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amp gauge: a right and wrong way #2500419
05/25/18 07:10 PM
05/25/18 07:10 PM
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Houston, Tx
hemi68charger Online content OP
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Hey guys...

This may sound like a VERY silly question... But, when it comes to our era amp gauges, this case a 67 Plymouth, is there a proper "left" and "right" post when attaching the red and black wires? I would think the gauge just senses the current regardless of the way it is traveling through it... I could be wrong...

I went to hook up the battery after reinstalling the instrument cluster and dang, the fusible link went up and smoke. Smoke even came out of the ground point on the radiator core support where the negative battery cable body ground attaches... Never saw that one before... I quickly removed the positive cable from the battery and checked the wiring under the dash at the bulkhead connector and outside on the firewall. The only wire that seems to have been affected is the fusible link... Whew....


Troy
Houston Mopar Connection Club
'69 Charger Daytona 440 - auto - 4.10 Dana (now with 426 hemi)
'69 Charger 500 440 - 4speed - 3.54 Dana
'70 Road Runner 383 - 4speed - a/c (now with 440)
Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500431
05/25/18 07:51 PM
05/25/18 07:51 PM
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clarks summit pa
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Not sure about a 67, but I just did a dash swap on my cuda and underneath the studs, it was stamped on the back showing which wire went to which stud. By reversing the wiring it may affect the gauge reading as to whether it is drawing current or charging. Not sure though.


1973 Cuda 528 all aluminum Hemi, 4 speed, 3.23 Sure-Grip, (JA5) Silver Frost Metallic 1973 Challenger Rallye 340 1985 W150 Power Ram prospector 1986 Camaro IROC-Z 305 tpi
Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500434
05/25/18 08:06 PM
05/25/18 08:06 PM
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Posts: 27,812
Hamtramck, PA
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If you run a positive wire to a ground stud, chaos will ensue.

Here is the back of a 1970 Duster cluster just so you can see how the newer ones were marked, check yours for sure!

1970 red alternator wire lug on dash.JPG
Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500437
05/25/18 08:13 PM
05/25/18 08:13 PM
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Grand Prairie,Texas
stumpy Offline
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There is no ground side on the amp gauge. It is just in and out. That is why when you bypass the gauge you just hook both wires to one terminal or together. If you reverse the wires the gauge just reads backwards. It sounds like you have a dead short somewhere.

Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500438
05/25/18 08:15 PM
05/25/18 08:15 PM
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Posts: 16,192
Mass
DAYCLONA Offline
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Originally Posted By hemi68charger
Hey guys...

This may sound like a VERY silly question... But, when it comes to our era amp gauges, this case a 67 Plymouth, is there a proper "left" and "right" post when attaching the red and black wires? I would think the gauge just senses the current regardless of the way it is traveling through it... I could be wrong...

I went to hook up the battery after reinstalling the instrument cluster and dang, the fusible link went up and smoke. Smoke even came out of the ground point on the radiator core support where the negative battery cable body ground attaches... Never saw that one before... I quickly removed the positive cable from the battery and checked the wiring under the dash at the bulkhead connector and outside on the firewall. The only wire that seems to have been affected is the fusible link... Whew....



Sounds like you screwed the pooch, while the gauge is designed to work in series, there is correct manner in which the current flows thru the gauge, should be marked with "red", or "S" on the primary terminal of the gauge to receive the red wire, black/dark blue on the other terminal

FYI, replace those "paper" mounting insulators on the posts with some nylon washers...make sure your isolating the studs properly in the dash cluster

Re: amp gauge: a right and wrong way [Re: stumpy] #2500439
05/25/18 08:17 PM
05/25/18 08:17 PM
Joined: Aug 2003
Posts: 8,650
Houston, Tx
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Yeap. That is what I was afraid of. Wondering if the starter relay could cause it. Otherwise, I am going to pull the cluster out again and see if the amp gauge shifted some how on the frame and touching it.


Troy
Houston Mopar Connection Club
'69 Charger Daytona 440 - auto - 4.10 Dana (now with 426 hemi)
'69 Charger 500 440 - 4speed - 3.54 Dana
'70 Road Runner 383 - 4speed - a/c (now with 440)
Re: amp gauge: a right and wrong way [Re: DAYCLONA] #2500452
05/25/18 08:52 PM
05/25/18 08:52 PM
Joined: Aug 2003
Posts: 8,650
Houston, Tx
hemi68charger Online content OP
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Originally Posted By DAYCLONA
Originally Posted By hemi68charger
Hey guys...

