Whats happening is the glow plug control module is either seeing less than 32 amps pull on the left bank or that the difference between the left bank and right banks is more than 8.5 amps. there are connectors at the base of the valve cover toward the engine valley. they have seven pins in them. you want to test the outside two pins on the front and rear of the connector. they will have either yellow or brown wires. I would ohm out the glow plugs on the left bank first. they should not read more than 2 ohms. If one of them is, then either the under valve cover harness has high resistance or that glow plug has high resistance which either would need to be replaced. if the left banks is all ok then test the right bank but you want to see if any are shorted out. if any read less than about .5 ohms than either the uvch or the glow plug is shorted out. If you have any questions about how to test, let me know. sorry if this is confusing, i have a hard time putting actions to words. lol