XJ6 series 3 Alternator replacement


Apr 10, 2017
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The alternator might be still working but if it is giving a low voltage this will affect all the electrical system on a sensitive series 3. Mainly the Bosch / Lucas fuel injection system; it won't work properly if the voltage drops below 12V.

There is lack of info about the alternator's specs even in Jaguar repair manuals. I couldn't find the dimensions and pictures are different from 1 document to another.
Repairing the 45Amps original alternator is not feasible because you can find a new replacement 75Amps Motorola type online for about 60USd / 50 Eur, so get a new one and store the original just in case.

I suggest to replace it a repair shop because the car has to be lifted and replaced from underneath.
But you have to buy the correct replacement and assist your mechanic with the wiring.

1st How to identify the problem? simply push the gas pedal and hold the RPM at about 1500 (lights OFF, AC OFF, Radio Off, etc.) the battery gauge indicator should read above 13 Volts
Bad old alternator (800x589) 2.jpg

Location left side (exhaust side) under the AC compressor
Jaguar XJ6 series 3 Alternator (320x217).jpg

In my opinion an upgrade to a new 75Amps alternator is an excellent decision so I did it.
Advertised Jaguar alternators are soo expensive! just because people don't know what to buy so they trust the specialists and they pay 3 - 4 times the price.

It is a Motorola / Bosch type ALT 111 (full of them on ebay and they are fitted to many cars of 70s 80s 90s). But be careful there are 2 types: left-hand or right-hand body.
The pictures below are of the correct one:
S9 (274x320).jpg S12 (320x240).jpg S11 (320x240).jpg

Now the electrical bits. Connections as indicated in the below picture:
But be careful if the Battery / Alternator warning light in the dashboard is not connected or broken, then the alternator will not start charging at idle when you start the engine!! only it will start charging at around 2000RPM. Many mechanics don't know the warning light trick of these alternators!!!
Battery warning light.jpg
So make sure the Warning light turns ON when your key is in position 2, and it gets OFF as the moment your engine starts.

Not to forget! change the belt regardless of its condition!
This is how it looks with a new alternator :mrgreen:
Running cold(640x374).jpg
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Phil P

New member
Mar 4, 2021
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Very helpful post Rigajag. I recently bought a 1987 XJ6 (really a 1986) and have battery charging problems. Trying to check all that I can before replacing the alternator! Might be asking for help from you -- thanks for your post!