[klunker]

Anyone have a wiring harness schematic for a 65 rally gage harness?
Also I assume that the standard larger main dash harness is different, is that true?
I have a 65 with factory rally gages and the larger main harness has the temp gage idiot light in it. I assume it does not function.
In both harnesses there are alot of wires that are not used, I would like to know that I am wiring it up right. I pulled the dash out to clean it up. And on top of that there was some melted wires (pink power leads) that needed replacing/repair. Now I am trying to get this back together.
Thanks
Dirk

[Peter Serio]

For 1965 (which was the very first year) of the option of rally gauges in the dash on Lemans and GTO. The main harness (it's the one with the fuse block) was the same as used on a regular dash.

When someone ordered rally gauges the factory used an additional jumper harness which "piggybacked" alongside the main harness to give you extra wires for the plug-ins for your tach, oil pressure and coolant temperature gauge(s). There are also wires for 12 volts "+" power and gray wires; lights (the 4th pod) and ground.

This leaves you with 2 bulb sockets left over (one for oil and one for temperature light) that are no longer needed. You also end up with an extra green and a blue wires out underneath the hood. This has been a question for years as to what, the factory actually did with these "leftover" wires. In the old newsletters of a small magazine called "Classic GTO" this was covered in an issue.

Underneath the hood, the green wire and the blue wire were simply clipped at the point they protruded out of their black tape wrap; (these are NOT live wires at this point). I can't remember off the top of my head what was done with the bulb sockets. Those may have been clipped also, or just folded back along the harness and taped. I do not think those 2 would have had any bulbs in them.


I someone needs I can post as a jpeg a block diagram of the jumper harness. NOTE: This diagram is also included as your instructions whenever you buy a repo jumper harness from M&H. Just ask.

[klunker]

I would like a schematic of the Rally gage harness, there a about 1/2 dozen connectors that are unused in my harness. Including a bunch of brown wires which is the same color as the tach wire. The reason I want to be sure is my tach also does not work. I checked the fuse in the holder next to the coil first, it was fried. So I replaced it. The 2nd one fried also. I looked into the harness under the dash thats when I spotted alot of melted insulation on the pink wires. I replace/reworked all these and I would like to be sure everything is hitched up right so I don't fry more wires and it can help me chase down any possible errors from previous owners. Altho the car appears to be very original you never know.
Thanks for your post Peter, it helps some. Also Tempests also came with rally gages, just for your info. And both the temp and oil press. idiot lights are in the main harness, sockets and bulbs and all. They are just hanging loose as far as I can tell.

[Peter Serio]

If it were my car I would replace everything as a harness that contains melted wires. Unless you are an electrical engineer and can build your own harness from scratch and from memory. Running 45 year old melted wiring it just asking for trouble. No car wiring harness was ever intended to last for 45 years. I would also identify and correct whatever it was that shorted out and caused the wires to melt in the first place! We are lucky as M&H makes all the wiring for these old cars now.


All main harnesses have at least one extra brown wire in them, it is for an accessory option such as a power antenna. Most of the time on a low or no option car it never even gets used. This brown wire has nothing at all to do with the tach. (If you have a TI ignition system there is a separate 12 volt brown wire taped INSIDE of the rally gauge jumper harness that runs off of the fuse box thru an in-line glass fuse to feed the switched side of the tach. The brown assessory wire off of the main can easily be spotted as it has a red plug on the end. The 12 volt fused tach feed wire (not used on cars with points ignition) has a black plug on both ends. These brown wires are live 12 volts whenever the key is in the on position.

In my experience most of our cars used a tan wire for the tach. It appears that the repo harness uses a brown wire underneath the dash for the tach, the ends are different though. On a points tach the brass metal tab on the back has a tag formed into it. The plastic plug that fits it has a slot; this is the wire that runs out to the "-" side of your coil. The other brown wire does not have a slot in the plug and the brass for it is perfectly flat. (TI tach only.)


The first photo is the instructions that came with a new M&H harness I bought. To me it was somewhat difficult to read so I made my own on a piece of notebook paper, just the basics for a car with a Points distributor.

[klunker]

Thanks for the pictures Peter.
I still have no clue what's up with my Tach.
It will blow the in-line fuse right away.
I thought I'd check and see if something is amiss in the rally gage harness and bypass it.
So I ran a wire from the negative post of the coil to the terminal on the back of the coil.
Same as your drawing. The cranked and cranked and would not start. I thought what the hell. The only thing I did was hitch up the tach wire as per drawing. I removed the wire and the car started right up. Then as it was running I touched the wire from the tach to the negative terminal of the coil and the car died.
Does this indicate that my tach is FUBAR?
I checked my harness for continuity from the coil to the tach with a good inline fuse and it showed continuity.

