Racetech Speedometer Problems

[Guest red7]

I have a Racetech Speedometer wired to their Hall effect sender unit. I've wired it up according to the diagram but .....nothing. I've tried spinning a magnet past the sensor but.....nothing. Anybody got any ideas?

[Guest Ian & Carole]

NO

[Mitch]

buy a smiths one??

 

Mitch

[Guest allenr03]

Not sure passing the magnet accross the sensor head once would do anything anyway!!

 

Is the wiring definately right? Is the sensor head close enough to the magnets? Is the calibration set up correctly?

 

I bought a Smiths hall effect sensor with a built in LED so I knew it could see the propshaft bolts (I didn't use magnets.) I wired it uo following the instructions then when it wouldn't work checked what I'd done and I had wired it wrongly! Its easy to do.

 

Result is the speedo works perfectly and was bang on at SVA.

 

Rich

[Guest red7]

Thanks Richard. I'll try again tomorrow night. Have you got a link to the smiths sender? I can't find it.

[Guest allenr03]

http://www.merlinmotorsport.co.uk/INSTRUME...oduct_info.html

 

Its a Telemetrix (by Smiths) item. Doesn't need magnets but youcan use them if you prefer.

 

RICH

[Guest red7]

Frustrated. I've tried two experiments neither worked. Why?

Simulated sensor on car by the following method.

 

Experiment A

 

1/ Attached Hall effect Speedo sensor to the front fork of my upturned bike.

2/ Attached a strong magnet to a spoke. Magnet to sensor gap 1mm.

3/ Connected sensor to Speedo

4/ Switched on car ignition.

5/ Spun bike wheel.

Nothing registered on speedo.

 

Attached a multi-meter to the output from the sensor.

No volts.

I thought I'd have seen a pulse every time the magnet passed the sensor?

 

Experiment B

 

As above but reed switch in place of sensor and 9volt battery in series to make a pulse circuit.

Nothing.

 

Where do I go now?

[Guest red7]

Hi Mez,

Great to hear from you. Have you seen an actual speedo reading from the Racetech unit? I think the needle is welded to to zero pin on my unit! I thought I'd be able to measure an output voltage from my speedo but yet again nought. I did have a small success when I found my 9v battery can advance the mileage when a pulse is connected across the terminals. What stage of construction is you're car at?

 

Regards,

Steve

[Guest allenr03]

I nhave Telemetrix instruments and I'm sure there is an output voltage when the sensor head detects a ferrous object so I think it would be fair to expect a constant voltage if you held the sensor head next to bolts or something. Sound like the wiring is wrong or the speedo/sensor is faulty. My sensor has 3 wires, one to the speedo, one +ve supply and the earth but the colours weren't what you'd expect, the black was the speedo cable and I think the earth was brown or blue, can't remember. I know I wired it up wrongly at first!!

[Snapperpaul]

I have also been told that shielded cable, with the shielding earthed can also help.