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saw smoke, wire getting hot


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#1 TR112

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Posted 01 March 2017 - 08:25 PM

So I have a new 100amp alternator installed and while driving tonight, I smelled electrical burn, then I saw a little smoke.

It was coming from under my steering column, and the plastic ignition housing had two melted impressions in it.

I unscrewed the housing and in the bundle of wires I saw the one that had melted the jacket/connector.

Tested it and observed after I turned the headlights on and saw it smoke.

Before I replace the connector, is there another fix I should do? Relay, big inline fuse, etc.?

Something is making it hot, don't think its my alternator.
SBC 350 / m21 4 speed

#2 TimZ

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Posted 01 March 2017 - 08:44 PM

So I have a new 100amp alternator installed and while driving tonight, I smelled electrical burn, then I saw a little smoke.

It was coming from under my steering column, and the plastic ignition housing had two melted impressions in it.

I unscrewed the housing and in the bundle of wires I saw the one that had melted the jacket/connector.

Tested it and observed after I turned the headlights on and saw it smoke.

Before I replace the connector, is there another fix I should do? Relay, big inline fuse, etc.?

Something is making it hot, don't think its my alternator.

So was the smoke/meltage specifically at the connector, or was it the wire itself?

 

If it's the wire itself, I'd think the first order of business would be to find which wire is getting hot and find out why it's flowing enough current to make things melt.  Sounds like a short somewhere.

 

If it's the connector, I'd check for corroded connections at the connector pins or where the wire is crimped to the pin.  A high resistance connection can cause heat buildup from the resistance.


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#3 TR112

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Posted 01 March 2017 - 08:55 PM

I should have taken a pic of it. It's a white jacket(melted) where it meets a flat connector,the wires look old but but they don't look bad.

By the looks of the plastic ignition cover, there are two melted impressions, side by side, but I only found one hot wire.
SBC 350 / m21 4 speed

#4 NewZed

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Posted 01 March 2017 - 10:05 PM

Not uncommon for the headlights switch itself, on top of the column, to get hot.  All of the headlights current flows through the switch.  There are relay setups out there.  You can go halfway on the relays, just the current through the switch but not the grounding circuit at the dimmer, and just save the switch.  Check the wiring diagram to see.  You didn't say what year your car is, I think there might be some changes over the years.  I have a 76 280Z and put a relay in front of the switch after the solder joint let go a couple of times.



#5 JSM

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Posted 02 March 2017 - 06:25 AM

It's probably such a high amperage now that the connection in the switch is dissipating in heat. Try cleaning the contacts.

My switch went from not working at all to working perfect.

http://www.kamikazer...ombo_switch.pdf

Edited by JSM, 02 March 2017 - 01:16 PM.

1971 240z
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1988 300zxt

#6 Greeko

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Posted 02 March 2017 - 09:54 AM

Yeah, Clean up all the connections around it. If all you did was replace an alternator and leave wiring..probably high resistance contacts causing higher current on wire to make connection...



#7 NewZed

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Posted 02 March 2017 - 10:05 AM

The contacts get pitted and holed after a few billion clicks so can still get hot if they're not refurbished well.  There was somebody that flipped the contact lever around and used the other clean, unpitted end.  Apparently there's an extra set unused in there, Can't remember the details.

 

The other part of the problem is that the running lights switch has the same issue.  So total heat buildup is pretty high.  With a simple relay, current through the headlights portion is reduced to almost nothing.  So you can take the switch apart or cut a few wires.



#8 Miles

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Posted 02 March 2017 - 01:06 PM

After you fix the headlight switch issue, install the headlight relay harness developed by a HybridZ member.  The harness is plug and play and will reduce the load on the headlight switch and allows you to use higher wattage headlights.

 

You can order the harness from the HybridZ member (he also repairs combo switches) who designed it:

 

 http://datsun-240z-upgrades.net/

 

Or buy it from MSA:

 

http://www.thezstore...ZS/PROD/12-4651


Edited by Miles, 02 March 2017 - 02:43 PM.

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