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510 Tach. wiring

Posted: 07 Oct 2009 11:37
by tlap
Well I posted on the other site about this, but thought that I would try here also.
I have a tachometer for a 510 that has had the wires modified. I am not sure as to which color wire goes where.
I have searched and searched and come up with some very good information about wiring a 510 tach.
I have the DQ article which talkes about modifying one also. This article states that there were two different tachs, a 3 wire and a 4 wire. Mine is the three wire. Here is a picture of what the (incorrect color) wires look like soldered to the circuit board.
If someone has a tach that they can take a picture of the wire colors on the circuit board, it would be really apreciated.
Image

Re: 510 Tach. wiring

Posted: 07 Oct 2009 13:48
by Dimebag
Can you post a pic of the front face for clarification?

Re: 510 Tach. wiring

Posted: 07 Oct 2009 15:58
by tlap
Here is the front.
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With the help of quick510, I think that we have determined that this tach has had the circuit board replaced with a 200SX board.
So now, would someone have a 200SX tach laying around to compare?

Re: 510 Tach. wiring

Posted: 07 Oct 2009 16:36
by qwik510
I know you don't want to guess but taking a look at the wires, one is 12v+, one is 12v-, and one goes to the negative side of the coil.

I don't think you will do any harm if you try to hook it up. If it was me, I would hook up the red to 12v+ and then try the other two in both combinations. Hook up some long wires to each wire and test it from under the hood. My guess is that Black/green is the one to the coil.

Re: 510 Tach. wiring

Posted: 07 Oct 2009 16:48
by tlap
I am leaning that way too, it makes sense that red=+12V, blk/wht=-12V, and blk/grn=coil. If I cant dig up any info on a 200SX tach, I will have no other choice but try it.
Thanks for your help.

Re: 510 Tach. wiring

Posted: 07 Oct 2009 17:12
by qwik510
tlap wrote:I am leaning that way too, it makes sense that red=+12V, blk/wht=-12V, and blk/grn=coil. If I cant dig up any info on a 200SX tach, I will have no other choice but try it.
Thanks for your help.

Seems like that green wire on terminal #3 could be a ground. If it is, maybe trace it to see if the blk/white or the blk/grn cross it anywhere. Then you will know which one is the ground and the other one will be to the coil.

Re: 510 Tach. wiring

Posted: 07 Oct 2009 17:54
by tlap
OK, the green wire trace crosses the red wire? Could it be they used a red wire for ground??
Image
Image
(I will clean up those ugly solder joints too.)

Re: 510 Tach. wiring

Posted: 07 Oct 2009 17:58
by qwik510
Looking at those solder connections, it looks like those terminals were resoldered. I would not trust the colors of the wires that were used to determine what goes to what.

Where does the other end of the green wire go to?

Re: 510 Tach. wiring

Posted: 07 Oct 2009 18:03
by qwik510
Looks like the blk/white doesn't connect to any other parts of the circuit and the blk/grn only goes to one other. The red goes to several of them.

I know if is no help but I was just pointing it out.

Where did you get the tach and did the PO tell you anything about it?

Re: 510 Tach. wiring

Posted: 07 Oct 2009 18:34
by tlap
I know, the solder joints are terrible. The PO never had it installed in anything either.
Those solder joints are what made me realize that the wires were changed at some point.
The green wire goes here, to one side of the coil spring
Image

Re: 510 Tach. wiring

Posted: 07 Oct 2009 19:18
by qwik510
Sorry. No help here. I would try it like we said above. If it doesn't work, go to the JY and get another tach to use the guts from and start over following the DQ article.

You have the most important parts. The stock tach housing and the face. :mrgreen:

Re: 510 Tach. wiring

Posted: 11 Oct 2009 19:04
by tlap
So, quick510. A little update for you.
I discovered that on the circuit board terminal #1 is to coil- (through a balast resistor), #2 to +12v, and #5 goes to ground.
I got it all connected and adjusted the variable resistor to match an external tach at 3000RPM.
I have read on one of these forums that the automatic wagon does not have the 3 prong connector wrapped in blue tape in the factory harness. My wagon was a 4 speed car and it does have this 3 prong connector, it must be the same harness as the sedans?
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Here it is in the car
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Thanks so much for your input.

Re: 510 Tach. wiring

Posted: 11 Oct 2009 19:17
by qwik510
Glad to hear you got it working. Sounds like our guess was right.

Congrats :mrgreen:

Re: 510 Tach. wiring

Posted: 11 Oct 2009 23:21
by Byron510
tlap wrote: I have read on one of these forums that the automatic wagon does not have the 3 prong connector wrapped in blue tape in the factory harness. My wagon was a 4 speed car and it does have this 3 prong connector, it must be the same harness as the sedans?
To my knowledge, all sedans and wagons (70-73) that I have worked on have had the connector taped up with blue tape just to the right of where the tach/clock will mount. I've never seen a 70-73 harness without this plug in place.
Byron