AC Aceca Lucas Wiring Diagrams
There is no electrical section in the workshop manual. The factory Lucas diagrams held by the owners club are effectively the only route, and four diagram numbers are recorded.
The four Lucas diagram numbers
These numbers come from the AC Owners Club forum rather than from a published parts list, which is why the archive treats them as the best available record rather than as factory gospel. They are period specific, so the right one for a car depends on its chassis number and build date.
| Lucas number | Date | Covers | Notes |
|---|---|---|---|
| W29340 | April 1955 | 1955 | The earliest diagram found. Shows a single-speed wiper. |
| W29340A | March 1957 | 1955 to 1957 | Supersedes W29340. |
| W31520 | April 1956 | 1956 | Superseded by W31520A. |
| W31520A | February 1957 | 1956 and 1957 Home and Export models | Supersedes W31520. Described on the club forum as an Ace diagram, while a copy offered for sale was described as an Aceca diagram. Since the Aceca is a bodied Ace, one diagram may cover both, but the archive does not assert that. |
Where to get a copy
The diagrams are obtainable through the AC Owners Club archives and library, and through the members' area under the model directory. The practical advice from members is to ask on the club forum quoting your chassis number, because the diagrams are period specific, and to get an A3 copy rather than A4, since the diagrams do not reproduce legibly at the smaller size.
Autosparks, who manufacture replacement harnesses, supply no fitting instructions or diagrams with the loom. That is not a criticism of the harness; it is simply why the club archive matters.
What the archive could not establish
Whether W31520A is strictly an Ace diagram, an Aceca diagram, or a single drawing that covers both body styles. The club forum and a commercial copy give different descriptions. Since the Aceca is a bodied Ace, either could be true, but the archive has not seen evidence that settles it.
The archive also could not confirm whether any of these diagrams were revised after February 1957, or whether additional numbers exist for export-only equipment or for cars fitted with an alternator later in life.
Related reading
- The wiring loomWho makes replacement harnesses, the Lucas colour code and the earthing problem.
- Positive earthWhat the polarity means for battery, coil, dynamo and accessories.
- The Lucas control boxWhat the RB106 does and its commonest fault.
- Horn and indicator wiringThe stator tube, the Lucas switch and how to thread it.
- Clubs, registers and recordsWhere the factory records live and how to reach the club archives.
- Parts and specialistsWho supplies parts and who works on these cars.
If a diagram number is wrong or missing, or if you know of a better source, please get in touch.
About the author
A lifelong classic-car enthusiast in North Yorkshire, near Thornton-le-Dale, who owns and maintains an AC Aceca, writing the single-model reference he always wished existed. Read the full bio.