Battery Terminals Cars affected: Possibly all cars but definitely Evo’s 4-6 Symptom: The engine and all electrical items, may suddenly die briefly and then return, or it may die completely. It will, more likely, occur at low or idle revs or when going over bumpy ground or when turning on a high drain electrical item (A/C or headlights etc). This is not to be confused with the engine revs and headlights dropping/dimming slightly when the A/C comes on as that is normal. Problem and cure: This tends to be one of two problems. One is a faulty, corroded or loose earth or negative lead that can be cured by cleaning and securing it correctly. If you do have corroded terminals then it can be removed using boiling water (with a touch of ammonia) but make sure you wash off any residue from paintwork. It could also be a loose or corroded Positive Battery Terminal clamp. The Positive Battery Terminal clamp is made from soft lead and it is easy for it to be over tightened as there is little resistance when tightening it up. If you over tighten the clamp then it deforms so the ends touch, all the bolt does then is hold the ends of the clamp together rather than actually put any clamping force onto the terminal post. This can cause it to corrode but in most cases the fact that the clamp is loose is the problem. In some cases after tightening the clamp supposedly securely but incorrectly, the whole clamp and lead can be easily lifted off a couple of days later! The cure for this is to unbolt the clamp, prise it back open and re-profile it back into the correct shape (see the diagram). This is just a case of using a suitable former the same size as the battery terminal (say a tapered screwdriver handle) and hammering it back into shape carefully. Refit the clamp making sure you don’t over tighten it. Approximate cost of repair: N/A Back to question page