What is this wire attached to the OEM stock starter cable?

Gypsy62 · **Posted:** Sat Jan 16, 2021 4:28 am

Inquire because my 2-battery setup requires replacing the stock cables. What I'm not completely absorbing is why wouldn't a 14-gauge wire that is presumably sending a "cranking" signal to the ECM be located closer to the ignition switch itself??? Seems weird that it routes all the way down to the starter tab.
Thanks!

Tags: CRD starter wiring positive function functions weird extra wire cable

Billybob · **Posted:** Sat Jan 16, 2021 7:51 am

Looking at Page 8W-21-2 for the 2006 KJ that Grey Wire seems to go from the Starter to the "Module Glow Plug (Diesel)" on Page 8W-30-16. It does show a splice on it, S123, but that could happen later at the actual connection to the "Module Glow Plug" ! :wink:

WWDiesel · **Posted:** Sat Jan 16, 2021 1:22 pm

That is correct, it supplies power (12v) directly to the Glow Plug Module from the battery cable at the starter on the diesel models.
WD shows it as a 10ga. gray wire.

Gypsy62 · **Posted:** Sat Jan 16, 2021 2:25 pm

Taking a better look at the diagram above [Thanks!] It's evident that the wire doesn't route through the ECM but triggers the glow-plug relay directly. Makes sense.

It still seems odd that the relay receives the cranking signal from the starter terminal instead of the ignition switch, but maybe I'm missing something. Maybe supply-amps?

I don't recall a similar wire on the Ford 6.9/7.3's I've wrenched. Other Chrysler diesels with this setup?
Thx

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

The CRD uses Bosch EDC ... I wouldn't expect similarity to Ford or other Chryslers. Maybe VW or Mercedes though.

WWDiesel · **Posted:** Sat Jan 16, 2021 4:39 pm

ECM is still in control of the Glow Plugs!
The Glow Plug Module has 9 wires, 1 ground wire, 1 ASD wire, 2 ECM inputs, 1 12v power supply from starter motor lug, and 4 outputs to Glow Plugs.

Gypsy62 · **Posted:** Sat Jan 16, 2021 7:37 pm

In case the pos cable ever shorts, this ECM-defending fuse is worth noting:

I'm going to try to locate/photo/post it for reference.

Gypsy62 · **Posted:** Mon Jan 18, 2021 2:43 am

The glo-plug relay is mounted on the port-side wheel-well directly below the ECM. Here's the fuse [circled] for the wire that routes from the starter pos terminal, located where the wire feeds into the relay's connector-plug with the other glo-plug control-related wires. I didn't feel like tearing it apart just to satisfy my curiosity but now you know another thing to check [fuse] if you're having glo-plug system issues:

Also, the spec may say that is a 10ga. wire but stripped to copper it looks, at best, 14ga.:

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

I think what you're looking at is a fusible link. The writing on the insulation indicates the size of wire it is designed to protect (10ga), not the size of the wire it actually is. Typically speaking, fusible links are two AWG sizes (four numbers) smaller than the size of wire they're rated for... eg, fusible link for 10ga wire will be 14ga. The heavy-duty insulation is there to prevent molten metal when it blows from causing collateral damage. It's important they be installed & connected in specific way to ensure they function properly.

Billybob · **Posted:** Tue Jan 19, 2021 2:20 am

It definitely makes sense that either this Gray wire is a Fusable Link or it goes onto a fuse right before the Glow Plug Module.

That Gray wire comes off the thick red wire that turns the Starter motor over..unfused....so some protection is needed for the glow plug modules. :wink:

Good thing to bear in mind for glow plug issues!

My 2002 Export CRD is totally different...uses two fat relays to supply +12 volts direct to the 11 volt glow plugs...one volt is dropped over the relay contacts. No checking of the glow plugs is performed....only complains if the Relays are pulled out! :wink:

Gypsy62 · **Posted:** Tue Jan 19, 2021 11:08 am

Great info!
I cut it near (2") the stock starter terminal so I doubt I compromised it's engineered function.