This may sound like a VERY silly question... But, when it comes to our era amp gauges, this case a 67 Plymouth, is there a proper "left" and "right" post when attaching the red and black wires? I would think the gauge just senses the current regardless of the way it is traveling through it... I could be wrong...

I went to hook up the battery after reinstalling the instrument cluster and dang, the fusible link went up and smoke. Smoke even came out of the ground point on the radiator core support where the negative battery cable body ground attaches... Never saw that one before... I quickly removed the positive cable from the battery and checked the wiring under the dash at the bulkhead connector and outside on the firewall. The only wire that seems to have been affected is the fusible link... Whew....



Sounds like you screwed the pooch, while the gauge is designed to work in series, there is correct manner in which the current flows thru the gauge, should be marked with "red", or "S" on the primary terminal of the gauge to receive the red wire, black/dark blue on the other terminal

FYI, replace those "paper" mounting insulators on the posts with some nylon washers...make sure your isolating the studs properly in the dash cluster


Hey Mike.
On the back of this GTX's circuit board there isn't any markings, either from not having them to begin with or age and many hands touching it over time. Done plenty of Rallye clusters and they do have a RED marking on the housing. Not so on this GTX. Like your idea on the nylon washers.

Last edited by hemi68charger; 05/25/18 08:53 PM.

Troy
Houston Mopar Connection Club
'69 Charger Daytona 440 - auto - 4.10 Dana (now with 426 hemi)
'69 Charger 500 440 - 4speed - 3.54 Dana
'70 Road Runner 383 - 4speed - a/c (now with 440)
Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500465
05/25/18 09:38 PM
05/25/18 09:38 PM
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Posts: 5,687
Hamilton, Ontario Canada
Magnum Offline
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The right way is not have the entire electrical circuit passing through a gauge.


69 Super Bee, 93 Mustang LX, 04 Allure Super
Re: amp gauge: a right and wrong way [Re: Magnum] #2500472
05/25/18 09:55 PM
05/25/18 09:55 PM
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Posts: 8,650
Houston, Tx
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Originally Posted By Magnum
The right way is not have the entire electrical circuit passing through a gauge.


Understood... But the owner can't get the conversion system.... I have done it on pretty much all my cars over the last decade...


Troy
Houston Mopar Connection Club
'69 Charger Daytona 440 - auto - 4.10 Dana (now with 426 hemi)
'69 Charger 500 440 - 4speed - 3.54 Dana
'70 Road Runner 383 - 4speed - a/c (now with 440)
Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500476
05/25/18 10:16 PM
05/25/18 10:16 PM
Joined: Aug 2003
Posts: 8,650
Houston, Tx
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Well Hell..... There is a "RED" stamped in the printed circuit board.. I think I had them backwards..... Live and learn...


Troy
Houston Mopar Connection Club
'69 Charger Daytona 440 - auto - 4.10 Dana (now with 426 hemi)
'69 Charger 500 440 - 4speed - 3.54 Dana
'70 Road Runner 383 - 4speed - a/c (now with 440)
Re: amp gauge: a right and wrong way [Re: Magnum] #2500482
05/25/18 10:37 PM
05/25/18 10:37 PM
Joined: Feb 2010
Posts: 1,294
Phila. Pa.
Mattax Offline
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Originally Posted By Magnum
The right way is not have the entire electrical circuit passing through a gauge.
It doesn't. Only the battery circuit.

Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500483
05/25/18 10:42 PM
05/25/18 10:42 PM
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Phila. Pa.
Mattax Offline
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Originally Posted By hemi68charger
Well Hell..... There is a "RED" stamped in the printed circuit board.. I think I had them backwards..... Live and learn...
But if they were backward, all it would do is show current going in the wrong direction. In other words it would show charging the battery when it was discharging.

Definately a major short downstream of the link.
Fusible Link in Charging Systems with Ammeters
The advantage of the original layout is the one link protects everything from the battery grounding. This means the alternaotr output wire can be run to the distribution points without additional fusible links - which of course add resistance under high draw situations.




