I read where the GPR is energized by the PCM with a ground signal. I want to add a switch connected to ground WITH the PCM terminal attached (to control/extend glow-plug time)....would this harm the PCM and if so, I was thinking of adding a diode to the PCM lead so it can't get a reverse ground signal from the (installed) switch.

What do you think? Do I need a diode or can I just attach my "grounding switch" to the terminal along with the PCM lead? Also, does the block heater directly heat the coolant OR the oil? Thanks....

 

I would put the diode in place. It may not harm the PCM, but I'd say better safe than sorry with a diode being so simple to put in place.

Block heater heats the coolant directly, and not the oil.

 

Do you really need the glow plug on time extended? They stay on longer than the WTS light. Maybe just install a LED light to monitor glow plug on time?

I would isolate the switched ground from the PCM too. Don't know if it would hurt the PCM, but I wouldn't take any chances.

 

Thanks, I'll install the diode anyway.....need extended time for the GPs and anything that helps this beast to start is an advantage.

 

I have found with the GPR LED mod that the glow plugs stay on for 30 seconds to a minute or longer after start up depending on oil and ambient temps. Sometimes, I just wait a little longer after the WTS light goes out before starting on a cold day. The LED tells me the glow plugs are still energized.

 

Yeah, I have all the LEDS I need (I'm an electronic tech) so I'll install 2....a red one for the switch closure and and amber one for the glow-plugs' cycle.

 

That would be a great idea instead of having a swtich, though if it was really cold it would be nice to leave them on longer or in the summer just turn them off.

 

Not to hijack the thread or anything but I hate electronics so what do I need for the glow plug LED mod? (two wires and a led?)

 

https://www.ford-trucks.com/forums/7...wmriceman.html

 

I plan on using a DPDT (double pole, double throw) switch (Radio Shack) and using one side of the switch to light an LED (Red) indicator (showing the switch is on) and the other side of the switch to supply a ground signal to the PCM side of the GPR. (to over ride the PCM signal and energize the GPR).

I will also run a small lead from the glow-plug output side of the GPR to show when the glow-plugs are actually on with a second LED (Amber). I am also installing a diode in the PCM lead going to the GPR to avoid any ground faults that may hinder the PCM.

 

Dan (Kwik) did something like that years ago. Completely disconnected the GPR from the PCM and hooked up a momentary switch to activate them. That way, the GP's are only activated when he needs them to help start the truck. IIRC, he said that they'r not really needed until it starts to get cool, and even then he only has to activate them for a few seconds. Seems that would greatly reduce the wear on the GP's & GPR, as well as eliminate some drain from the batteries...especially during the summer months.

One thing you gotta remember is the reason the GP's stay on longer after the initial start is mainly to help with emissions, very similar to the AIH. Once the truck is running, it should build heat on it's own. The GP's staying energized after startup just help to ensure all the fuel is burned, cutting down on emissions and unburned fuel in the exhaust.

Heck, on my Cummins, I don't have any type of starting aids at all anymore. Cummins engines don't even have GP's, just an intake grid heater, and I've deleted the grid heater. So far, even down into the 20's, it hasn't had any trouble starting. My point is that I'm not 100% convinced that a diesel needs a heating aid to get it started, but no doubt that they do help on the really cold days.

 

Heck its only mid to low 30's at my house and my truck wont start. Gotta plug her in.

 

ANY diesel engine colder then 40 degrees ambient needs the assist of an alternative heating source to start smoothly (as is obvious by the MANY "can't start in the cold" threads) like glow-plugs, heat grid, coolant heater, etc.

The friction of constant cranking (without heat) will many times provide enough heat to get it started, and so the white smoke, romps and mis-fires.

Cold combustion in and of itself, is seldom a postive factor in "ignighting" a diesel engine in a cold environment. With added emission standards, coupled with a "let's get moving" society, newer diesels are easier to start due to the proper addition of strong and reliable heating devices. The older powerstrokes need all the assist they can get in this regard due to the heavy demands of a hydraulic oil injector system, higher compression and age/wear factors.

Once they are running, they are dependable, solid and powerful engines, but the overall (cold) starting process is their weak-link for sure. Any "enhancements" we can do to assist them to start in a smoother manner will, in my opinion, extend the wear factor and help them rapidly transition to proper operating (combustion) temperature.

 

Well if it is a newer Cummins, it has a heat strip to help out the starting process.

 

Mine does not, as I have removed it. There are no cold weather starting aids, other than a block heater, if I choose to use it. The newer engines do have a grid heater, yes. Like I posted though, mine is gone. I'm pretty sure I would have found any other type of heating device that needed to be hooked up when I did the swap...if there were any.