Fwiw, the 2-battery install is complete and 'working'.
Only issue is 20yo unused (diode) isolator is dead. Temporarily rigged it as standard parallel setup. Around a gazillion CCA's, the starter is enjoying the little blue pills.
When wrapped, I'll start a new thread and promptly be educated on all my f-ups. Normal.

Thanks!

WWDiesel · **Posted:** Tue Jan 19, 2021 3:57 pm

Billybob wrote:

It definitely makes sense that either this Gray wire is a Fusable Link or it goes onto a fuse right before the Glow Plug Module.
That Gray wire comes off the thick red wire that turns the Starter motor over..unfused....so some protection is needed for the glow plug modules. :wink:

Good thing to bear in mind for glow plug issues!

There is no regular fuse or fuse holder in the circuit from the starter lug to the GP module.
If you look closely at the WD, it says: "FUSED (+)" at both ends of the circuit, so yes this is a fusible link wire.

Gypsy62 · **Posted:** Wed Jan 20, 2021 2:50 pm

Yikes! So I guess this GP wire has to be fused near where it "Y"'s off the new starter cable @ the starter pos term.
Thanks for the heads-up!
Mated to the full-force of about 1900CCA's from two batteries, it wouldn't require much of an abrasion-to-ground to turn that 18" 14ga. wire into fireworks.
A greatly appreciated reminder & a prudent precaution.

[A fact made clearer to those of us who have had the pleasure of melting 12v wiring. The fond memory of an early lesson in amps+distance<gauge-fusing=fire: small winch + 15' of 12ga. to battery= burning wood floor in car hauler :ROTFL:

]

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

The grey wire that runs between the starter and the glow plug module *is* the fuse. A fusible link is a specially crafted length of wire - a specific length wire with a specific gauge coated with special insulation and crimped (NOT soldered) in place. When the amperage being drawn across is surpasses a specific threshold, the wire melts breaking the circuit. That's why it should not be modified.

WWDiesel · **Posted:** Wed Jan 20, 2021 4:22 pm

Reminds me of a Ford truck I once worked on, had a short in the trailer wiring he connected to his truck and it kept blowing a fuse, so he stuck a piece of stripped wire (jumper) in its place because he said he ran out of fuses. Needless to say, it completely melted (cooked) one wire in the wiring harness all the way from the trailer connector through the wiring harness all the way through the dash and to the fuse box. It had more problems and shorts than you can imagine, that wire melted into other wires all through the harness and shorted out all sorts of things and caused all kinds cross connections and crazy problems! Price of a new wiring harness was way beyond his means so he talked me into repairing the harness. I had to open that complete harness up and pull out the burnt wire and repair every wire in the harness where it had melted into another wire. It took me hours upon hours to repair all the damage along with R&R the dash to get at the harness and running a new wire for the melted one through the whole vehicle. Of course I replaced the fuse with the correct amperage one and told him never to do that again. I think he learned his lesson. :shock:

And to top it all off, he said he felt like I overcharged him for the repair. I told him: next time, take it to a Ford Dealer, but don't come back to me for any repairs. Never did hear from him again, and that was a blessing. :wink:

Moral of this story; you DO NOT want any burnt or melted wires.

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

Man, you just cannot overstate how important proper circuit protection is. Taking shortcut and defeating safety systems is a fast pass to financial hurt. Definitely a scenario where aim twice/cut once applies.

Gypsy62 · **Posted:** Wed Jan 20, 2021 7:59 pm

Riiight. Sorry (duh). I guess I always think of a "fusible link" as being a much shorter line (<6"). Feel free to cite me for exceeding the legal limit of lessons-per-hour. Thx!

I didn't "modify" it, per se, just "relocated" it to the new starter pos cable. Stripped at end 1" & then crimped it inside the 1-gauge sleeve-terminal with the new pos cable @ starter. Hopefully, that will adequately replicate the stock function.
So far, no fire.

Thanks again!

What is this wire attached to the OEM stock starter cable?

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