Preparing for the big electrical upgrade which will involve the F650 lower panel and a bank of switches. First though I need to slam my Leece-Neville Idle Pro back in (higher output alternator, nominally 230A). To that end I want to set-up a manual glow plug switch* so that I dont fry the plugs themselves. Essentially by-passing the PCM command to activate the GPRelay.

1. What is the best entry point into the cab from the engine bay? Say a bundle of 2x 6ga wire (+&-) and 8x 16ga or so for relay triggering (lights, GPR, etc).

2. Is there any harm in running a dedicated ground wire into the cab - from the battery - as opposed to locating something to use under/in the dash panel? I cant imagine so, but maybe some smart people here have some insight. Basically this dedicated ground (and the dedicated power line) will backbone the bank of switches planned. I feel connecting directly from the batt(s) is better than jumping off existing wiring under the dash.

* My plan is to set up a circuit using a single pull/double throw momentary switch to trigger 2 different timed relays (time delay off) - which will trigger the existing GPRelay (with negative activation to replicate the PCM sig).

Why 2 times you ask? I would like a nominal 30 sec GP cycle for warmer weather starting, and then a longer cycle (like the nominal 2 min baked into the PCM) for the cold weather starting (note: in northern Maine). Since there is a risk of the L-N alternator supplying too much voltage at idle, compared to the anemic stock alternator, I dont want to run the risk of forgetting to switch off the GPR before I start cranking. This is why a momentary switch and the timers.

Forgetting to switch the GPRelay off? Well aside from age, usually when I start in the winter time I turn the key to engage the GPs and get out to a) clear snow off truck; b) deal with the extension cord for batt tender/block heater - dont need to be losing track of that thing only to get gobbled up by the snowblower, and c) those seats are awful cold to sit on while pushing a button for 3 minutes.

 

I'd just put the alternator in and leave glow plugs alone. If it ain't broke don't fix it. Pcm will turn glow plugs off/cycle them if voltage is to high.

Plus I've never seen a single person with proof of a issue fron high voltage. Just hearsay. lol

 

I've had a alternator like yours for almost 15 years and have never had any issue. Like stated above, there have been "stories" but nothing concrete have I ever read about in all my years of being a member.

 

one word of caution.

some high output Alternator are NOT controlled by the PCM,
mine is not.
it is a MechMan 340A

but, it might have been IF, a shade tree mechanic had not butchered up the OEM wire harness to the alternator.

I had to run a new wire from the key-switch to the Alternator 'on' terminal ( I ) ??

this causes it to output 14.9 volts immediately, so I have to watch the DVM in the power port to verify that the glow plugs are OFF... I have a delay relay to install as soon as, it stops raining here

 

I have had this alternator on 2x 7.3s. The first was an e99. After less than a year 5 of the GPs (I think) werent producing (they did check out in the year before I installed the new alt). Granted they could have been original and their time was up. The 2nd is my 2002 (without the GPM or GPCM). Again less than 1 year after putting the L-N on, I found that 4 of the GPs werent producing (after checking resistance soon after I acquired the rig). Coincidence? Their time was up? I pulled the alternator off as an abundance of caution.

Plus I believe where the truck lives plays a role. With the PCM setting the ON time based on oil temp (for the most part), the maximum ON time appears to be when temps less than 32F, with the longest time when EOT<14F. For me I am nearly 6 months where average temp is below 32, and 3 of those months are lucky to see 14 as an average. Thus the times my GPs are on are the longest, increasing the impact of higher voltage on them. It could be that for some, their exposure to longer ON times is minimized, thus reducing the possibility of "high" voltage negatively impacting the GPs. @Y2KW57 has posted some good info from Beru (the designer and manufacturer of the GPs) about their voltage limitations. Plus I think there is a TSB on the matter.

Like I said, getting authentic GPs is getting to be challenging. Also the risk of a tip falling off and pin-balling in the cylinder would be a game over for me with this vehicle. Plus, it is a cool science project.

Pros/Cons on switching the GPs aside, I still have the main question: what is the best routing into the cab with a bundle of wires?

 

If you have a automatic use the little block off plate for clutch master cylinder. Drill a hole and put a grommet in it.

 

ZF6 here. Good thought though

 

@pvdiag

Use the four OEM Ford pass through wires that are already passed through the firewall, and have blunt cut heat shrunk capped pigtails under the hood and under the dash.

@RacinJasonWV recently posted a photo of the underhood location of these four pass through wires:

 

Yeah, I keep forgetting about those. Thanx for the reminder! As a sig wire to trigger a relay, that size should be fine.

I still want to bring 2x 6/8ga lines in from the batts to power the switch bank. Plus I will need 1x more relay trigger lines (above noted GPRelay, fogs/driving up front, headache rack floods, rear floods, and a spare (future camper/topper feed as long as the domestic authority is onboard with one of those snazzy new aluminums that are coming out?) - for a total of 5 triggers. So I believe I will still need to come up with a firewall penetration.

 

This is what I did for the EGT and boost lines and was planning to recommend…

I wonder, where does our automatic cable exit the cab and would it provide a similar opportunity for the ZF6 crowd?

Personally I like your timed relays and your logic behind them (yeah I can be forgetful too, which means plan ahead!)

In my opinion, a dedicated ground would be a good practice even though I don’t do this.