I understand what your saying about old wire harnesses. I have built my own harnesses already. I built the complete harness for a car that was fuel injected. That was easier than you might think. I used all GM weatherpack terminals. Its not hard, factits easier than the older stuff with the packard terminals. I have all the terminals, I solder and shrink wrap all my terminals and connections. If I have a wiring schematic its not a problem. Thats why I was asking for the schematic.

I guess I could go thru and buy all new wiring harnesses and put them in. However as a kind of do-it-myself kind of guy I'd like to fix it.

As far as finding the cause of the melted wires, you may never be able to find it. It might of been caused by some clown doing something stupid and screwing it up and "butchering" it back together to get it running and maybe he screwed the tach up in the process. All I can do is go thru the harness and replace the bad wires and make sure all is as should be. I have had this running again and no melting of wires so I don't know if I fixed up the problem or not. But I know it works. The tach still does not work. However if my test with a new wire right from the coil to the gage caused the car to not run I think the tach is bad.
I might have an extra rally tach laying around and if so I'll find out if that one works.

Any suggestions on what to do now?
Thanks

[Peter Serio]

You tach is either bad or someone has had it out in the past & left out one or both of the red nylon insulators that insulate the longest stud. Tachs do go bad from age and use. I can EM you direct bigger photos of the diagrams but I can't post them here (file size). If you need larger diagrams I would need you to EM me thru PYs member to member feature with your EM address.

Pete

[klunker]

Thanks Peter, I'll pull the tach out tomorrow and give it a close inspection.
I noticed on your pictures it references notes. where are the notes?
Thanks Again
Dirk

[Peter Serio]

Note #1 I do not have it but I have read it before.


I recall that references the 2nd brown wire which is the 12 volt "+" feed if you have a transistorized ignition option car only; which yours is points. So that brown wire (both ends) simply get folded and taped back along the harness. Not used.


The reason they put it in there is so they will not have to make and stock 2 separate jumpers. One for 95% of the car(s) which came with points and the %5 of cars with the TI option. Basically one stock # fits all 65s with rally gauges. M&H makes thousands of wiring harnesses so I suppose it is easier for them to give away one free wire and one in-line fuse holder per jumper than to stock 1,001 on their shelves.

[geeteeohguy]

Thanks for posting the diagram, Peter. I've owned my '65 with rally gauges sonce 1982, and it has always had a mechanical SW oil guage and an electrical SW temp gauge under the dash. I got tired of this, and today, after 28 years, decided to hook up the factory temp guage. I found where the previous owner cut the pink power wire and the green temp. wire. Thankfully, he didn't butcher the factory terminal...it was still hooked up to the gauge. So, I spliced the wires back together, pink to pink, and green to green, and now, both gauges peg as soon as they get power. The grounds look okay, but I will check further. Any ideas? Bad ground?

[Peter Serio]

If you could remove and mail me your 4th pod I would be happy to test both for you. The pod needs to be grounded.

I always run a separate ground wire to both housings behind the dash just to be safe.

Pink wire(s) 12 volts "+" (key on); green wire: back of gauge to temp sender. Blue wire: back of gauge to oil pressure sender. NEVER, ever apply power and ground to gauges with "sender" branch of the wiring disconnected. This puts the coils into a bind and car ruin an old gauge in a very short time.

[geeteeohguy]

Thanks again, Peter. I appreciate it. I will be in touch. Can I pull the 4th pod without disturbing the tach/speedo/gasoline pods?? If so, that would be much better, as I wouldn't have to take the car out of service.

[geeteeohguy]

I cleaned the tangs on the back of the temp gauge and it's now working. For how long, that remains to be seen! I will leave the oil pressure gauge disconnected until I get the proper sending unit to connect it. If I have further issues, I'll pull the unit and ship it to you for repair. Thanks again, Peter. You've been a tremendous help, especially with your wiring diagram which enabled me to verify my wiring.
Jeff

[Peter Serio]

Yes it is easy, just follow the directions on the shop manual for clock removal. You do not have to take the entire dash bezel out unless you want to. I would first remove the radio, the ash-tray and the ash-tray receiver bracket/ slide. Just to make things easier and give you a little breathing room underneath there.

Originally Posted by geeteeohguy

Thanks again, Peter. I appreciate it. I will be in touch. Can I pull the 4th pod without disturbing the tach/speedo/gasoline pods?? If so, that would be much better, as I wouldn't have to take the car out of service.

[geeteeohguy]

Still working today...drove the car to work. I ordered a sending unit from Lectric Limited. (gauge reads a little higher than actual temp). If it goes haywire, I'll pull the pod and send it to you. I installed an additional ground to the cluster because my gauge read higher when I turned on the headlamps....the ground fixed that. Thanks again for your time, Peter---you've been a lot of help!!
Jeff

[Ken K]

Backside.

[Peter Serio]

The plug-in terms. for your temp gauge are way out of wack! Actually you have them reversed. It should look more like this:

[Ken K]

Thanks, I will fix them.