I suck at electrical for vehicles!

[rockaukum]

So, If that got your attention, you most certainly know I am in need of some help.
Thiokol 1202B-38 is the model that I recently received. The previous owner had installed new gauges but they do not work. Hour meter and volt meter work but not the tach, oil pressure, fuel gauge, and water temp gauge. Today a friend stopped by to lend a hand. He is a electrician (mainly household stuff). We confirmed on the fuel tank that there is resistance and it changes when we lift the float. No shorts in the wires to the tank but the gauge does not work. We did the same to the oil sending unit and it too checks out okay but the gauge does not work. We tried trouble shooting the tachometer with no luck there either.
Anyone have any suggestions on where to start, what to look for? When I pulled the instrument panel off, I found three wires not connected. One hot and two not. I have not traced them down yet (waiting for the arrival of a tracer on order). There is power to all gauges, the lights work in the gauges but I think they have a separate power supply form the light switch.
I know I can operate the cat as is but....
I'd rather have this thing dialed in prior to heading out and about.
Any help will be appreciated greatly!

Pics are of the tachometer gauge, back of the gauge and the module mounted on the wall behind the gauge panel that the tachometer wire go to.

 

[mkntrakes]

You have a mess! first you need to get rid of the sun box it was for old tack and wont work with new style tack. you also need to get rid of voltage drop old sw gauges run on 9 volt not 12 so they put a voltage drop on the back side of dash. you need to find someone that can rewire the whole thing as i see in one of the pictures you have a red white and black wire on the same post.

 

[NDPilot]

This is what my 1202ST looked like when I got it and after I cut a new panel and replaced gauges and wire. The system is fairly basic. I replaced the wiring color coded to match the service manual so it makes it much easier to follow or trouble shoot. I could probably provide some assistance but I would find it difficult via email or here. PM me when you get a minute.

 

[NDPilot]

As you can see, I satisfied the purist in me as well as did a little updating.

 

[vintagebike]

NDPilot…Do you still have the Thiokol W temp gauge? My 2100B might need that exact one. Steve in McCall

 

[NDPilot]

NDPilot…Do you still have the Thiokol W temp gauge? My 2100B might need that exact one. Steve in McCall

That gauge was hooked to the OC-12 temp. I am still hoping to reuse it for the coolant but haven't found the matching probe yet. I'll let you know if I give up 😉.

 

[rockaukum]

NDPilot. message sent to you.

mkntrakes: So Do I by pass the ignition module completely or do I need one that is compatible? If I need a replacement, do you have a suggestion that will work with these gauges?
I have tried to locate any information as to wiring this particular gauge and have been unsuccessful.
Thanks for the help and interest.
Rockaukum

 

[vintagebike]

There is a Stewart Warner 970 series tachometer now on eBay that will match the tach transmitter you have already installed.

 

[mkntrakes]

NDPilot. message sent to you.

mkntrakes: So Do I by pass the ignition module completely or do I need one that is compatible? If I need a replacement, do you have a suggestion that will work with these gauges?
I have tried to locate any information as to wiring this particular gauge and have been unsuccessful.
Thanks for the help and interest.
Rockaukum

 

[mkntrakes]

No you can remove tack box altogetherView attachment 144929

 

[rockaukum]

mkntracks, Thanks for the update. I tried to view the attachment but I get the oops message.
rockaukum

 

[mkntrakes]

 

[rockaukum]

Thank you for the diagram. I'll give that a go.
In the mean time, here is what I am encountering as I explore this machine.
While tracing some of the wires I found this group of three that went up between the windshield and were cut / tapped up at the top.
There were more wires cut behind the dash, so I traced them down and removed them. One went to the center most toggle switch on the lower portion of the dash panel. This switch did not activate anything before, so I disconnected it too. Any Ideas as to the original function of this toggle switch?
more excitement to come....
rockaukum

 

[andyv916]

I am guessing a roof mounted light or a dome light ?

 

[rockaukum]

I believe you are correct. There is a patch piece in the center front of the roof. Learning as I go...
On the tach issue, I removed the wires for the ignition module and rewired as per the diagram shown above. Fired up the engine and no movement in the tach! I put the test light on the gauge lite which showed power, them moved it to the 'S' terminal post. The test light glowed brightly and upon a closer inspection, it was pulsing. I'll take that to mean the signal is being transmitted to the gauge but the gauge must be fried.
Is there a way to test the other gauges? I pulled the lead from the oil sending unit and grounded it out to the motor block and no reaction on the gauge. Can I put 12 v to the gauge? with that show anything?
Again, many thanks for the help,
rockaukum