E 30 electronic speedo

healeyneil · Post by **healeyneil** » Mon May 16, 2016 9:43 pm

Does anyone know what sort of signal the sender for one of these should transmit ? My adapted speedo isnt working. I put a trigger wheel on one driveshaft and mounted the sender to suit, but no joy, so my first thought is to put a voltmeter on the signal wire. Any thoughts ?
Thanks, Neil

BertjeConti · Post by **BertjeConti** » Tue May 17, 2016 9:01 pm

You'll need a square wave signal from the sender unit, the sender unit needs to have a open collector or open drain output to ground. about 9 pulses per wheel turn.

Hope this helps

healeyneil · Post by **healeyneil** » Wed May 18, 2016 7:36 pm

Ah well, thats me stuffed then ! I can just about run checks with a voltmeter !

BertjeConti · Post by **BertjeConti** » Wed May 18, 2016 8:30 pm

healeyneil wrote:Ah well, thats me stuffed then ! I can just about run checks with a voltmeter !

What kind of pulsesender and triggerwheel have you tried?

healeyneil · Post by **healeyneil** » Wed May 18, 2016 11:33 pm

The sender is an E30 one removed from a diff, and the trigger wheel I made myself, copied from the dimensions of an original. I think I need to review my wiring !

BertjeConti · Post by **BertjeConti** » Thu May 19, 2016 7:54 am

healeyneil wrote:The sender is an E30 one removed from a diff, and the trigger wheel I made myself, copied from the dimensions of an original. I think I need to review my wiring !

did some googling:
Okay, that sensor type is fairly simple, in fact it is nothing more than a switch. one leg in the sensor contains a magnet and the other leg a reedcontact, which is a switch operated by magnetism.

So you could first test the sensor with your multimeter. Put the multimeter in Resistance, and hook up to the sensor. while turning the triggerwheel slowly, the resistance should swap from zero to infinite and back. If it is realy silent you should be able to hear the sensor switching. A reedcontact makes a very soft clicking sound when operated.

If sensor ok then check your wiring to the dash.

good luck.

healeyneil · Post by **healeyneil** » Thu May 19, 2016 9:02 am

I will do that at the weekend. Many thanks, Neil

Duracel79 · Post by **Duracel79** » Thu May 19, 2016 12:31 pm

Have you got power and earth to the speedo itself as well as the signal wire?

My E24 electronic speedo needed:
1 - 12v power
2 - Earth
3 - signal wire to the sensor, then the other side of the sensor goes to earth.

Hope this helps

Ben

healeyneil · Post by **healeyneil** » Mon May 23, 2016 1:24 pm

Tests done , and it looks like my sender is dead. Thanks for the suggestions
Neil

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E 30 electronic speedo

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