From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Guide on how to diagnose and trace an electrical earth fault in a vehicle's system.
| Identifier | ExFiles\Box 26\2\ Scan135 | |
| Date | 19th July 1917 guessed | |
| -21- Contd. TRACING AN EARTH. Some of the symptoms of the occurrence of an earth on the system were indicated in the paragraph on Junction Box P.12. If the earth is on a negative conductor, first find out if such earth only manifests itself by the melting of a fuse when a switch is on, e.g. steering column, psuh button, lamp switch or Klaxon button. In such a case the earth is on the connection beyond the switch in a direction electrically away from the negative pole of the battery. Otherwise the earth must exist on a lead in permanent connection to the negative pole of the battery and may be traced by disconnecting such leads in turn and watching for its disappearance. But it may, with the help of the wieing diagram, be judged in the first instance upon which side of the ammeter the lead containing the earth is electrically situated, by noting whether the ammeter is affected whilst the fuse is being melted. An unintentional earth occurring on any conductor in direct connection with the positive side of the system will cause no immediate dislocation, but is undesirable. If suspected, remove positive fuse when the horn and battery ignition should normally become inoperative. If such is not the case an earth exists and should be traced by disconnecting such leads in turn until the horn and battery ignition are rendered inoperative with the positive fuse Contd. | ||