[jclarkpms]

I have an old sun tach model st-601 that came with the car. I can't find any info for wiring. It has 4 wires (white,black,and 2 red) It was wired as follows. White to the coil,black to power,one red to ground,and the other red is not hooked to anything. Anyone know what's what here? Thanks.

[kate`s67gto]

HMMMMMMMM i removed a sun tach and it was not wired that way.
It had 1 red wire 1 white wire 1 green wire 1 black wire

red went to ignition12v
white went to illumination circuit (gray)
green went to tach
black is ground.

Hope this helps

[jclarkpms]

I have seen green going to ignition ( I think) but I get the feeling this one is quite old. Perhaps early seventies. The white ran through wall towards coil but not hooked up.

[Keith Seymore]

Is it old enough that it uses a "sending unit" mounted underhood?

If so, I can check mine and see how it is wired.

K

[jclarkpms]

Keith,


Really not sure about a sending unit. The guy had an old mallory ignition,coil set up which I get rid of , back to stock now. All that ran to the motor was a white wire.

[Keith Seymore]

Originally Posted by jclarkpms

Keith,


Really not sure about a sending unit....

It's a funky box that looks like an old Lionel train transformer or something. Here's a (not very good) picture of one:



I'm guessing by your response that you probably don't have one. Based on that I'm going to step back and see if someone else might be able to help.

K

PS - here's a picture of my tach. Does yours look like this one?

[jclarkpms]

based on your photo (no box on mine) I would say your tach is older than mine. Funny thing I've looked all over the web and can't seem to find anything close to mine model st-601. Thanks for the input...........any others?

[Peter Serio]

Here are some old sheets:

[Peter Serio]

Older models used a separate black box out underneath the hood which had 2 batteries in it that you had to replace about once every 2-3 years or so. Later they did away with the box and they (Sun) were able to incorporate all of the electronics into the dial display unit that mounted on the dash or steering column inside the car. Typically you have a ground, a 12 volt "+" and a signal wire that ran out underneath the hood, typically this wire was attached to the negative side of the coil. You also had a night-time light with a supply 12 volts, lights on wire and a black ground wire.

[jclarkpms]

Thanks for your input Peter...is it possible that one wire from tach tied into the ignition wiring of the car? As I said black leads to 12v power,red to a ground,white under hood. The second red wire ends under my steering column. It is near a factory wire (pink next to pink/black) that was spliced. I think this pink,pink/black has to do with key,ignition?

[Peter Serio]

Typically black indicates a ground wire, red could indicate 12 volt "+" from the fuse block whenver the key is on the on or run position. White could be your nighttime light wire or the signal wire, can you post photos of the tach & the backside where the wires exit?

[jclarkpms]

In this case I think one of the reds is ground (see photo of the 4 wires. red,red,black,white. this is how previous owner had wires run.) The black runs to a toggle switch with power. When switch is on light on tach comes on. White go's to - of tach,red to ground (see photo of red attached at base of steering wheel) The other red is the question. I've enclosed a photo of wires at base of steering wheel. If you'll notice the pink wire was cut. I think that has to do with key/ignition and the red wire in question leads here. Does that sound correct? If so I would guess it leads to the key side of this pink wire? I searched my service manual and can not determine what the pink wire is.

[george kujanski]

Your red wires were installed by the PO so all bets are off on the wire colors. The only colors that mean anything are the original wires that are actually part of the tach.

George

[jclarkpms]

George,

Those are the actual 4 wires coming out of the unit. I can see them. Is it possible that one of them does tie into the pink wire coming down the steering column? (key on?) I really do think that 3 of the 4 are run correctly. The PO was very meticulous about all aftermarket gauges,stereo,switches,etc. Based on all other work he did I think this tach is close but for the mysterious red wire. I see you are the master at these type things. Any thoughts?

[george kujanski]

Can you remove the tach, take some pix of the wire entry, and best of all, if you can open the case and take pix of the inside circuitry, I can figure it out. Grounding red wires is not typical automotive practice, especially from Sun.

George

[jclarkpms]

George,

I can certinally do that. I am headed out of town this AM. I will post late Sunday....thanks very much


Jeff

["QUICK-SILVER"]

The cut pink wire in the turn signal harness probably went to the key in switch buzzer.

About the red ground and black to toggled hot deal. All that's doing is turning on the light. Wires reversed would make the light burn all the same but that doesn't mean their right.

[jclarkpms]

George,

Ok here we go. To hard to get a clear photo. I opened up the rear of tach. Each post is labled as follows 4 total. Ignition switch, trigger, ground neg.,lights. The wires are color coded as I previously described. It would appear all are connected correctly except for the red wire labled "ignition switch" I mentioned the pink wire under my steering column was cut and I suspect the ignition wire from tach taps into this? Not sure though if it was spliced into both ends of pink wire or leads to only one side. What are your thoughts?

[jclarkpms]

George,


Any thoughts on this one....still trying to figure this one out. Thanks!

[george kujanski]

Since the wires are labelled, connect them as labelled; don't worry about the color. As far as the pink wire, I don't know what it is, but you can find out. Get a multimeter, set to voltage function, and measure the voltag on the wire to ground with the key on and off. If you have 12V with the key on and zero with the key off, use that as the ignition switch connection. Otherwise find a ignition switch circuit and connect the tach there. Regardless, you should find out where the pink wire goes so you can either use it or tape it up for safety.

George