71,..Under-Dash,..Connector with Two Gray Wires

Discussion in 'Electrical Systems' started by Redliner, Oct 25, 2019.

  1. Redliner

    Redliner Member

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  2. Redliner

    Redliner Member

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    Could this connector be for the amp gauge?
     
  3. Jim Streib

    Jim Streib https://www.flickr.com/photos/121766713@N04/albums

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    The picture isn't the biggest but do those two colored wires off of that one connector go only to the one large square connector with the bolt sticking out of it ?. In other words, if the wires go to that plug then it may give some direction as to what it is for.

    It very well could be and by doing some tests you might be able to confirm this. Just like I was saying that normally a gray wire is an illumination wire and by testing a gray wire with a meter and doing things with the headlight switch it could confirm it is a illumination wire or not.

    Most amp gauge on the GM cars wire to two different points on the underhood wiring harness. They use the section of an underhood harness to act as a shunt to where most of the current goes through the harness but then the amp gauge measures this small difference between two points to give one a reading.

    I looked around a little on Lectrics site and I did not see any viewable wiring diagrams and it looks like they charge for it which is fine but maybe give them a call and see what they say about your mystery connector.

    Jim
     
  4. Redliner

    Redliner Member

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    Thanks everyone,..I'll get with Lecrtric Limited on Monday. I'll post the results for future inquiries.
     
  5. Scrappy1980

    Scrappy1980 Member

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    i have a question, I have a 72 Camaro and the dial does not light up very bright? is that how it was in 72, I mean i get light on the gauges but it is not bright.
     
  6. grzewnicki

    grzewnicki Veteran Member Lifetime Gold Member

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    That is the ammeter hook up, one black and one black with white tracer. When you said grey I immediately discounted it being the ammeter connection. Unless you're doing a restoration I would get rid of the ammeter, potential fire hazard since a lot of current goes through that wire to make the ammeter work, voltmeter better source of telling you battery/charging system condition. Mopar got it right, there ammeter was a shunt type and only needed a little voltage to work, less potential for fire. I just got done pulling the feed wire out of my harness (goes to starter big lug). If you look at the 1973 eng wiring diagram, 105 and 106 on the bulkhead connector are the wires that go the ammeter; http://nastyz28.com/camaro/wire/1973-camaro-u14engine-wiring.html. and then here you can see under the dash where they go to "gen"; http://nastyz28.com/camaro/wire/1973-camaro-taillight-wiring.html
     
    Last edited: Oct 27, 2019
  7. grzewnicki

    grzewnicki Veteran Member Lifetime Gold Member

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    Many people are using LED bulbs with success for a brighter gauge panel.
     
  8. Jim Streib

    Jim Streib https://www.flickr.com/photos/121766713@N04/albums

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    If these two wires are for an ammeter, then when talking with Lectric, I would ask them if where those wires connect into the underhood loom, are these wires on any type of protection like a fuse or fusible link on both ends. The link posted below of the wires off of terminals 105 and 106 show the one end going towards the starter which is a 16 Gauge Black wire (16 BLK SXL) protected by a 20 Gauge Orange Fusible Link (20 ORN THERMO HW) and then the other wire out of the bulkhead being a 16 Gauge Double White Stripe (16 BLK DBL WHT STR) going to a splice joint and close to this splice joint the wire is protected by another 20 Gauge Orange Fusible Link (20 ORN THERMO HW). If either ammeter feed wires past these fusible links were to short to ground, then the links should blow and open up the circuit BUT still allow the car to run.


    The GM cars I believe from the mid to late 60's to around the late 70's when the finally got smart and moved to putting in volt gauges instead of ammeters is they use two types of shunts but were never a full flow type such as what was on the Dodges and Chryslers.
    Here is a shunt used on some of the mid 60's Chevrolet's and the ammeter wired to each end of this shunt and then one end of the shunt went to the battery and the other to the alternator.

    [​IMG]

    [​IMG]

    On the above is shows an unsafe install due to no protection on the smaller gauge wires going to the ammeter gauge.

    Gm at some point then moved away from the clay style shunt and then started using two different points in the wiring harness such as one ammeter wire attached to the starter and the other to the main power wire splice close to the horn relay and alternator.

    I will say too that I believe a volt gauge will give more info than an ammeter but each has their place. Sometimes you want to keep originality while other times you want to really know what is going on as far as voltage levels.

    Jim
     
  9. grzewnicki

    grzewnicki Veteran Member Lifetime Gold Member

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    I got rid of the one wire to the starter but left the other wire in place since for some reason I did not get continuity from the wire at the horn relay to the ammeter connector, it did give me an audible signal that the wire at the horn relay went to ground at some point in its travels. I may have had the wrong wire since the wire diagram shows it going right to the relay but now in the discussion I'm thinking I checked continuity on the wrong wire, one had an orange fusible link and I believe the other wire had black. Gonna have to re-check it here shortly. It was nice to get rid of the wire going the starter, now there is only the bat charge wire and the purple wire going down there and I could use my old pipe that bolts to the block and protects the starter wires, before the big insulators on the fusible link was preventing me from passing the wires through it. I don't know why they use those huge insulators vice heat shrink, I guess it does help you find fusible links, you can't miss them.
     

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