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Old 04-03-2018, 10:56 AM   #1
Green67Stepper
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Melted Red and Pink wires at Ignition Plug

Truck is a 67 with a 5.3 LS Swap. As you can see from the picture, my Red 12v feed wire and Pink IGN COIL wire are melting at the ignition plug. I know the pink wire feeds through the firewall bulkhead and originally fed the Ignition coil. I believe it also split off and feeds something on the underdash fuse panel. When I swapped to the LS, I did away with the stock wire coming out of the firewall bulkhead on the engine side and ran a new wire to feed with Engine Harness with 12v to the PCM etc. I also have Relays for Fuel Pump and Electric Fans. What would be causing these wires to melt?


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Old 04-03-2018, 12:14 PM   #2
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Thumbs up Re: Melted Red and Pink wires at Ignition Plug

Several years ago I had the same thing happen. It was the plug in itself. The plastic had gotten hot over the years and it finally gave in. Those two wires carry the most heat. I bought a new connector and replace the whole thing. It's been fine ever since.
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Old 04-03-2018, 03:51 PM   #3
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Re: Melted Red and Pink wires at Ignition Plug

Andy's right about the plug, but if you are melting wires then you are pulling too much current through them. If you have relays and the ignition switch wires are actuating the relays, you should not be pulling very much current through them.

The large red wire is the ignition feed wire and the pink wire feeds the ignition coil, the fuse panel, and the gauge cluster.It feeds the key on circuits and the large red wire feeds the fuse panel for the constant on circuits, hazards, brakes, front parking lights, taillights, dome lights and cigarette lighter. It also feeds the headlight switch.

The large brown wire on the key is the accessory feed and it powers the rest of the fuse panel, wipers, turn signals, and the heater switch.

You should have a main wiring junction in the engine compartment where the battery, alternator, cab feed wire, and the cooling fans tie together. You should feed the PCM relay, the fuel pump relay, and the cooling fan(s)relay from here.
Then the key switch pink wire will control these relays whe the key is on.

Here is a complete diagram on the 67 to 72 trucks stock from the factory.

It's the second post in the thread.

http://67-72chevytrucks.com/vboard/s...185856&page=13
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Old 04-03-2018, 03:56 PM   #4
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Re: Melted Red and Pink wires at Ignition Plug

I'll assume that you have converted the alternator to either the SI or CS system to provide more current for the truck wiring. If so then you definitely need the main junction in the engine compartment.
If you want to use the original battery gauge then you have to wire it similarly to the stock system.
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Old 04-09-2018, 08:00 AM   #5
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Re: Melted Red and Pink wires at Ignition Plug

Quote:
Originally Posted by VetteVet View Post
Andy's right about the plug, but if you are melting wires then you are pulling too much current through them. If you have relays and the ignition switch wires are actuating the relays, you should not be pulling very much current through them.

The large red wire is the ignition feed wire and the pink wire feeds the ignition coil, the fuse panel, and the gauge cluster.It feeds the key on circuits and the large red wire feeds the fuse panel for the constant on circuits, hazards, brakes, front parking lights, taillights, dome lights and cigarette lighter. It also feeds the headlight switch.

The large brown wire on the key is the accessory feed and it powers the rest of the fuse panel, wipers, turn signals, and the heater switch.

You should have a main wiring junction in the engine compartment where the battery, alternator, cab feed wire, and the cooling fans tie together. You should feed the PCM relay, the fuel pump relay, and the cooling fan(s)relay from here.
Then the key switch pink wire will control these relays whe the key is on.

Here is a complete diagram on the 67 to 72 trucks stock from the factory.

It's the second post in the thread.

http://67-72chevytrucks.com/vboard/s...185856&page=13


Quote:
Originally Posted by VetteVet View Post
I'll assume that you have converted the alternator to either the SI or CS system to provide more current for the truck wiring. If so then you definitely need the main junction in the engine compartment.
If you want to use the original battery gauge then you have to wire it similarly to the stock system.
Thanks for the info. That diagram helped a lot. I looked at it 100 times this weekend probably. So I did wire in a new ignition pigtail I got from Brothers. The only thing different was that my stock pigtail didn't have the large brown wire on it, only the small solid strand brown/white wire. (My truck originally was a 250/3speed with the 3 hole cluster) On the new pigtail, I just didn't wire anything to the large brown wire.

What I am still a little confused on is what is pulling so much current that its melting the pink and red wires. I wouldn't think it would be anything on my motor harness, since its running 3 relays and 8 individual fuses for all those electronics.

My stock fuse block isn't running much extra stuff either. I have the radio and cigarette lighter tied together and running off the radio terminal. I have my TCC switch running off one of the unfused ignition terminals and I then have my OBD2 port (with Gauge Reader), SES light, and a Autometer 3-pod mechanical gauge set running off the other unfused ignition terminal.

