Thread: Disco alternator in a 300tdi Defender

I always replace the original defender 65A one with the Disco 100A one, too Ranga

JC

Originally Posted by justinc

I always replace the original defender 65A one with the Disco 100A one, too Ranga

JC

Yeh, but why?

100Amp vs 65A, and they are rebuildable IE the bearings are replaceable. The Defender units use the end of the rotor shaft as a bearing surface, which means when the rear needle roller bearing fails it takes the whole rotor with it, costing the same as a new alternator....At least bearings etc are cheap for the Disco version.
And they are 100Amp output, not 65Amp.

JC

Gents,
Bringing an old thread back to life - I'm in the process of swapping over my dead Defender ALT with a Disco 100amp one.
Now, on the Defender ALT there is the H/D cable wire for charging the batteries, etc and the only other wire (Yellow with brown strip)

The Disco 100amp ALT has 3 wires

• The H/D wire for charging batteries
• Yellow and Brown strip wire
• White with black strip wire

I've measured the volts on my other car (Disco Tdi) to check what voltages there are at the Disco ALT as follows

• Yellow and Brown strip wire - approx 7v when engine running at idle
• White with black strip wire - approx 13.5v when engine running at idle

My question is with this conversion - how do u wire the Disco ALT into the Defender when the Defender only has the H/D Charge wire + the Yellow/brown strip wires? What do I do with the 3rd Terminal where the White/Black strip is connected to on the Disco?

Also, with engine off on the Disco, the only wire with 12v is the H/D one, the other 2 wires a not alive with engine OFF & they are also not alive with the ignition ON, they are only alive when engine is running.....

Can anyone help us with some advice as to how to wire these Disco ALTs into a Defender?

Ok, being an auto elec I might be able to help. On the alternator the 3 wires are 1, 12v. 2, warning light or battery light. 3, tacho output. I will go and take a photo of the back of mine to help

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Hope this helps.

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The red wire is my tacho, brown with yellow is warning light, and the one with 3 cables is the main battery post.

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I did the same on my 97 Def. just ignore the tach wire