Quick replies/1/3

Q: I drive a 1994 model VW Jetta 3 CLX and I'm experiencing a problem with the instrument cluster. The odometer, trip meter, speedometer and fuel gauge are doing crazy things, going blank, jumping around, giving false readings. I have twice replaced the cluster with ones bought from a scrapyard but the problem still persists. - Phillip

A: Phillip, I don't think the problem lies in the cluster. In fact the clusters on those Jettas are not known to give trouble. It's more likely that there's a problem in the speedo drive unit on the gearbox.

I suggest you locate the speedo drive and have a good look at the condition of the unit and its wiring attachment.

Perhaps you only need to clean up the contacts where the plug fits. If the unit is damaged beyond repair, a new one should not cost you the earth.

FOR umpteen years, I have checked the water level in my car battery as well as the specific gravity, every month. By doing this, I have felt reasonably assured that I would pick up any warnings of a declining performance and impending demise.

Q: However, with a new "high tech" battery, I am told that the best I can do is to just keep turning the key in good faith and when, eventually, all I get is an exhausted groan, then I'll know that I need a new battery. - Stu

A: There are several ways of testing a sealed battery, but most of them require expensive equipment.

The method I suggest might not produce such a definite and instant verdict, but it only requires a multimeter.

Start by performing an open circuit test after the battery has been allowed to "rest" overnight. A reading over 12.65 volts indicates the battery is fully charged.

However, this doesn't tell you whether the battery can produce the heavy current needed to operate the starter motor while powering up the other electrical systems.

For that you need a load test with as many of the major current-consuming accessories as possible switched on, without starting the engine.

The voltage reading will fall but if the battery is healthy, it should stabilise above 11 volt, and may then rebound slowly.

A battery at death's door will drop below nine volt.