I have a 997 john deere ZTR, and i am having a glow plug issue, the glow plugs come on for only like 6 seconds and it is not enough to get the engine started. I have been jumping with a wire from battery to glow plugs for about ten seconds, and it does the job every time. I have the technical manual for the machine but it does not mention anything about that timer. It says its is controlled by a thermistor, I am not sure where it is located. Does anybody have any ideas hot to fix this problem?