Heater grid problems

[RMcGuffey]

I have a 1990 truck I'm having problems with. On cold

mornings when I start it, the WTS light comes on and the

heaters cycle like they're supposed to, but after it starts,

they won't cycle anymore, regardless of the temperature.

It also seems to be getting harder to start. Any ideas would

be helpful. Thanks.

 

[bgilbert]

RM, now when you say after it starts it won't cycle anymore, is this because you don't hear the relays clicking or the wait to start light goes out? On my 89 the WTS light will not come on til below 15F, but it looks as though my grid heaters operate above 15F in a post heat or post start mode, indicated at night by my headlights, dash dome lights etc dimming as i go down the road, until the intake temp reaches a certain temp. This would indicate to you if your lights dimmed, ammeter or voltmeter fluctuated after starting, that your grid heaters are cycling normal after starting. Bill