[Nitrous340]

Have you tried pulling the grid heater relay?

 

[Sandman76]

Grid heaters controlled by the ECM by looking at your incoming air temp.

 

[johnyb59]

:agree2: Your IAT sensor maybe bad.

 

[joverfelt]

i looked all over for a grid heater relay......is it called something else? keep in mind im new to diesels all together, sorry if i sound stupid.....i am. i do know if i unhook the alternator, it runs perfect...so i know its somethin pullin on the charging system...

 

[johnyb59]

Since your truck is an 02 do the key trick. On off on off then leave it on. If you have any codes they will read in your odometer. If you have any post them back up here. This may help us figure out what your problem is.:thumbsup:

 

[joverfelt]

no codes...i do that every morning, hoping something will show up....i made one trip on purpose last nite to see if the coolant sensor by the thermostat was working, and to make sure a code would show up.....it did....cleared it with my scanner, and no codes now.

 

[Nitrous340]

So you unhooked the coolant sensor to get the code? The heater relay should be in a good size fuse panel that under a plastic cover. Its located inbetween the batt and mastercylinder right next to the fender.

 

[joverfelt]

yessir, unhooked coolant sensor to make it throw a code.....i know where yer talkin bout....i will look again, swear i never saw a grid heater relay.....prolly overlooked it tho....if i pull it and the truck runs right, will it likely be the iat sensor? or that relay? guess i can check the relay...

 

[Sandman76]

The grid heater relays (two of them) are under the driver's side battery tray mounted on the fender NOT in a box. Trace the grid heater wire back. Only way to disconnect the relays for the grid heater is to disconnect it from the battery terminal or from the grid heater terminals (in the last case make sure to insulate the end with electrical tape so it doesn't short out under the hood). A lot of the time the grid heater relays will arc closed (even temporarily) and cause a loss in voltage in the system. The grid heaters consume aprox 90-100 amps each and your alternator is only capable of MAX 130 amps and even less at idle. I replaced my grid heater relays last fall, they come as a pair on a common bracket so only order one from Dodge if you are ordering. I also found them at a well stocked local parts store, but Dodge was $50 cheaper at $104 for the pair.

 

[Blue2003]

The grid heater relays (two of them) are under the driver's side battery tray mounted on the fender NOT in a box. Trace the grid heater wire back. Only way to disconnect the relays for the grid heater is to disconnect it from the battery terminal or from the grid heater terminals (in the last case make sure to insulate the end with electrical tape so it doesn't short out under the hood). A lot of the time the grid heater relays will arc closed (even temporarily) and cause a loss in voltage in the system. The grid heaters consume aprox 90-100 amps each and your alternator is only capable of MAX 130 amps and even less at idle. I replaced my grid heater relays last fall, they come as a pair on a common bracket so only order one from Dodge if you are ordering. I also found them at a well stocked local parts store, but Dodge was $50 cheaper at $104 for the pair.

:agree2: that is where they are located.