Haynes’ World is where we share stories of what we've been doing with our vehicles.

This time: Nigel’s multimeter gets a workout!

My last report on the Spitfire mentioned its modified ignition system, so with the wiring diagram from the digital version of the Haynes Manual printed out, I lifted the bonnet to search for anomalies.

The manual showed an early Mk4 Spitfire such as mine should have a ballast resistor ignition set-up and I could see there wasn’t one present.

All the connections to the ignition switch were correct and the switch was doing its job. I did, however, find a nasty little homemade cable between the solenoid and the coil (shown below). Removing this meant the car would not start. Having it in place meant the car would not turn off. It needed investigating. 

None of it matched what was shown by the wiring diagram: a green cable was connected to the positive side of the coil and a white cable was running from the other side to the distributor. Then there was that temporary cable from the solenoid to the positive side.

Given that the swap from ballast resistor to non-ballast ignition means a change of coil, had the right one been fitted? Looking at the label, I could see it was a 12v coil, which is correct for a non-ballast system. Using the multimeter confirmed this. It measured a resistance of around 3 ohm. A resistance rating of around 1.5 ohm would indicate a ballast-resistor coil was in use.

The next task was to wire up the coil correctly…

You’ve seen our repairs, now show us yours!

Here at Haynes, we love working on our own vehicles. Diagnosing a fault, then sourcing the bits and carrying out the fix ourselves provides a great sense of satisfaction. Not only that, but it saves us a heap of money – something not to be sniffed at in today's financial climate.

But we also love to see how our customers keep their cars on the road – and this is your chance to show us!

You don’t need to have a shiny workshop, nor do you need to have the production values of Martin Scorsese; we just want to see how you got on, and how you dealt with any ‘issues’. And if you used your Haynes manual in the course of your repair or maintenance, all the better.

Simply reply to this email with the following details:

• Your name
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