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Wondering if I should use my 2007 manual 4WD to jump start other vehicles? We were asked for a jump start by someone with an older car the other day, but my aunt said she'd heard that you shouldn't use modern cars to jump start others because it can stuff up the computers...although she wasn't certain of the details and said maybe it's just if they're automatics? Anyway, we didn't do the jump start and they found someone else, but can you clarify? Thanks.

This has turned out to be such an interesting question to research.

We made contact with a number of our contacts within the industry including our own Roadservice team, our most trusted and well respected auto electricians and those who repair vehicle electronic components (computers).

Most of them caution against jump starting as a general statement. However, they all said they do jump start cars on a regular basis but are very pedantic on using a particular procedure and were also definitely nervous about some particular vehicle brands.

Our Roadservice team gave a special caution about French cars (Peugeot/Citroen/Renault) being used as donor vehicles. From their experience they felt the on-board electronic systems are a little less robust and therefore high risk when it comes to jump starting.

If there are no other options and people want to take the risk, then we recommend the following procedures are used.

• Connect the red lead plus to plus on each battery terminal

• The negative lead should be connected direct to the donor battery terminal however the other end should be clamped firmly and directly to the engine block on the vehicle with the flat battery

• All leads must be attached firmly to avoid sparking

• Start the engine on the car with the charged battery first and then start the vehicle with the flat battery

• One recommendation was to switch on the rear screen heater or head lights on the vehicle with the flat battery as this will help to trigger the alternators regulator to help avoid the risk of an unwanted power surge.

• Both vehicles should be left to run for up to fifteen minutes without revving either engine.

• When removing the jumper leads, leave the engine running and disconnect the negative lead first.

  We need to reinforce the message that for peace of mind sake the best recommendation is to make contact with an experienced service provider (such as the AA) or enlist the help of someone that understands vehicle electrics.

  We also emphasis the high risk of expensive damage to the on-board electronics if the jumper leads are incorrectly connected.

No mention of using jumper leads with protective devices in them (diodes? circuit breakers?). Perhaps this is assumed to be automatic with modern cars. Any comments, please?? Doug.

With my jumper leads they come in two pieces, connect to the batteries then join in the middle the AA must know something about this.

Fair comment Doug.

Part of the interesting investigation into this story was the discussion around the type of jumper leads that should be used.

The general agreement was that if the leads are connected/disconnected properly there is no disadvantage in using leads with no in-built protection.

At the other end of the scale there are no guarantees that leads that do have the in-built protection will actually protect against damage to either vehicle if connected incorrectly.

That's great info, will use it next time I end up in the unfortunate situation of a flat battery :)

It is always a worry jump starting a new car, never know what will fail.