Would it be harmful to disconnect a fuse or relay or whatever it takes
to disable the "wait to start" grid heaters? I dont normally wait for the
light to go out anyway since it usually doesn't get below freezing here.
Thanks in advance for any info or suggestions.

 

If it ain't doing any harm to you're trucks batteries then I would leave it be. The grids aren't activated above 59º anyway.

Temps 59ºF and above - grids aren't activated. The WTS light stays lit for only 2 seconds.
59º - 32ºF, Grids are activated for 10 seconds prior to starting and the WTS light stays lit for 10 seconds. The ECM also cycles the grids to aid in warm-up until ~23 MPH or coolant temps reach 140º
32ºF and below, grids are activated for 30 seconds and the WTS light stays lit for 30 seconds as well. Post start up grid cycling occurs as described above.

Hope this helps you.

 

Thanks for comeback jrs, however I would like to disconnect as tired of the
diming lights,etc. Do you know what to disconnect or does anyone else have
another idea ?? Thanks again

 

The dimming lights are normal, just the nature of the beast. There are two grid heaters (one on top of the other), each draw around 90 amps. That is one heckuva load on your electrical system but it is capable of handling it.

I personally don't reccomend disconnecting it.

 

On my 1999, modified my grid heaters to cycle only once at initial startup before cranking the engine. Once the engine starts and the oil pressure is rising, the grid heaters will not cycle at all. Used an oil pressure switch (Normally Closed, opens with pressure) and installed on top of the oil filter housing in one of the oil ports. Connected a wire from the switch to the grounding wires on the control circuit on the Grid Heater relays, not the grid heater themselves (disconnected original ground wires on relay). Once the oil pressure rises, the grounds to engage the relays are open so the grid heaters never operate after the initial first heater cycle.

Be warned, this does set an internal error code (e.g., Grid Heaters Inop) but will not illuminate the Check Engine light. Have used this for roughly 3 years and have had no problems. Usually use this configuration during late Spring, Summer, and Fall. Just reconnect the original two ground plugs during winter so grid heaters cycle normally. Thank another individual about 4 years ago for designing this (do not know his name). If any questions or interested in parts, PM me.

Cheers!