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Help On 3G Page

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Gary Lewis

Re: Help On 3G Page

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I don't know what size the shunt is. Do you?

As Steve83 pointed out, the shunt doesn't have to be replaced. The voltage drop across it is very small as the ammeter is very sensitive. But some people, like Ty, want to replace it, so I'm trying to figure out what size wire it should be replaced with. And the best way I could think of to do that was via the cross section of the wires it is feeding.

But, I may have a shunt that I cut out of Big Blue that I can measure. I'll look tomorrow.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

ArdWrknTrk

Re: Help On 3G Page

Administrator

37 is 10, and fuselink M is 14 AWG, which supports that.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Help On 3G Page

Administrator

Yes, and 38 is 12 and Fuse Link L is 16 gauge. And our shunt replacement supports both 37 and 38. But I don't think we should size by the fuse links. They are purposefully undersized by two notches to be the failure point, and we don't want our shunt replacement to be a failure point.

Bill's point earlier was very valid. The later trucks had the cab fed by a #4 wire running from the battery to the PDB on the driver's fender. And they don't have any electrical loads that our trucks didn't come with. Granted that wire is probably 6' long and our shunt replacement is maybe 1' long, so that changes things somewhat.

Tomorrow I'll see if I can measure the size of the shunt and the big yellow wire for #37 at C610. Since we are just extending that wire then using whatever gauge it is would seem appropriate.

Gary, AKA "Gary fellow": Profile

Gary Lewis

Re: Help On 3G Page

Administrator

I found the harness shown below and added some labels to the pic, so maybe we can use it in the write up.

And I measured the wires, as best I could, and referred to this table to come up with the wire sizes:

Big yellow wire going to the right from S202 is .115" in diameter, so should be a 10 gauge wire

Orange/black wire coming from the alternator to S202 is .115" so should be a 10 gauge

Shunt is .085", and while I can't find a good match in the chart, it appears to be smaller than 12 gauge but not as small as 14.

Given that, I'm going to suggest that we recommend that the shunt be replaced with a #10 wire. Thoughts?

Gary, AKA "Gary fellow": Profile

Tyler

Re: Help On 3G Page

I hate to distract from the conversation but as discussed, I removed my shunt wire and it was pretty burnt up upon examining it when I cut it out (fuselink J too).

If I keep my ammeter disconnected, am I safe to continue operation?

1985 F150 4x4 SB 300 I6: Comp 268 cam, '68 240 head, Offy DP, FI manifolds, Holley Sniper 2300, DUI street/strip distributor, BW T-18, Tuff Country 4" suspension lift, Yukon Offroad hubs + front and rear Duragrip LSD 3.73 ratio, 33-12.5/15s

Gear Vendors overdrive unit on order.

Oklahoma boy livin in Washington State. Retired submarine MMNCM (Nuclear Machinist's Mate, Master Chief)

Machspeed

Re: Help On 3G Page

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In reply to this post by Gary Lewis

I like what you're doing, Gary! Thank you! Yesterday, I was briefly looking over the stuff for my needs and wondering, where and what does this shunt look like??? I know now! Regardless, when putting stuff like this together, one has to think at the lowest level. Pictures are GREAT!!!

I've got my harness (alternator side) out of the truck. Would you like a picture of it? I have the 2G alternator in my 86.

John

"Blackie" - 1986 F150 4x4 - Mildly warmed over 351W HO - Original owner

Gary Lewis

Re: Help On 3G Page

Administrator

Ty - Which fuse link did you cut out?

John - Pics, please! That would help with the write up for the 2G.

Gary, AKA "Gary fellow": Profile

Tyler

Re: Help On 3G Page

I only have C610. Splice 202 and 203 are cut and removed. The 2 wires for ammeter are zip tied and disconnected (orange and yellow/green trace but green in your photo above). Thick yellow is routed to battery side of mega fuse along with the 12v continuous on yellow/white trace. Green/red trace is connected to green red trace from the painless harness (12v switched).

Everything else is removed. There is a photo about half way down on page 6 of the 3G Advice thread.

Gary Lewis

Re: Help On 3G Page

Administrator

You are good to go.

Gary, AKA "Gary fellow": Profile

Tyler

Re: Help On 3G Page

Whew!

Gary Lewis

Re: Help On 3G Page

Administrator

My only recommendation is that you put the 12v continuous on yellow/white trace on the alternator side of the megafuse. That way if the fuse should blow the regulator will still see the output of the alternator and not go bananas.

Gary, AKA "Gary fellow": Profile

Tyler

Re: Help On 3G Page

Understand all. Thanks for everything!

