Does cycling glow plugs affect fast idle?

[Brutis]

I just got internet hooked up at the house yesterday, so I can finally spend some time on OB, so I'm asking a lot of questions. Hope I don't wear out my welcome.

I was wondering a couple of things. 1. is it harmful to the glow plugs to cycle them 3 or 4 times before I start my truck in the morning (they're Motorcraft BErus)? 2. Would cycling them 3 or 4 times throw off the fast idle solenoid when starting cold?

I ask because the fast idle has been off intermittently lately. When I use a jumper wire it works perfectly and set my idle at 850 (according to my dash tach). But when I start up it some times doesn't kick the idle up and just idles at 650 (again according to my dash tach).
The only thing I can think of is the cycling glow plugs. Reasonable or way off base?

Suggestions welcome.

 

[plywood]

Theoretically 3 or 4 cycles shouldn't hurt the GPs since the controller is designed to shut off before they get too hot, although it shouldn't really be needed. It knows their temp by indirectly measuring their electrical resistance.

Cycling GPs won't affect high idle, unless it is weakening the batteries enough that the high idle solenoid won't engage. Probably you just need to clean the connector at the water temp switch. It is a two prong water jacket switch on the front of the engine, you can locate it for sure by checking continuity between the connector on the IP and the connector at the switch.

 

[Brutis]

thanks. I'll try cleaning it tomorrow.