Hello I have 3 ground wires that are mounted to the firewall. 2 of them are connected somewhere else but one is not and I have no clue where it goes. I had to change the heater core this weekend and I do not remember taking a ground off any of the few bolts that holds the unit on inside the dash. If someone could tell me where all 3 are suppose to be connected that would be great. I have a 1999 Dodge Ram 1500 4x4 5.9l. Thanks

 

That one goes to the back of the head, I do believe.

 

I wonder how long it is been off? I've had the heads replaced but that's been about 8 years ago. Wouldn't something not work right or throw a code. Haven't noticed anything unusual happening from it not being connected to something.

 

Maybe, maybe not.... There is usually more than one ground path from engine to body/frame.....

 

Thanks for the input

 

AFAIK---From those three, One goes As mentioned, to the Backside of the [L] Head (bolt faces FW),
the Two on the FW itself lead to the A/T "Brain"(near the Hvac Condenser) and Main ECU (closer to the Batt)
I may be off a bit, but the Head Mounted on on mine broke off So to quiet concerns of Arcing it or Blowing vitals I snipped it off. As mentioned there are So many Ground Paths between the battery, chassis,Body, and engine Block it'self BESIDES one carried throughout the harnesses One ground cut out is equal to a single grain of sand at the beach.

 

That's not quite true. The engine to firewall ground is important for a number of actual electrical reasons that can be mathed out if you take the time.

Operate on the assumption that Dodge built these trucks as cheaply as possible, cutting corners every chance they could, from thin and crack prone heads to so-so transmissions and axles.
If the ground strap is there, it's not something that's redundant. It's necessary.

 

Here is an interesting tidbit concerning grounds that people think they don't need. It's called Electrolysis. I've seen this several times over the years. Especially those spots where that head ground gets left off. Sometimes this happens when the ground is insufficient as well.


One that comes to mind is the older 3.3 and 3.8 in the minivans where the rocker shaft towers would break on one end of the rear head.


Here is some copy/paste from a site that sells Anode Radiator Caps.


Explanation of Electrolysis

One failure mode associated with dirty coolant is known as electrolysis. Electrolysis occurs when stray negatively charged ions (electrical current) routes itself through the engine coolant. The electricity is attempting to find the shortest path, and impurities in the coolant often generate a path of least resistance that the electricity travels across. The source of this stray electricity is often from electrical engine accessories which have not been properly grounded. A missing engine or transmission ground strap can also cause the coolant to become electrified. Sometimes the path of least resistance becomes a radiator, a heater hose, or even the heater core. These components are often well grounded, and offer a ground path from the engine to the chassis by means of the semi-conductive path of the coolant.


Electrolysis can destroy your engine quickly. Although it’s semi-normal to have very small amounts of voltage potential in your coolant system, values greater than about a tenth of a volt can start reactions between the coolant and the metal in your engine. In particular, electrolysis affects primarily aluminum engine components, resulting in pitting and scaring of the aluminum surface. This eating away of the metal can cause coolant system leaks, and in particular, radiator leaks around aluminum weld. Aluminum components are always most vulnerable. On Aluminum engine blocks and heads in particular, electrolysis can be easily seen attacking aluminum. Figure 1 shows a picture of the thermostat area of a cylinder head that has been partially damaged by electrolysis. Notice how the aluminum has been eaten away, and eroded by the chemical/electrical reactions.

 

and in the case of a near totally Cast Iron Assembly as most of our 2nd Gen RAMs?

http://dodgeram.org/tech/gas/specs/5_9v8.htm

 

Intake manifold, Water pump, radiator, heater core are not cast iron. Cast iron sealing surfaces can pit also, just not as fast and not as deep.