Okay, guys, I know that I over-engineer most things I work on, and there is some degree of what people will call "wasted money" in those efforts, but while I am able to purchase the extra peace of mind, that's just my choice. I should never have to worry about my GPR again.

Instead of stopping at the Stancor relay upgrade, I went whole hog and bought a Tyco Electronics hermetically sealed contactor rated at 500 amps with a 100,000 cycle life rating (at 4 starts per day, 365 days per year, that translates into over 68 years of useful life). The ambient temperature range for the unit is also from -40°F to 185°F which should be adequate for where it sits on the motor. The link to the data sheet is here >>> http://relays.te.com/datasheets/LEV2...-1773439-1.pdf

I got a good deal on the unit from Onlinecomponents.com >>>http://www.onlinecomponents.com/te-c...tml?p=11635204, which was about $25-$45 cheaper than other places which had it. Total cost (including S&H) was $87.

 

SWEET. was looking at those AFTER the Stancor went in. Either way, the Stancor has given 7 years of service without a problem.

Be sure to post some pics once the install is done.

 

That should do it. Industrial strength contactor.

 

Pics will be posted, for sure. I'm getting so behind on installing new parts that I'm going to have to plan out a couple of mod weekends at the house before too long, but the GPR is going in as soon as it arrives. Been having some kinda sluggish cold weather starts, but I haven't seen any white smoke.

Regardless, at 230K miles, I expect the GP's and/or GPR are getting tired at this point and could stand a little proactive replacement. I still have several sets of GP's from back when we were getting them for anywhere from $0.01 to $1 each when Autozone was discontinuing them. I'm hoping to not have to install them in the truck because I want to sell it and replace it with a lower mileage 4WD Platinum in late spring/early summer.

 

subscribing

 

I too looked at those after I did the stancor. I also did the GPR led install while I was there. Simple yet effective information on when the relay is actually on.


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

 

The Tyco relay has a coil resistance of 11 ohms. That's 1.1 amp at 12 volts.

How does that coil current compare to both the Stancor and the OEM GPR?

Stancor's coil resistence is 21 ohms, so that's roughly 600 milliamps of coil current.

GPR-109 supposedly draws a full FOUR amps.

Don't know the rating for the OEM relay.

I would be concerned that I was not overloading the PCMs ability to dependably "sink" that much current.

Anyone know the specs for that PCM circuit's output (sink) driver?

New can-o-worms......

Pop

 

IIRC, the OEM is about 100 amps and the Stancor is about 200 amps.



I can't find the OEM specs either. However, people have been successfully using the Stancor for years without problems, so if we match it's resistance characteristics, we should be safe, correct? Perhaps this can be done by adding an external resistor into the wiring? Maybe something like this one >>> http://www.ohmite.com/cat/res_od_of_oa.pdf



NO DOUBT!! But I am grateful for your watchful eye all the same, Marv. I want to get some answers on these issues as well before I put something in that I thought to be a stellar upgrade if it is only going to end up frying my PCM.

 

This could be all solved by the addition of a power transistor, a small resistor, and a clamping diode, but that complicates things for non-electronics types. Weatherproofing and electrical insulation become issues, too.

Pop

 

Hey... I'm game for taking this on, especially since I already have the unit enroute.

If you could guide me on this, I'm happy to make a project of it and post plenty of pics and a PDF document for all to enjoy. Electronics is definitely a weak area of mine, but I'm all up for learning something new, and I have some time this coming weekend to make it happen.

 

Take a look at this page:
Transistor Circuits

Scroll down to the section entitled, "Using a transistor as a switch", including the part about "Protection diode".

Wire it as shown in the section farther below under "Choosing a suitable PNP transistor". I'd use something like a 2N3792.

You need to be mindful of isolation from ground, too. Remember, the transistor case has a connection.

Instead of solid-state, you could also use another, smaller, relay to drive the coil of the large one.

Sorta' like "Darlington'd Relays"

Pop

 

Anyone who has done the AIH delete and still has the relay it can be used to operate a big contactor without compromising the PCM.
No more difficult to wire than a doorbell.

 

OK. So this can be done, but am I now simply adding more parts which can go bad onto a highly reliable (yet overpowered) relay, and still end up risking burning up the PCM when one of the lesser components fails?

My goal is to "upgrade" so I can simply walk away from it for quite some time. It's counterproductive to add weaker parts into the system and end up with less reliability than I want to acheive.

 

I know.

I'm still looking for the truly "free lunch", too.

I think I will end up using a simple push-button switch in the cab, and control the GRP manually.

It's not rocket science for those who know how the glow plugs operate.

Pop

 

Wire in your own battery and ground for the contactor, and as Marv suggested, use a momentary switch to operate it when you need it.

Or do the AIH delete and use the AIH relay as a slave.