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Amp meter bypass help please #2670292
06/26/19 04:32 PM
06/26/19 04:32 PM
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Sonoran desert, Arizona, USA
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moparjo68 Offline OP
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I've studied the MAD electrical diagram for the amp bypass. I just wanted to make sure I'm reading the diagram correctly. This is for '68 Charger that I'm working on. So, according to the Mad diagram, the 12ga black wire coming from alternator is no longer going to bulk head connector, its being re-routed to the batt stud terminal on starter relay.

The 12ga black wire that was spliced off from alternator......thats going to welded splice and amp meter.......its also connected to batt stud terminal on starter relay. The 12ga black and 12ga red wire are spliced together that once went to amp meter, thus creating the bypass. The 12ga red wire coming from amp meter is also connected to batt stud terminal on starter relay. Am I reading this correctly? These wires are starting and ending at the batt stud terminal at starter relay? And the alternator is also going to batt stud terminal as well?

Last edited by moparjo68; 06/26/19 04:38 PM.
Re: Amp meter bypass help please [Re: moparjo68] #2670304
06/26/19 04:55 PM
06/26/19 04:55 PM
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Canuckville
68Cbarge Offline
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To keep it simple.
1. run a wire with fusible link from battery stud at starter relay through firewall and attach to positive side of ammeter gauge
2. run a wire with a fusible link from battery stud back of alternator to battery stud of starter relay.

DONE

Make sure the fusible links are at the starter relay making them accessable.
The ammeter gauge will work but now only carries 50% of the load which is a good thing.
Optional is run a voltmeter gauge for an accurate monitor of the charging system.

Also run an electronic voltage regulator for the charging system and electronic 5 volt limiter for the gauges.
Hope this helps


'68 Newport Custom Barge on a Budget!! BOAB
1973 Satellite WAGON! 318- 3 on the tree!!
2008 Chrysler 300c HEMI!
Re: Amp meter bypass help please [Re: 68Cbarge] #2670439
06/26/19 09:04 PM
06/26/19 09:04 PM
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Sonoran desert, Arizona, USA
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moparjo68 Offline OP
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I don't want to keep amp meter in circuit anymore. It had gotten hot sometime in its life and is now a "bit crusty". So I am bypassing the amp meter and removing it. I am putting in a volt meter.

Re: Amp meter bypass help please [Re: moparjo68] #2670462
06/26/19 09:47 PM
06/26/19 09:47 PM
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Frederick, MD
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71charger Offline
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What's not clear to me in the MAD Electrical diagram is why both the red and black wires need to be brought through the bulkhead. In their diagram, the lead from the alternator stud is disconnected from the bulkhead and rerouted to the starter relay. The black wire in the passenger compartment that connected to it is extended almost to the starter relay where it's spliced to the red wire and connected to the relay with a fusible link. The black and red wires formally attached to the ammeter are connected together.

Why not just connect the red wire from the starter relay that already has a fusible link to the black wire inside the passenger compartment that had been connected to the alternator. Then you could eliminate the red wire from the bulkhead to the back of the ammeter and not have to splice the red and black together at all. You could just tape off the black terminal that had been attached to the ammeter or use it for a voltmeter.

Last edited by 71charger; 06/26/19 09:48 PM.
Re: Amp meter bypass help please [Re: 71charger] #2670487
06/26/19 10:58 PM
06/26/19 10:58 PM
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Sonoran desert, Arizona, USA
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moparjo68 Offline OP
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Ok 71 Charger, if I were to hook up black/red wires precisely as you stated in your post, I don't think I would be making the "loop" as shown in MAD diagram. This is confusing.

Re: Amp meter bypass help please [Re: moparjo68] #2670573
06/27/19 09:40 AM
06/27/19 09:40 AM
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Frederick, MD
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71charger Offline
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The "loop" in the MAD diagram seems unnecessary. The circuit is completed through the chassis grounds. I was wondering if anyone can say why connecting the red from the fusible link to the bulkhead to the black from the welded splice, then eliminate the black from the fusible link to the bulkhead and the red from the old ammeter to the bulkhead would or wouldn't work and be simpler.

