Update???

 

no I have been busy my grandfather passed away and his funeral was today. I planning on getting up in the next few minutes to go give it a good cleaning.

 

My condolences Bia...

 

one thing you could try is since it never gets cold in TX you could unplug the 2 control wires that go to the solonoids. you should have 2 wires per solonoid that is bolted on and then 1 that is in a 90* connector that slips on (like a starter solonoid on a Ford gasser), this is the wire to dissconnect. that would comepletely take the grid heater out of the conclusion unless a solonoid is bad and still making it dim. doing that you should be able to reference ground to the battery and probe the solonoids 2 remaining wires. one side of the solonoid should have 12v and the other side should read 0v with that control wire removed. do this on both solonoids. if this keeps the lights from dimming then that narrows it to the grid heater relays, IAT, or any other electrical problem.

Doc..... i doubt that it would be the solonoid being bad because if it was it would drain the battery in a heartbeat or melt the wire insulation when the truck isn't being driven, i'd bet on the relays myself having the control circuit shorted or a sticky contact inside staying latched..... i could be wrong but that's what i thought.. but then again it won't come on unless the air temp is cold enough.......hmmmmm what part in the circuit is controlled by the speed? this to me almost seems to be the problem as it should quit cycling no matter how cold the motor is once you reach 15-25 MPH.....

 

It seems there may be some confusion between the 12V and 24V trucks. I believe the grids work somewhat differently.

 

Bia, if the Iat doesn't work you can live without the grid heater here, I know for us its been cold the past few days but our trucks can take it alot better than we can, I unhooked mine to see how it would do, before I buy the spacer plate, and its been firing right up since this strong front came through.

 

doc i added some info.... i forgot to refresh the page before i edited..... how's the difference on the 12 and 24v trucks? pics would be nice if that's what you are talking about since you have one of each that might help..... also are the heaters controlled by the comp on a 24v?