Burn at yellow wires of big connector.

[Lovely Bunny]

Hi all, and thanks in advance for any help...I'm learning as I go so this might be a real noob sort of question.

I was replacing my blower motor and disconnected a big connector that runs to the glow plug relay, just so I could get a little more room to maneuver. Got the new blower motor in and reconnected the thing and now she's having trouble starting. Slow crank, a little catch or two but never really turns over. Smelled a little plastic burn smell and found that the fat yellow wires going into the connector were hot to the touch and had a little burn on them (see pic below, yellow wires on the left). So my question is...what do I do? Do I just need to replace the connector?

Also oddly the warning buzzer that sounds when you have your keys in the ignition is suddenly buzzing away...it had never worked before. Maybe more evidence of a janky connector? Thanks much friends, happy weekend.

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[gandalf]

Those heavy yellow wires are indeed feeding the glow plug controller. If they are compromised that will affect the glow plugs, and you will have a more difficult time starting.

I melted those same yellow wires on my truck, melted them much worse than you have. I simply cut them out and powered the glow plug controller from another source.

If your engine is turning over too slowly that will also cause difficulty starting. That would indicate, probably, either the batteries getting low, or the starter getting too old. Start with the easy thing and charge the batteries.

The white wire, third from the right, would worry me. It looks as though it has also melted the connector.

 

[chris142]

Very common. Ford used small connectors there. Can't take the load.

 

[franklin2]

Hopefully the connections on the smaller wires are still ok, they were on mine. Like was said, this is a common problem. The two yellow wires are parallel conductors, so you do not have to keep them in order. Just cut the yellow wires close to the connector on both sides, so you have 4 ends. Then join the two ends coming from the engine side to the two ends coming from the pass side fender.

You can see how handy it is to take this connection apart for any sort of engine work. So I still use the original connector for the smaller wires, and I crimped ring connectors on the ends of the yellow wires and then used little bolts to bolt them together, so I could take them apart again. They make fancier high current connectors that you can take apart, if you want to go that route. My method and a little tape is the cheap way to go, but it works.

 

[Lovely Bunny]

Thanks folks!

 

[IDIBRONCO]

You can see how handy it is to take this connection apart for any sort of engine work. So I still use the original connector for the smaller wires, and I crimped ring connectors on the ends of the yellow wires and then used little bolts to bolt them together, so I could take them apart again. They make fancier high current connectors that you can take apart, if you want to go that route. My method and a little tape is the cheap way to go, but it works.

Man did I ever used to wish that more people had a similar line of thinking when I was R&Ring these engines for a living. It was SUCH a PITA to have to snake the entire engine wiring harness out from the injector lines and then have to snake it back in after the new engine was installed. Thank you for that advice!

 

[Fixnstuff]

This is the typical repair method. (Photo below) DO IT ASAP before that connector melts and burns and ruins all of the other wire connections.

You will NOT find another plug like this one anywhere. so don't even think about trying to replace it with an "equal"
For now use the connector for the small wires and bypass the connector with the glow plug wires. This photo is from my truck:

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Those are 10 gauge wires, and as I recall with 16 conductors. NO NEED TO REPLACE THEM they are in FACT 100% correct for this application and the load. Originally the connector had a moisture sealant grease on the pins connecting inside which has long since dried out/deteriorated. The connector itself is old and brittle. Eventually a tiny bit of corrosion formed in those glow plug wire pin connectors and the connection began to arc and generate HEAT, INCREASING THE RESISTANCE and thus increasing the heat until it burns the pin connectors wire insulation and melts and burns that end of the connector.
You are not getting an adequate electrical connection now, which is where your starting problem is SO FIX THAT ASAP

 

[Fixnstuff]

PS: Those are 10 gauge NYLON butt splice connectors. You will need a high leverage good quality wire crimping tool to get a good tight connection when crimping 10 gauge connectors. You don't want that connection to slip apart, so make it good.

 

[Fixnstuff]

>snip

You can see how handy it is to take this connection apart for any sort of engine work. So I still use the original connector for the smaller wires, and I crimped ring connectors on the ends of the yellow wires and then used little bolts to bolt them together, so I could take them apart again. They make fancier high current connectors that you can take apart, if you want to go that route. My method and a little tape is the cheap way to go, but it works.

Those two runs of 10 gauge wires are rated for 50 amps each so the combination of both wires are rated for up to 100 Amps. Contrary to misinformation floating around, the ZD9 glow plugs circuit does NOT draw over 100 AMPS. People who think the circuit draws a lot more, don't understand how the solid state controller works. Finding a connector (that you can take apart) capable of handling 100 amps (two wires) is not going to be easy to find - if at all and it's going to be VERY LARGE. I could not find one and I spent months online looking for one. What I was finding that would work, were circuit breakers but they were also very large so I opted for the but splice connectors.
YOUR described method is good. I've seen your posts mentioning that before. As long as you can keep those bolts and lock nuts insulated from ground.
You could actually solder the two yellow wires into a single ring connector and the two Black/Orange wires into another single ring connector and bolt them together with a single bolt. The ring connectors would need to be rated for up to 100 Amps at 12 volts though. I've used them (copper) on GP: harnesses but I forgot what size they are. Pretty sure 5/16 inch (for 5/16 cable)

 

[chillman88]

Finding a connector (that you can take apart) capable of handling 100 amps (two wires) is not going to be easy to find - if at all and it's going to be VERY LARGE

Actually these are ideal
They might be a little big but they're overkill for the circuit while maintaining easy disconnecting. However they're not as cheap as eyelets and a bolt, they would be better insulated.

https://powerwerx.com/anderson-powerpole-connectors-75amp

Contrary to misinformation floating around, the ZD9 glow plugs circuit does NOT draw over 100 AMPS. People who think the circuit draws a lot more, don't understand how the solid state controller works

When the plugs are initially powered the amperage DOES exceed 100Amps. That has been verified. However the current does quickly decrease. Can't quite figure out how you think the controller meters the amperage when all it does is open and close a relay.

 

[Philip1]

I measured the amperage going into the glowplug controller and found it pulled over 260a then started tapering down. It was enough to pop a 250a breaker consistently so I had to switch out to a 300a breaker.

 

[Jim993]

I added a section of heavy yellow wire and used wire nuts and dielectric grease for the connections on mine about ten years ago. No issues since.

 

[typ4]

I take the yellow wires completely out of the harness butt connector them together with good quality butt connectors and then when I want to remove that harness if I ever need to you can just unbolt it and it's fusible links from the starter relay easy peasy less connections.