Re: Amp meter bypass help please [Re: 71charger] #2670774
06/27/19 04:13 PM
06/27/19 04:13 PM
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Ontario, Canada
RealWing Offline
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Connecting both the red and black through the bulkhead connector reduces the current through each bulkhead contact by half compared to just using the red through the connector. Reduces the circuit resistance and risk of overheating the connector.


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Re: Amp meter bypass help please [Re: RealWing] #2670797
06/27/19 05:25 PM
06/27/19 05:25 PM
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Sonoran desert, Arizona, USA
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moparjo68 Offline OP
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So............could I hear back from those who bypassed their amp meter using the MAD diagram and let me know if they have had any problems/issues or worst yet, melted wiring.

Re: Amp meter bypass help please [Re: moparjo68] #2670805
06/27/19 05:49 PM
06/27/19 05:49 PM
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Tucson, AZ
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cruzin Offline
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I followed the MAD amp meter bypass instructions on two cars and have not encountered any issues. Obviously, I do not have an operational amp gauge and did not supplement with a volt meter either.

Re: Amp meter bypass help please [Re: moparjo68] #2670807
06/27/19 05:56 PM
06/27/19 05:56 PM
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Sixpak Offline
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I think the ammeter gets a bum rap - if anything is the culprit for electrical issues it's the connections at the firewall bulkhead connectors. For a 'normal' current draw (anything close to stock) just keep those cleaned and greased . These ammeters may have changed design in later years, but every ammeter gauge I've worked with on an old 60's to mid 70's Mopar was basically two terminal studs connected to a strip of brass between them - effectively tying the black and red wires together. The ammeter needle moves like one in a compass, sensing the direction the current is flowing. Outside of the fiber/spacer/insulating washers on the terminal studs not installed properly or breaking and causing shorts, there's nothing to wear out or short out. You could bolt the red and black wire ends going to the ammeter studs together and insulate them, and you'll have removed the ammeter from the equation.
As far as any bypass wires, I run one 12 gauge wire from the stud on the alternator back to the starter relay + terminal. That's it. I leave the original black and red wires, with their terminals (male and female) at the bulkhead connectors cleaned and greased, in place, to feed juice to everything. That's providing something hasn't already melted; then of course some surgery is needed, but even then, I leave the wires going to the ammeter. Works for me - no issues.

Re: Amp meter bypass help please [Re: RealWing] #2670850
06/27/19 07:01 PM
06/27/19 07:01 PM
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Frederick, MD
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71charger Offline
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Originally Posted by RealWing
Connecting both the red and black through the bulkhead connector reduces the current through each bulkhead contact by half compared to just using the red through the connector. Reduces the circuit resistance and risk of overheating the connector.


I meant using just one wire through the bulkhead, but passing the wire directly through the bulkhead, eliminating the factory bulkhead connectors. In that case, shouldn't one wire from the starter relay into the passenger compartment be plenty? Especially given that everything's coming through a 16 ga. fusible link anyway.

Re: Amp meter bypass help please [Re: Sixpak] #2670954
06/28/19 12:01 AM
06/28/19 12:01 AM
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Sonoran desert, Arizona, USA
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moparjo68 Offline OP
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Quote: As far as any bypass wires, I run one 12 gauge wire from the stud on the alternator back to the starter relay + terminal. That's it. I leave the original black and red wires, with their terminals (male and female) at the bulkhead connectors cleaned and greased, in place, to feed juice to everything.

So...........the ONLY change you make to the wiring is what is mentioned above? What about the black wire that was already on back of alternator running to bulkhead connector? Do you keep it or remove it?

