exactly. I think I read a post somewhere that a guy was told by cummins that they would be happy to do injector work for him, but that was it, they couldnt do any ECM work because his was an 03.

 

When you first key it on and the grid heater light comes on does the battery voltage pull down to around 10 volts then back up to 12 after it cycles. If so I wouldn't think the grid heater is the problem.

If it doesn't pull the voltage down then check your voltage going to your grid heater relays. Disconnect one side of the grid heater and ohm across the heater element, it should be pretty low resistance. If it is open then the element has failed.

You should have 12 volts on one side of the large terminals of the relay at all times. If you don't have 12 volts to the large studs of the relay then check the fuse.

You should also have 12 volts on one of the small terminals when calling for the block heaters to come on. If not it could be a control issue. If so then lift a wire off one end of the coil and ohm across the coil.

Do some simple checks before you end up with a set of injectors and the same problem.