I have a Cat PC 4000 that ran ruff when it was shut off it would not restart. ( cranks but will not start) it is giving a E-28 code camshaft position sensor. I have competed the following tests.

1. Checked and replaced Plugs
2. verified Power and ground at both cam and crank sensors
3. Changed both Cam and crank sensors
4. Put in a known good ECM
5. Cleared codes and attempted to start between steps
6. back-probed sensors for signal voltage during cranking. voltage found to be high on both sensors. 2-7v
Im hesitant to spend for a new wiring harness and was hoping someone had a schematic or procedure for locating the wires and checking voltage at the ECU?
any help or advise is much appreciated!
Nathan