XJ6 Series 3 Alternator Voltage Regulator Replacement Done Easier

The alternator should be holding a steady voltage all the way from idle to max revs at 14 volts for an XJ6 Series 3.

Low voltage could be a number of faults but if going from 15 volts to 18+ volts with headlights getting brighter, this would most likely be a defective voltage regulator inside the back of the Alternator.

The original voltage regulator was a Lucas 15TR 37666A with three wires found in the back of the alternator Lucas A133-75 24101D. The newer replacement voltage regulator part 15TR 37666D only has two wires. Article by Lucas confirmed the change to a two-wire voltage regulator where the red wire is now built into the unit and it is therefore no longer needed.

I just replaced the regulator inside the alternator in my 1983 XJ6 4.2L Series 3. I was having intermittent 17.5V bursts that would last for a few minutes which would cause my headlights to become very bright and then return to normal when the voltage went back down to 14 volts. Even after cleaning all the old ground connections and still having 17.5V spikes, I purchased a brand new, name brand voltage regulator.

If you don’t want to remove the alternator completely by removing one end of the sway bar and loosening the further end to move it aside a few inches to allow for removal of the alternator, you can install a new voltage regulator into the alternator while on the car after just removing the adjustable trunnion, using a cable tie to secure the alternator out of the way, removing the two alternator mounting bolts, flipping the alternator around and removing the back plastic cover and then removing and installing the new voltage regulator while the alternator rests on the sway bar and then reinstalling. I have been driving the car now for a month and no problems thus so far, voltage holds steady at 14 volts.

Tools needed:

To remove alternator from brackets:

Two 2 ½” wrenches

Two 9/16” wrenches

Two 7/16” wrenches

To remove the back plastic back from alternator and remove a few other small bolts holding wire connectors, etc.:

8mm socket

10mm socket

3/16” socket

5/16” socket

1/2” socket

7/32” socket

The Alternator pivots on two 5/16” bolts with bolt heads and nuts that are ½”. These are a little tricky to remove so to simplify my suggestion is to purchase of a 5 inch long bolt (5” long bolt with ½” head and ½” nut both 24 count fine threads). The bolt shaft can be smooth but threads need to be 4 1/4” from inside of bolt head to the start of the threads. I bought the bolt at an ACE Hardware store. Put the bolt in so the nut is on the front of the car side. This will simplify the removal and install of the alternator for the future.





Alternator before starting repair work from undercar view:

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Picture of alternator off of the belt tightener tensioner and pushed to the side and held by a cable tie, so now you can see to remove the two bolts on top that hold up the alternator.

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Picture of one bolt removed on the left, the right bolt nut off and ready to remove the bolt to drop the alternator and carefully flip it to show the back plastic cover for access to remove the back cover.

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Picture of back plastic cover on alternator with alternator resting on the sway bar. This is an original Lucas alternator.

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The wire ends that are held onto the alternator via small bolts now removed.

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Picture with black plastic cover removed and you can see the original voltage regulator with yellow, black and red wires. Remove the one small bolt on the right next to the red wire and it will pull out once you also remove the yellow, black and red wires.

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When you remove the yellow wire small bolt it also holds down the motor brush plate so good time to check your motor brushes by pulling it out, mine were still plenty long, you can check the other side while you are at it.

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Original Voltage Regulator now removed (75AMP Air Conditioning XJ6 Series 3).

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New standard voltage regulator by Transpo IL219 (Transpo is the maker and brand name),
(it is listed as 65 amps but I understand it can range up to 80 amps by design):




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Article by Lucas confirming the change to a two-wire voltage regulator where the red wire is now built into the unit and no longer needed.

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New voltage regulator installed via bolt and yellow and black wires hooked up.

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Replacement 5 inch bolt vs the two original bolts. Since 5 inch bolt is same size threads, used two washers and one nut off the original bolts to install the replacement 5 inch bolt. I purchased the 5 inch bolt at a larger sized ACE Hardware store.

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The Alternator is now re-installed, and belt tensioner set. Job Done!
Drove the car around and the voltage stayed at 13.9V to 14.1V steady all the time no matter what accessories were used including headlights turned on.

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excellent work but is there a reason you didn't just pull the alt out of the car? After all you removed those difficult pivot bolts so the alt was free.

 

Remove the 'end-links' from the stabilizer bar and push the bar out of the way. (swing it out of the way)
The alt will FALL on the ground so be sure and catch it.

 

I recently had mine rebuilt. Voltage dropped down to 12.1 while driving home at night. If I do need to do it again, Ill try this approach since everything else is new inside.

 

Yeah, personally, I would much rather repair the alternator on the workbench rather than under the car. But there's more than one way to skin a cat and LCM's posting has a lot of good info !

Cheers
DD

 

Jose,
For me it is now cold in Wisconsin so it cut out the sway bar step and was easy enough to do on the car as I knew it was just the voltage regulator as the issue. If one wants to rebuild the alternator, then moving the sway bar out of the way it the best and easiest way, that is great advise.

The writeup also confirms from the LUCAS article that the voltage regulator was indeed changed to be just a two wire regulator vs the original 3 wire; I have seen many people get very confused by this and search for the very hard to find new old stock three wire ones and then only to pay a very high price for it, so this answers that question and the new two wire units are available for only about $14.00 USD.

I bought the car for my teenage son as his first car as he wanted a vintage Series 3 so I figured why not while he is in highs school is should be a neat experience, as one never forgets their first car! Lets hope its a enjoyable and a rather reliable experience; the car is mechanically up to date.

Cheers.

 

Yes I have replaced the alternator once through the bottom and it was a greasy pain. But with the a./c compressor above it it's even worse.
Who sells this updated regulator? I kept my old Lucas replacing it with a GM and it has been a dissapointment.

 

It is used in a lot of older commercial equipment also, but easiest way to get is from two sellers on Ebay (I am not affiliated with them at all). Just search iL219 voltage regulator and one will see the two sellers.
OEGParts out of Florida
Batesperformance out of Texas

It is listed to be used for the following Jaguar cars:

Make Model Years Engine Remarks

Jaguar Vanden Plas 88-89 L6 3.6L 3590cc Lucas Unit, 80 Amp

Jaguar Vanden Plas 90-92 L6 4.0L 3980cc Lucas Unit, 80 Amp

Jaguar Vanden Plas 82-87 L6 4.2L 4235cc Lucas Unit

Jaguar XJ12 82-89 V12 5.3L 5343cc Lucas Unit

Jaguar XJ12 1981 V12 5.3L 5343cc Lucas Unit, 2nd Prod

Jaguar XJ6 87-89 L6 3.6L 3590cc Lucas Unit, 80 Amp

Jaguar XJ6 90-92 L6 4.0L 3980cc Lucas Unit, 80 Amp

Jaguar XJ6 81-87 L6 4.2L 4235cc Lucas Unit

Jaguar XJS 82-89 V12 5.3L 5343cc Lucas Unit

Jaguar XJS 1981 V12 5.3L 5343cc Lucas Unit, 2nd Prod

There is also an Ebay seller mantacelecticmotors that sells the rebuild kit of three bearings, motor brushes and the same voltage regulator for $45.00 USD if one is inclined to rebuild their original Lucas alternator themselves.
the listing is titled... Lucas Alternator Repair Kit for JC Bamford Mahindra Massey New Holland Case more.

Cheers

 

thanks for the info. Definitely ordering.