Gaining Access to the Dashboard WiringFigure 2
Before dealing with any wiring always isolate the battery. Even the small battery in a 1970's Morgan can deliver 360 amps at startup A dead short in the unfused starter circuit can burn out parts of the wiring and potentially start a fire.
It is possible to access to the wiring on the rear of the dashboard by laying on your back in the footwell. Whilst this is OK when replacing the odd bulb or switch wire, it is uncomfortable and unsuitable for rewiring the dashboard during a rebuild. Fortunately removing it in a traditional Morgan is straightforward. It is simply secured to the ash frame by two screws as illustrated in Figure 2. Before removing the screws, it is essential to release the drive cable from speedometer. The odometer cable can remain in position. The pipe must also be removed from the rear of the oil pressure gauge and plug should be inserted in the end of the pipe to prevent spillage of oil. The plug will also prevent contamination from an external source.
Removing the steering wheel will also assist in making the job easier when dealing with the dashboard wiring. Also, disconnect the ignition switch 8 way connector and indicator plug
from the steering column. See Figure 6.
Undo the bolt, which fixes the instrument voltage regulator to the bulkhead and unplug the hazard warning and indicator flashers. Remove the two screws securing the dashboard and gently lower it face down upon the transmission tunnel.
The Loom behind the Dashboard
Whilst the wiring illustrated in Figure 1 looks simple enough, removing the loom usually results in the confusing mass of wire as shown in Figure 3. If the loom is original, Figure 1 should be a good guide to the correct wiring layout behind the dashboard. However, studying the circuit diagram in the Morgan handbook is the best practice when renovating and replacing the loom. Always replace faulty wires with the correct colour coded and current rated type. Holden Vintage and Classic keep a good stock.Figure 3
When the main loom has been unplugged from the rear loom and disconnected from the various components under the bonnet, footwell and wings, it can be withdrawn. Laying the loom out will show it to be less confusing than it initially appears. Figure 4 shows my own loom after restoration and how simple the wiring really is. The old loom tape was removed and all of the wires were cleaned and inspected for deterioration and damage. Most of the wires were in good condition but many of the terminals were renewed. Oxidised terminals and connectors increase resistance, so they are best replaced. New non sticky loom tape was used to re-wrap the loom, whilst heat shrink was applied at the junctions and ends of the loom to stop the tape from unwrapping.
The Ignition Switch and Steering wheel 8 Way Connector
The wiring to the 8 way connector on the steering column controls the indicators, horn and headlamps. The colour of the wires and their position in the connector is illustrated in Figure 5. The corresponding plug on the loom is obvious by matching the wires. The ignition switch wires do require matching to individual wires and greater care is necessary when disconnecting them from the loom. It is wise to label the wires when removing the loom. Take particular care when dealing with the brown wires in the loom as they are not fused, except for the hazard warning flasher which has an in line fuse.Figure 5
Protecting the Loom forward of the Bulkhead
In the engine bay much of the original loom was not wrapped in tape. Throughout the engine bay I wrapped the loom in tape and further protected it with expandable braided sleeving, which resists heat and abrasion. The right hand photograph in Figure 6 shows the original unprotected wiring loom clipped to the front off side inner wing. In the two left hand photographs, the grey braided sleeving can be clearly seen protecting the loom. This type of sleeving is prone to fray at the ends,but this can be avoided by sealing the ends with a soldering iron. This is best done before sliding the sleeve over the cables. The best way to prevent the braided sleeving from fraying or riding up the cable, is to seal the ends and junctions with heat shrink. Rubber grommets should be used wherever the loom passes through the car panels, where vibration can cause cables to suffer abrasion. Failure to use rubber grommets may lead to a fire if wires short out on the metal panels, particularly where heavy unfused currents are involved, e.g., the alternator B+ wire. The left hand photograph in Figure 6 shows the alternator cable clipped to the nearside inner wing, ensuring it does not touch and short out on the manifold. The loom securing clips must also be insulated with rubber sleeving.Figure 6