Speedo problems STILL, NEED help!

[davis911s]

I AM REALLY CONFUSED

Ok my speedo still isn't working I just installed another speedometer sensor that I know is good. Still nothing working!

I tried reversing the wires where the sensor attaches to the harness in the car. Both the wires are brown with red stripes.

I also tried to hook up my multimeter to hear the beeps as I rotated the rear right wheel, there is nothing. I know this is saying that the sensor isn't working but, I know its good.

Could the multimeter be hooked up wrong? 2 wires, and 2 connectors for the multimeter, so I doubt that. I hooked it up as I would check for continuity.

THE PART THAT REALLY CONFUSES ME IS THE SENSOR IS A ROUND PLUG WITH 2 HOLES, ON THE TRANSMISSION THE IS JUST A RECESSED HOLE IN THE SIDE IF THE CASE, AM I MISSING A PART, THAT GOES IN THE HOLE AND "PLUGS" INTO THE SENSOR?

The speedometer has not worked since I put the engine back in the car in May. Neother has the Tach, but they cannot be related. The other gauges work.

Any ideas?

Shawn

[This message has been edited by davis911s (edited 09-01-2001).]

[Formerly Steve Wilkinson]

Shawn, you and I seem to live in parallel universes--same speedo problem. But first, I can advise that the only way to test the sensor for continuity is to put a fairly strong magnet on it before you hook the multimeter to the two wires. There's a tiny reed switch inside the sensor that has to close, as the magnet on the ring gear (or is it the pinion?) passes by it. When the reed switch closes, you'll get the continuity signal. There are other ways to test the sensor, but this is the one I learned (from this bulletin board), after replacing the sensor not once but twice.

Stephan

[davis911s]

Thanks Stephan

I checked the swithes with the magnet and they work. So I am thinking that the swith isn't far enough into the housing? But I doubt it because it is in tight. I will try tapping it in with a rubber mallet.

Shawn

[psychotron]

are you sure that the wires are hooked up right on the back of the speedo? i made that mistake myself once after removing the motor.

paul

[davis911s]

Paul

Thanks for the reply but I never detached the wires from the rear of the gauge? I think it is between the sensor and the housing, see my new post on this

Shawn

[john walker's workshop]

check for a poor wire a splice in the inspection plate area. they often get pulled apart during trans removal, when someone forgets to unhook them. did you check continuity of both wires from the sensor plug to the speedo?

[davis911s]

Thanks John

The slices look good, the problem is there is no beeps from the connectors.

If the sensor is unhooked and I attach a magnet it'll beep. When it is attached to the transmission and i rotate the rear right tire (left one held) there is no beeps.

So it must be between the transmission and the plug?

Shawn

[Formerly Steve Wilkinson]

Shawn, I feel your pain, as what's-his-name said. I've done everything you have and am having the identical problem, identical car. I'm back-and-forthing with Hartmut Behrens at North Hollywood Speedo, who has had my unit twice now for repair. Wire continuity checks. Sensor checks good. Speedo is assumedly good, since NH Speedo has gone through it. It's getting 12 volts. Wiring is correct to the back of the speedo. Nothing is broken, ripped, neglected, discontinuous...

One thing I checked, and from which I got a--to me--strange result is that I turned on the ignition, 12 volts to the speedo, and I disconnected all those brown (plus one brown/red) leads from the ground terminal. I then bridged the gap between that negative terminal and the ground wires with a multimeter, expecting to read 12 volts there, and instead got 2.64 volts. Same thing happened when I touched the negative lead of the multimeter from the speedo to a known-good (bare metal)spot on the frame: 2.64 volts.

Try this and let me know what happens. I've queried Behrens about it and will let you know if it is an anomaly.

Stephan

[john walker's workshop]

i've seem all the magnets come out of the sensor disc inside the diff housing.

[davis911s]

Thanks again everyone,

Stephan- how did yours die? Mine worked perfect until I took the engine and tranny out then nothing. I will try your wires too Stephan and let you know.

John Walker- do you think that is the problem with mine- the magnets coming off? Does this seem to make sense? The sensor works until I attach it.

There is NOTHING bettween the sensor and the access hole in the tranny is there? I feel like this is something small and causing big problems.

Its weird that it is this and my speedo at same time and NO correlation.

I wish I had a view of the parts diagram!

Shawn

[Formerly Steve Wilkinson]

Mine worked during the two or three miles I drove the car before buying it as a project--that's all I needed to drive it, since I knew I was going to totally rebuild it anyway--and then didn't work ever again after I put the toally rebuilt engine and partially rebuilt transmission (everything forward of the diff)back in the car. If John is right and the sensors can come off, I guess I'll find them on the drain plug when I change the gearbox oil as soon as my new bottle of Swepco arrives...

Stephan

[john walker's workshop]

being the sensor "triggers" are magnets, they can stick to a lot of things before they get down to the drain plug. it's a long shot, but i've seen it several times. no, there's nothing between the sensor hole and the inside trigger disc. the two wires can be hooked up either way.

[davis911s]

John Walker- is there any way to check for this (magnets gone) other than taking apart the transmission?

Shawn

[davis911s]

Stephan as I emailed you, I do NOT get that reading when I do that test. Mine reads 0.

So that is probably your problem, I am thinking mine is the magnets coming off. Does anyone know a test for this without ripping apart my transmission?

What if I put another magnet in the spot where the sensor goes? In theory if the magnets are still there it would push mine away, or push the ones inside away (BAD).

Anyone? This sucks No speedo or Tach.

Shawn

[john walker's workshop]

not much you can do to see them except pull the diff out. you could have it out in 1/2 hour though, then you would know one way or the other. pull the inner CVs off the flanges, pull the flanges, pull the side cover and pull out the diff. try the drainplug magnet. there may be one on it at least. this doesn't happen a lot, but it happens. when the drainplug is out, try shining a flashlight in there. you might be able to see the sensor disc and magnets as you turn the axle. just a thought. a real bright pocket maglight.

[davis911s]

Thanks John Walker

Maybe I will try that this winter when I have the engine out to replace the seals.

Thats only 6 weeks away for me

It sounds quite easy, knock on wood.

Shawn