Hi guys,
If anyone wants to fit an RPM Gauge to your Defender Puma (2.4 in my case) but I am betting it's the same for 2.2. Here is what I did.
I am fitting an EMS3 gauge which has RPM input also, so I figured why not use it.
Now with diesels you don't have a true straight forward way of detecting RPM, Unless you pick this up from a crank sensor I guess. The only way is to pickup from the rotational speed of the alternator. This is your only option, and I don't know anyone else doing it via crank sensor.
Apparently most of the older alternators have a W terminal on the back of them for the RPM Gauge. But not the Defender Puma 2.4 alternator, which is actually a Bosch alternator.
So to add this to any alternator you need to tap into one of the windings. Fortunately the Defender alternator makes this very, very, easy.
1. Disconnect you vehicle battery/batteries.
2. Take the positive off the back of alternator
3. Remove the plug fitting with two wires
4. Remove the screws that hold the black plastic cover and take cover off.
5. You will notice a black plastic device (regulator) BTW when an alternator starts to fail to charge 90% of time this just needs to be replaced.
6. Take eyelet terminal (see photos) and fly wire fit it behind the screw for the alternator winding.
Then you have yourself a W wire terminal for an RPM Gauge. In my case an EMS3, this gauge can then be calibrated to match the exact ECU reading of RPM that is taken from the crank sensor.
Hope it helps alot of people because I couldn't find the info anywhere on the interwebs.
All the best,
Damo
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