Re: amp gauge: a right and wrong way [Re: DAYCLONA] #2500488
05/25/18 10:52 PM
05/25/18 10:52 PM
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Phila. Pa.
Mattax Offline
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I would NOT use nylon for a washer. Nylon can soften when warmed and then the nut will be loose and the connection isn't secure. Resistance goes up and then there will be a problem at the connection.

Use a material that does not flow. A fiber washer is good, and there a plastics that are acceptable -best if thermosetting, but in any event not something to risk with a maybe OK. Something from an electical supply house should have the info needed.

Re: amp gauge: a right and wrong way [Re: Mattax] #2500496
05/25/18 11:03 PM
05/25/18 11:03 PM
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Posts: 34,757
Lincoln Nebraska
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RapidRobert Offline
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What Mattax said, you have a dead short somewhere (likely at the ammeter terminals to ground) & if you have the red/black wires/terminals on the wrong ammeter posts it will just read backwards (but no harm/no foul) on that issue anyhow.


live every 24 hour block of time like it's your last day on earth
Re: amp gauge: a right and wrong way [Re: RapidRobert] #2500524
05/26/18 12:31 AM
05/26/18 12:31 AM
Joined: Aug 2003
Posts: 8,650
Houston, Tx
hemi68charger Online content OP
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I found an extra original fusible link ( i'm glad I keep my old harnesses )... I replaced it, and with the instrument cluster removed, I joined the black and red amp gauge leads... Placed the positive back on the battery and no harm... Used my screw driver to test the starter relay and it worked just fine.... So, something is going on with the cluster.. I have a good insulator between the gauge and housing, so I'm not sure.. The gauge doesn't appear damaged.. It is a pretty simple design mechanically...


Troy
Houston Mopar Connection Club
'69 Charger Daytona 440 - auto - 4.10 Dana (now with 426 hemi)
'69 Charger 500 440 - 4speed - 3.54 Dana
'70 Road Runner 383 - 4speed - a/c (now with 440)
Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500535
05/26/18 01:49 AM
05/26/18 01:49 AM
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Lincoln Nebraska
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RapidRobert Offline
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I'd dig into the gauge when you can & find where it is dead shorted to the (ammeter) case.


live every 24 hour block of time like it's your last day on earth
Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500612
05/26/18 10:52 AM
05/26/18 10:52 AM
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Phila. Pa.
Mattax Offline
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From what has been described, if there was a short in the ammeter, there should be evidence. It should show signs of heat and smell of burnt metal and plastic. Shouldn't have to open it to determine if its OK.

I say this because the fusible link went fast, and it was enough current that even the body ground couldn't handle it. Of course if the body ground wasn't a great connection to begin with, then that does't means so much.

Some place the hot wire had pretty good contact with the body. That is, assuming the engine block connection direct to the battery negative was good.

Last edited by Mattax; 05/26/18 10:59 AM.
Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500619
05/26/18 11:05 AM
05/26/18 11:05 AM
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Phila. Pa.
Mattax Offline
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I know its PIA, but it would be well worthwhile removing the bulkhead disconnect and check the charging wire terminals, esperically at the crimps. If they show signs of overheating, repair depending on condition.

(also, if the foam seal is real crumbling, Detroit Muscle makes new ones)

Re: amp gauge: a right and wrong way [Re: Mattax] #2500641
05/26/18 12:00 PM
05/26/18 12:00 PM
Joined: Nov 2003
Posts: 34,757
Lincoln Nebraska
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RapidRobert Offline
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I would highly suggest doing Nachos bulkhead parallel bypass. You run in addition to the OE 2 main in/out wires/4 brass terminals, with 2 new wires seperately around the bulkhead/thru a new hole/grommet in the firewall, like exits that curve around a border crossing/keeping the OE bulkhead 4 brass terminal connection OR just drill out the 2 bulkhead cavities for those 2 wires & run/solder 2 new wires straight thru with no brass terminals (leave 6" of the 2 wires behind the rear bulkhead half so if you have to pull em apart in the future you can do so).


live every 24 hour block of time like it's your last day on earth
Re: amp gauge: a right and wrong way [Re: hemi68charger] #2500660
05/26/18 12:47 PM
05/26/18 12:47 PM
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S.E.Wisconsin
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Robert
Where does one find the info on "Nachos bulkhead parallel bypass",???.
Dave

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