Re: Amp meter bypass help please [Re: moparjo68] #2670961
06/28/19 12:51 AM
06/28/19 12:51 AM
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Lincoln Nebraska
RapidRobert Offline
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I like my ammeter (+ a voltmeter on switched 12V) with the 2 bulkhead terminals drilled straight thru (per Nachos bulkhead parallel bypass). On your Q I would: delete the alt to bulkhead black wire. run the alt to the battery or starter relay (whichever is closer/convenient/practical). Then run from the starter relay to a FL at the bulkhead, then run this thru a single drilled out cavity in the bulkhead (same as Nachos bulkhead parallel bypass except you are only drilling one bulkhead cavity) inside to the one wire on the ammeter that goes out to the "welded splice" which'd be the one on the downstream ammeter terminal (I forget if it is red or black). this gives a straight shot from alt to battery and a straight shot from the battery (via starter relay) thru the firewall to the welded splice where it T's to the ign switch/headlight sw/horn/fuse box to power everything inside. #1 #1 check/clean ALL terminals/connections including ground paths. EDIT & actually there ain't an issue say for aesthetics (appearances) with keeping the black wire from the alt into the ammeter terminal (if you do the rest of the described bypass), just make sure you run this wire straight thru the bulkhead (nachos bypass) like the one with the FL as opposed to the OE 1/4" packard 56 male/female terminals makeing the bulkhead connection.

Last edited by RapidRobert; 06/28/19 07:53 AM.

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Re: Amp meter bypass help please [Re: RapidRobert] #2671030
06/28/19 09:59 AM
06/28/19 09:59 AM
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Canuckville
68Cbarge Offline
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I give up..The OP just does not get it.


'68 Newport Custom Barge on a Budget!! BOAB
1973 Satellite WAGON! 318- 3 on the tree!!
2008 Chrysler 300c HEMI!
Re: Amp meter bypass help please [Re: moparjo68] #2671039
06/28/19 10:09 AM
06/28/19 10:09 AM
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W. Kentucky
justinp61 Offline
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Originally Posted by moparjo68
Quote: As far as any bypass wires, I run one 12 gauge wire from the stud on the alternator back to the starter relay + terminal. That's it. I leave the original black and red wires, with their terminals (male and female) at the bulkhead connectors cleaned and greased, in place, to feed juice to everything.

So...........the ONLY change you make to the wiring is what is mentioned above? What about the black wire that was already on back of alternator running to bulkhead connector? Do you keep it or remove it?


I did the same thing, only difference is that I used a #6 wire. Also I left the factory wires alone, including the black wire on the alternator.

Re: Amp meter bypass help please [Re: justinp61] #2671105
06/28/19 12:11 PM
06/28/19 12:11 PM
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north of coder
moparx Offline
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Originally Posted by justinp61
Originally Posted by moparjo68
Quote: As far as any bypass wires, I run one 12 gauge wire from the stud on the alternator back to the starter relay + terminal. That's it. I leave the original black and red wires, with their terminals (male and female) at the bulkhead connectors cleaned and greased, in place, to feed juice to everything.

So...........the ONLY change you make to the wiring is what is mentioned above? What about the black wire that was already on back of alternator running to bulkhead connector? Do you keep it or remove it?


I did the same thing, only difference is that I used a #6 wire. Also I left the factory wires alone, including the black wire on the alternator.


i did the same, only used a #8 wire. i will be upgrading the engine in my charger, as well as installing a denso 90amp alternator, ac, electric fans, and an electric fuel pump.
at that time, i will be upgrading my underhood wiring as well. will go with a #6 [or possibly a #4] wire then.
beer

Re: Amp meter bypass help please [Re: moparx] #2671237
06/28/19 05:22 PM
06/28/19 05:22 PM
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When I sell my wire around cables, which includes a fusible link, I suggest leaving all the OEM wiring in place if the bulkhead is in good shape.

I'm not a fan of ammeters and bypass/take them out of the system. I run a voltmeter instead. Want to run an ammeter, have at it.

8 gauge wire, which is the smallest wire that I sell. Hides really easy in the OEM harness tabs

[Linked Image]


Last edited by crackedback; 06/28/19 05:23 PM.






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