glow plug goofiness

[Scott Nixon]

Sometimes plugs won't run (ie, yellow light doesn't come on). If I crank a second or two, they come on. Other day I had to crank a looooong time before they came on.

Is this a sign the relay/controller is going? Or is it a sensor that feeds into this module?

I know the plugs are good, after the yellow light cycles she fires right up.

Thanks,

Scott Nixon

[john8662]

Please update your signature to let us know what year model 6.2 you're working on.

If you turn the key and get no glow, but once the starter is cranking you get glow, that could sure be a sign of a failing controller. My guess would be that the contacts in the controller are failing, and the vibration of the engine cranking could cause them to make contact.

Other sources of the problem can be related to poor electrical connections to the controller or relay.

J

[Scott Nixon]

Sorry, should have specified.

It's an 1989 6.2 in a K3500.

Scott Nixon

[john8662]

With an '89 you have the electronic controller combined with relay in one unit (85+ unit). Anyways, most trucks had a glow plug inhibit switch, which connects to the passengers side head, on a rear block off plate. Check the connections on this unit as well.