the rubbing on valve cover thing(although that should give the short to ground code, not 1275). PCED says at this point replace IDM.

Any suggestions on what else to check before hunting down an IDM?
Anyone have a harness check good with ohm meter, but replacing harness fixed the problem?
In another thread it was posted a bad injector won't set an SES light, Is this true?

and last

How do you open the IDM? I cut the sealant bead and pryed on it a little but didn't want to mess it up. Is there a trick to it? Want to check for water/internal corrosion but can't get in there.

Thanks!

ddog