naimodo

Hello everybody. When I turn the key to "On", the voltage gauge reads 11V. Engine spins fine and cranks. So I know it's getting the proper voltage but the gauge seems screwy. While driving, it varies from 11.5 to 13.5V. There's little rhyme or reason to it lol. It'll be fine one time, then way wrong the next. Before I try to track down another gauge cluster and swap them, I was wondering if anyone else has had a similar problem and if there's was a fix or a way to re-wire it so it reads better/ accurate. We're tested the alternator (series 4 or 5, now sure what year) and the battery, and both check out. The car runs great, but I'd like to fix the gauge if possible. Thanks.

MM54

I've noticed this on my '85 as well, it sometimes sits right below 12 and sometimes is up around 14 where you'd expect, but a multimeter on the battery always hows 14ish when running. Curious if this is a known spot for a grounding issue or what. I'm currently swapping out my volt gauge along with my burned out oil pressure one (they're on the same insert) so I will be curious to see if it still happens or if this is a failure mode of the gauge.

mazdaverx713b

iTrader: (91)

Before doing anything you need to test your source voltage, which is your battery. Use a multimeter and test to see what the voltage is at the battery. You may be experiencing a voltage drop somewhere between the battery and the cluster. There's quite a bit to check honestly. You'll want to check to make sure the battery connections are clean and tight and that all grounds are clean and tight. Check the alternator belt tension to make sure its properly tensioned as a slipping belt can cause a voltage drop when the engine is running. There's a good chance that the cluster is just fine honestly. Remember, you're dealing with 30 year old wiring. Also, you can check your alternator's output with a multimeter and see if the gauge is close to the output voltage from the alternator.

MM54

As a follow-up on my earlier comment - I replaced this in my cluster simply because it's on the same module as the oil pressure gauge, which needed replaced. It may be a function of the new-er gauge from the donor cluster or due to having unplugged and plugged back in all the connectors (which would clean them some) but my volt gauge now reads right on 14 (which agrees with the multimeter) at all times while running (well, the headlights drag it down a hair).