Caterpillar 277C cold start relay not getting enough voltage to switch

[samhaley]

I have an 09 caterpillar 277c serial JWF1539 with starting issues. The machine cranks but it does not start without having some starting fluid spayed into the air intake, after that it runs great with no noticeable issues. At first it would smoke mid/high throttle but I adjusted the fuel injection pump housing and it fixed the issue. Guy I bought it from said the starting issues began when it was parked inclined on a hill and the lines ran out of gas/had air in them. He replaced the fuel injection pump, fuel filter and glow plugs but Upon some troubleshooting I noticed that the glow plugs weren't getting any power, I took out the glow plug relay located inside the engine compartment bolted onto a bar and sure enough its not switching. I probed the input voltage and get 10.1 Volts which was strange so i bench tested the relay with a power supply set at 10.1 Volts and its enough to switch it on. So I then did a current test and on the bench it draws 100 mA to switch but jumped to the plug its not drawing any current. Even though 10V is enough to switch there is an issue since an identical starter relay on the other side of the engine gets the full 12V to switch.

This same harness has leads going to the fuel pump so I suspect it might also not be switching the cold start solenoid which might be causing my starting issue. So far I suspect that it is either the wires, the connector socket or some regulator inside the ECM. Am I missing anything else? Also to service these components it would be much easier to remove the hydralic tank bolted onto the cabin. Are there any caveats to be aware of if I decide to remove this tank to test the wiring? Thanks