The wiring loom is the complete harness connecting every electrical component. The TD requires careful identification because six main loom specifications were produced during its four-year run, two dip switch positions (dashboard or floor-mounted) combined with three indicator configurations (none, relay on bulkhead, or relay under dashboard). The TF uses a single main loom specification matching its consistent dashboard layout. All looms are supplied in braided construction.
TD Main Loom Specifications
Six TD main loom specifications exist, all in braided construction: The original specification covers TDs to chassis 18882, those with the combined horn push and dip switch mounted on the dashboard, without direction indicators. This is a two-piece main loom. A second variant for the same dashboard-dip-switch configuration adds direction indicator wiring with the indicator relay mounted on the bulkhead, also a two-piece loom. A third variant, supplied as a four-piece loom rather than two-piece, covers cars with dashboard dip switch and indicators where the relay is mounted under the dashboard rather than on the bulkhead.
From chassis TD/18883 in August 1952, when the dip switch was relocated to the floor and a separate horn push was fitted, the loom was revised. A two-piece floor-dip-switch main loom is supplied for cars without indicators, and a separate two-piece floor-dip-switch loom for cars with indicators. North American export TDs from chassis TD/22315 in December 1952 received factory-fitted indicators, and any TD retrofitted with indicators since then will require an indicator-equipped loom. Each TD main loom is supplied in a single specification that serves both right- and left-hand drive applications, with the differences in routing accommodated within the harness itself.
TD Panel Loom
A separate single-piece braided panel loom covers the instrument and switch wiring behind the TD dashboard. The panel loom is common across all six TD main loom configurations and serves both right- and left-hand drive cars.
TF Main and Panel Looms
The TF uses a two-piece braided main loom reflecting the completely different dashboard layout, switch arrangement, and wiper motor installation introduced with the TF. A single-piece braided panel loom covers the instrument and switch wiring behind the TF dashboard. Both the main and panel looms serve right- and left-hand drive applications.
Connectors and Junction Hardware
The original Lucas wiring system uses crimped bullet connectors with female socket bodies that group multiple wires together at junction points. Single-way, two-way, three-way, and five-way connector bodies are catalogued individually, along with the bullet connectors themselves. These are the practical means of repairing or extending the loom: a damaged section can be cut out and rejoined using fresh bullet connectors and a junction body of appropriate capacity.
Loom Mounting and Routing
Loom tie-down straps in small and large sizes secure the loom to the body and chassis. P-clips in small and large sizes provide additional mounting points for runs of cable along chassis rails and bulkheads. Loom-to-chassis clips secure the harness in its factory-routed positions. Correct routing, following the original path along the chassis rails and through the bulkhead grommets, is important for both reliability (preventing chafing on edges) and for an authentic restoration finish.
Map Light
The TF was fitted with a small map light using a dedicated bulb holder and bulb, integrated into the wiring loom installation. The bulb holder is also used for instrument illumination and warning lamps elsewhere on the car.
Polarity Considerations
TD and TF wiring looms are colour-coded to the original Lucas standard and function on either positive or negative earth, polarity is determined by battery connection and by polarity-sensitive components (dynamo, control box, ammeter, coil, fuel sender, and any LED bulbs). When restoring a car that has been converted between earths, the loom can usually be retained, but the polarity-sensitive components must be matched to the chosen polarity.
Ordering Considerations
When ordering a TD loom, three pieces of information are required: the chassis number (determining the dashboard-dip vs floor-dip variant from chassis 18883), whether direction indicators are fitted (and if so the relay location), and whether both main and panel looms are needed. For a TF, only the main and panel loom selection is required. The commonest TD ordering error is specifying model without chassis number.