Jumpy rev needle when lights on or using alot of power

[James5]

As per title my rev needle jumps about quiet a bit when I have the headlights on or when running a few things at the same time. Any ideas as to how to solve I am assuming bad earth somewhere cheers James

[Alastair]

As per title my rev needle jumps about quiet a bit when I have the headlights on or when running a few things at the same time. Any ideas as to how to solve I am assuming bad earth somewhere cheers James

Check your grey speedo wire is not running next to your king HT lead. Also check the main dash loom earth in the bottom left of the passenger footwell behind the plastic. Also check the connector on the speedo cable in the engine bay. there are 3 or 4 types but they join by the bulkhead near the battery.