ArdWrknTrk

Re: Help On 3G Page

Administrator

In reply to this post by Gary Lewis

I agree with using #10awg to replace the shunt.
Should be plenty given how sketchy the rest of the cab wiring is

But I would suggest taking the entire harness shown and tossing it.
The alternator side of C610 can be useful if you're having your ammeter converted.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Help On 3G Page

Administrator

ArdWrknTrk wrote

I agree with using #10awg to replace the shunt.
Should be plenty given how sketchy the rest of the cab wiring is

But I would suggest taking the entire harness shown and tossing it.
The alternator side of C610 can be useful if you're having your ammeter converted.

Agreed. The "w/o shunt & w/o ammeter or voltmeter" version won't have C610. The "w/o shunt but with voltmeter" will have C610, as will the "with shunt & voltmeter" version.

I'll see what I can do a bit later today to get a potentially final version of the "w/o shunt & w/o ammeter or voltmeter" version to get that nailed down. If we can all agree on that then moving on to the other versions will be easier.

Yesterday I spent quite a bit of time trying to figure out how to use the schematics we have to tell the story, but just couldn't get there. Finally the three-step approach seemed to work:

Here's what you have

Here's what you are removing

Here's what it will be like when you are done

Gary, AKA "Gary fellow": Profile

Machspeed

Re: Help On 3G Page

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Gary Lewis wrote

Yesterday I spent quite a bit of time trying to figure out how to use the schematics we have to tell the story, but just couldn't get there. Finally the three-step approach seemed to work:

Here's what you have

Here's what you are removing

Here's what it will be like when you are done

I like that, Gary! I'll get you a good picture of my wiring harness this evening sometime. Thank you

John

"Blackie" - 1986 F150 4x4 - Mildly warmed over 351W HO - Original owner

Gary Lewis

Re: Help On 3G Page

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John - There's no hurry. Take the pic at your leisure as I have a lot of work to do before I need it.

Ok, here's the new "Here's what you are removing" page. Effectively it is the harness I showed earlier plus the other half of connector C610, and we will include that picture as well. Please let me know if y'all agree.

And here's the new "Here's what it will be like when you are done" page. Note that I've added the choke heater and the wiring to the EEC for the 4.9L. And the writeup will say that the things highlighted in yellow are what they are adding. Plus, we'll also need to suggest wire sizing for the run from the megafuse to the starter relay in the writeup. And, a megafuse size. But not in the schematic.

Thoughts? Upgrades? Concerns? Suggestions? I want to get this version "right" and use it as a template for the next versions, so now is the time for comments.

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: Help On 3G Page

Administrator

I think the stator wire will disconnect at C233 instead of C231.

And I think I would want to see C610 remain (on the cab side)

Beyond that, it seems a LOT easier to take the Y/w of the regulator pigtail to the output lug (because it reaches) than wherever the opposite end of the output cable hits the Megafuse.
The likelihood of voltage drop or something else effecting the reading of the sense wire between these two points is incredibly tiny.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Help On 3G Page

Administrator

I have no problem taking the Y/W wire back to the output lug. I'm just using the schematic from the '96 EVTM, and it shows it going to a fusible link, which I turned into a megafuse. And, as I think about it, if people use a pigtail from the salvage it might be wired that way. Either way works. We could discuss that in the verbiage.

As for the stator connectors, I can make that change as well. The EVTM says C233 is at the alternator and C231 is at the right front of the engine, so going with C233 gives longer wiring to reach the 3G.

But I'm confused on C610. I thought you said to remove it yesterday. I'm not bothered either way.

Gary, AKA "Gary fellow": Profile

kramttocs

Re: Help On 3G Page

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This post was updated on .

In reply to this post by ArdWrknTrk

I would also keep C610 and modify the alt side of it, leaving the cab side alone. This is user preference but would allow changing easily changing back. That may be planning for something that will never happen but one never knows. I picked up another C610 alt side and put my original one in a box.

I don't want to distract since mine is a 1-wire vs a 3G but on my modified C610 alt side it is:

Yellow -> 60A fuse -> battery
LG/R -> 1A fuse -> Red/Orange(so a loop)
Yellow/Light Green -> Ground

*I have a converted voltmeter*

Scott
'Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole

But there ain't nothin' wrong with the radio

ArdWrknTrk

Re: Help On 3G Page

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In reply to this post by Gary Lewis

I'm seeing a bit of wire before 233, and when I was looking at the 351HO diagram with John, it seemed like the spot had plenty of wire so it could connect the choke and his voltmeter, because of the stator triggered relay in the 351 HO.

But neither he or I are coming from a 1G, so it's hard to say?

I think the alternator side of C610 is pretty useless with a 3G, but the fact that most people can unplug it and say "ok, I'm done with everything here" is a big point.

It simplifies the process for the insecure, and offers another disconnect for 'key on power' if we can find a pin that fits the cab side of 610.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

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