Hot Rod Forum banner

AMC tach, voltage meter and neutral saftey switch.

6K views 9 replies 3 participants last post by  docvette 
#1 ·
I’m just about finished getting my 74 Javelin back together. I am having a bit of trouble with tying up the loose ends of the wiring harness I installed. Specifically getting the Tach/Clock working, the Voltage meter hooked up and wiring in the neutral safety switch. The wiring harness industry caters to the big three and AMC mixed and matched from the big three making retrofitting an after-market harness a bit of a challenge.

The harness is set up for a tach. I have connected the tach wire to the coil but get no reading on the tach when I attach the wire inside the car. I’m not sure if the Tach is bad or I’m not doing something incorrect. Any idea how to test the tach and wire it if it is okay.

I have no idea how to hook up the voltage meter and there are not provisions in the harness to connect it. Any ideas on how to wire the original meter? It is not tied into the instrument cluster like most of the Big three. The meter has two posts I assume are positive and negative but I do not know where I should make the connections.

I’m also clueless on how to wire in the neutral safety switch. The car has a 727 tranny with the standard chrysler NS Switch attached to the tranny. I’m not sure how to wire in the relay into the ignition system and the NS Switch and get things to work. I do not have any way to test the old relay and would perfer to use a new relay. The tranny has a new neutral safely switch.
 
See less See more
#2 ·
Doc here, :pimp:

All three are pretty Simple installations..

The Tach will wire , RED to 12 volts FUSED, SWITCHED power. The BLACK Wire will go to a properly Bonded Ground. and the third Wire (usually Grey) will go to the - side of the coil..

To test it simply pull it and wire it to another car..If it registers , it's good to go.

The NSS switch, Locate it, then locate the "S" wire on the starter, back track that wire (if a kit, it will probably be a purple) as close to the switch as you can get..connect one side there, then connect the other side (going up to the ignition switch) to the other terminal.

Check your mechanical adjustment, and you should be good to go.

The Volt Meter is Very simple as well..just find ANY FUSED, SWITCHED , source of 12 volt power, and a properly bonded ground and connect..your done! That simple!

The Clock may be problematic upon itself..it may be properly hooked up but dirty inside, I'd check for power and ground at the clock first, and if good, consider a repair/cleaning or replacement.


Doc :pimp:
 
#4 ·
I will test the tach tomorrow and if it works hook it up.

I learned that my "Volt Meter" is actually an "Ampmeter". After doing some forum searches I have decided I will not wire the ampmeter up. I will make a phone call tomorrow and get a quote on converting the ampmeter into a volt meter. This will make for an easy installation and less worry on smoking any wires if something in the ampmeter goes bad on me.

Doc my tranny is an AMC version of a Chrysler 727 torqueflight. The Neutral Safety Switch is combined with the Back-up Light Switch and screws into the tranny. It has three terminals two of which are used for the back-up lights. The center terminal is used for the Neutral Safety Switch and was orginally wired through a relay. I am at a loss on how to wire it into my harness beings it is only 1 wire.
 
#5 ·
Looks like time has taken its toll on the tach and the clock. I am going to send them with the ampmeter and have them all redone at the same time. Thanks for the replies Doc.

I guess tomorrow I will tackle the rear end as I have put it off long enough and I cant get the dash finished up until I get the stuff I'm sending out back.
 
#6 ·
Javelin360 said:
Looks like time has taken its toll on the tach and the clock. I am going to send them with the ampmeter and have them all redone at the same time. Thanks for the replies Doc.

I guess tomorrow I will tackle the rear end as I have put it off long enough and I cant get the dash finished up until I get the stuff I'm sending out back.
Doc here, :pimp:

Bummer about the tach and Clock..

Hope it won't cost too much to restore!

If so..let me know..I have a few short cuts...


Doc :pimp:
 
#7 ·
Javelin360, there is an AMC TSM (Technical Service Manual -- what AMC called their factory manual) on-line at http://www.tocmp.com/manuals/AMC/1973/Service/index.html. That has the wiring diagram and how the tach is wired. I believe it's a different type of tach than the pretty much standard one Doc described. The wiring is different -- it's an induction type, I think, doesn't just wire to the coil like newer ones do. The 73 TSM will be fine for the 74 -- no major changes in wiring or anything between those years. You might want to download the files and put it on a CD for later reference. Everything but the AC section is there.
 
#8 ·
According to my 74 TSM for AMC the Javelin has a "Signal type tach" . The manual indicates Gremlins have "In-Line type tach" I do not know the difference between the tachs. The wiring diagrams do not show engine bay connections. They just show the under-dash connections. Since I do not have the original harness in the car a lot of the diagrams have no meaning any longer.

Does anyone know what an "Inline tach" is?

On another note I purchased an aftermarket volt meter and disassembled it. I mounted the face plate from my old amp meter on the new volt meter. It bolted right into the old location and other than the needle being a bit different you can't tell it isn't factory. Granted the face plate does not show volts, as long as the needle is indicating zero my system is working properly.

I also disassembled the clock and all it appears to need is a set of contacts cleaned up. I'll clean them up tomorrow and see if it functions.
 
#9 ·
Well the clock and tach are now functional.

I cleaned up the clocks contacts and ground strap and it is working. If it goes south on me later I will replace it with a quartz movement that a fellow AMCer made me aware of.

I decided to test the tach one last time but using all of the proper connections in the cluster and it now functions. Out of the cluster it wouldn't do anything. Apparently there is a ballast resistor in the cluster that must be inplace for the thing to function properly.

Now if I could just get the neutral safety hooked up I would be a happy man.
 
#10 ·
Javelin360 said:
Well the clock and tach are now functional.

Now if I could just get the neutral safety hooked up I would be a happy man.
Doc here, :pimp:

NSS is super easy to do..

Just locate it, (usually on the column) and be sure you have the correct set of contacts..(they usually include Back up lamps too) and run the "S" wire from the starter from it to the switch, cut it and attach on one terminal, then attach the other terminal to the other end of the cut wire..that's it!



TYPICAL GM NSS TYPE


Doc
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top