OXS Counter

My OXS Counter is making a noise that bugs me. I'm thinking this thing is run by a cable from the tranny. No info in Haynes. Is this run by a turning cable?

I was further thinking that the cable may not be separately available and I won't want to replace the unit. So then I thought, why not just disarm it?

It has a few electrical wires to it, at least one of which go to the speedo. I'm afraid of hurting speedos. I think this thing does not do much, and if the part is spendy, I'll be tempted to just cut the cable. I can live without the OXS warning light and I don't think this would hurt anything. Cheerful, non-political comments welcome.


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'83 SC

Okay, the dealership parts guy says this part (the square box with the reset button on the bulkhead behind the speedo) does not have a drive cable. If I believe this, then my unit makes a noise like a bad drive cable, but with out the drive cable. Does this make sense (or nonsense) to anyone?

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'83 SC

I'm no electronics guru, but I looked at the wiring diagram. The counter has a transistor in it that is fed by two wires from the speedo. My guess is that these two wires feed (flickering?) current that causes the mileage counter to count. Why not unplug one of these to see if the transistor is just noisy and your noise goes away. Wires are red/blue and white/red. I'd try either or both and see what happens. (And if that cures it then leave them unplugged permanently since there appears to be no connection with the OXS/fuel system --- see next paragraph)

I also don't see any reason why you can't also unplug the red wire (from the OXS light) as well and then you should have no possible current whatsoever going to this counter. It does not appear to have any affect on any other circuit except to turn the OXS warning light on. (Of course this would disable your OXS warning light, obviously. But who cares --- since, IMHO, this is mostly a gimmick to get you into the dealer to push the reset button) and then lead you down the dealer-will-do-some-maintenance-at-big-buck$ or other fixes. The owners manual does admit to the counter being there to turn on the light at 30k so you can go to the dealer (and I agree that it probably does this). The owners manual also says that if the OXS light comes on then it MIGHT indicate a malfunction in the OXS fuel monitoring system (my opinion is that this is bunk since I can't see ANYTHING in the circuitry that connects the OXS light to anything but the counter --- nothing from the OXS/fuel system)

So there you have it --- my non-professional dissertation guess on the counter and the OXS light.

P.S. the wiring diagram is for a 1982SC but I think it is identical to the 1983SC.

[This message has been edited by tog (edited 11-13-2000).]

[This message has been edited by tog (edited 11-13-2000).]

Super,

Terry is correct that the counter only drives the warning light, and serves no other useful purpose! It apparently uses a transistor circuit to drive Your Noise Source ... an electromechanical counter similar to an odometer, that triggers a switch that closes after 30,000 miles.

One solution would be to locate the counter, and wrap it in a box of R-19 pink fiberglass insulation and duct tape ... similar to the Lithium Hydroxide contraption the Apollo 13 Astronauts built of scrap materials to save themselves from rising CO2 levels ...

Another fix would be to disconnect the brown ground wire at terminal 31 on the mileage counter module from the ground common piggy-back at the oil pressure gauge. That should kill your ticking noise! Don't disconnect the Red/Blue wire and leave it dangling around uninsulated, as it is raw +12 Volts from the speedometer piggy-backed connection! The G terminal White/Red wire that supplies the drive pulses for the counter from the speedometer can be disconnected, but I would insulate it to keep from harming the speedometer. The worst thing that could happen would be for it to bump into some 'loose' +12 volt connector by accident!

I get the impression that the mileage counter module doesn't have quick-disconnect connectors, just wires coming out in a bundle ... did I read between the lines correctly, Super?

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Warren Hall
1973 911S Targa

Sorry, Tog and Warren, for loosing track of your previous advice here.

Warren, you're not the only one I've known with your level of car knowledge, but it sure is thrilling to read your assessments sometimes. You are correct in that the harness to the OXS counter is a multi plug or worse. I will locate the ground connection you suggested, and will ensure it is insulated and secured. I expect this will stop the noise.

Didn't the astronauts use dirty socks for that? You know, I wanted to build, and live in, a 'space capsule' while the astronouts went to the moon the first time. I was 13.

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'83 SC

Did your ticking start when you loaned your car to a "tomato"... you know, "Attack of the Killer Tomatoes"

(that pun was as bad as a Godzilla movie --- Jeez, I must be getting desperate and bored with this Killer weather here in Texas... I just got $800 worth of fixup parts from Pelican for my 911 and the weather went straight from Sahara Desert to frozen tundra and I can't get anything done !!! )

Texas Tundra huh Tog? I rebuilt my Harley in the dining room, but that was twenty years ago and my wife was in luv. I don't think the SC would fit through the doors anyway. Just a thought.

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Robert Stoll
83 SC
83 944