Should I pull all that off the stock fuse block on run a new power wire from the battery with relays/fuses? What else should I check? (I really hate wiring....) I also thought about adding a circuit breaker to the main feed off the battery and getting rid of that fusible link wire before the junction block. Is this a good idea and if so, what size circuit breaker would be good?

I am running just a single wire alternator too.
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Old 04-09-2018, 08:26 PM   #6
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Re: Melted Red and Pink wires at Ignition Plug

///////////////////////////////////////////////////////////////////////////////////////

Quote:
Originally Posted by Green67Stepper View Post
Thanks for the info. That diagram helped a lot. I looked at it 100 times this weekend probably. So I did wire in a new ignition pigtail I got from Brothers. The only thing different was that my stock pigtail didn't have the large brown wire on it, only the small solid strand brown/white wire. (My truck originally was a 250/3speed with the 3 hole cluster) On the new pigtail, I just didn't wire anything to the large brown wire.

OK I didn't notice the 67. Mine is too and the large brown wire is the accessory wire to the fuse panel. The 67 key has no accessory terminal so no brown wire (12 gauge) in the harness. The smaller wire is the exciter wire for the alternator and it's probably connected to the pink ignition wire.

What I am still a little confused on is what is pulling so much current that its melting the pink and red wires. I wouldn't think it would be anything on my motor harness, since its running 3 relays and 8 individual fuses for all those electronics.

About the only thing you can do is put an inductive ammeter on the large red wire on the key switch and turn everything on and read the total amps it's pulling to see if it's more than the wire is rated for. First off is the wire just getting warm or is it actually melting and are you thinking that over time it might get like it was when you changed it?

My stock fuse block isn't running much extra stuff either. I have the radio and cigarette lighter tied together and running off the radio terminal. I have my TCC switch running off one of the unfused ignition terminals and I then have my OBD2 port (with Gauge Reader), SES light, and a Autometer 3-pod mechanical gauge set running off the other unfused ignition terminal.

Why don't you have the torque converter clutch wired through the brake switch so it disconnects when the brakes are applied? Seems like it would be engaged all the time wired to the IGN-UNfused. How does it disengage when you're at a red light?

The OBD2 reader port is normally wired to the cigar terminal on most cars cause it's hot all the time. I don't think it pulls any juice when the car is turned off, but maybe it does.

The check engine light wouldn't pull much but I would think it would be wired through the OBD2 reader unless it's triggered by the engine sensor circuits and the PCM.

Should I pull all that off the stock fuse block on run a new power wire from the battery with relays/fuses? What else should I check? (I really hate wiring....) I also thought about adding a circuit breaker to the main feed off the battery and getting rid of that fusible link wire before the junction block. Is this a good idea and if so, what size circuit breaker would be good?

It might be a good idea to PM Andy, he and I are good friends and we have met in person, and ask him what he did with his. He has an LS conversion with the 700 and a whole bunch of electronics and relays. I could make some suggestions and guide you through it but he might be able to get you there quicker.
One good way would be to run a firewall mounted fuse panel with a main junction there.

I wouldn't use a circuit breaker in place of the fusible link because it would not disconnect completely in case of a short. It would just sit there and buzz like a tree frog, plus the fusible links are designed to compensate for current surges before they blow.

I am running just a single wire alternator too.
Are you running a newer style CS that doesn't have to be revved to start charging? They don't compensate for downstream voltage drops unless the sensing is done through the PCM. I think the 96 or newer ones do.

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Old 04-09-2018, 08:34 PM   #7
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Re: Melted Red and Pink wires at Ignition Plug

BTW your photobucket pics are not coming through.
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Old 04-09-2018, 08:56 PM   #8
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Re: Melted Red and Pink wires at Ignition Plug

* My alternator is the stock LS one, off a 2000 5.3l

* As far as I can tell the wires are just getting warm enough at the ignition plug to melt the plastic surround. No actual wires have melted yet. When that plastic melts and then cools off it caused the ignition plug to warp and loose connection.

*The TCC wired to a new brake switch. from my understanding it needs power when the brake is not applied and then when it is applied the brake switch cuts power. I'm getting my power from that unfused IGN terminal.

* I'm running a OBD2 port reader for my LS gauges so it needs to be cut on and off with the ignition or it would never go off. That's why I have it on the unfused IGN terminal. I just have a jumper wire off that to power my SES light and to power my Autometer backlights and Volts Gauge.



OBD2 Gauge


* The reason I ask about the fusible link wire off the main battery supply is because I think I replaced it will a solid 12g wire last year because it got torn or something. At the time, I didn't realize that's what it was.

I know my LS motor harness needs 12v constant and 12v keyed power. I think I need to get the 12v constant power off the truck harness and run a new power wire right off the battery for that. I really don't remember where I am getting 12v constant right now. I'm pretty sure my 12v Keyed power is coming from them IGN COIL terminal on the firewall bulkhead. I know I replaced that stock wire, with a new one during the swap, because it was a resistance wire or something like that...

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