Lazy voltmeter

[JohnZ]

Hi there! My car has always been odd regarding the voltmeter reading. But lately it became worse, sometimes the needle doesn't even wake up. Sometimes it measures just 8 volts, sometimes it just bounce to above 13 (correct reading)...

Fuses and fusebox are new, binnacle was out last week end for a bulb test and I renewed the contacts... What the hell?

PS: of course the battery has solid rock 12.6 V if tested with a multimeter, so it's really just a matter of instrument cluster oddity!

:) :)

[mluder]

Could be a bad connection behind the instrument cluster. The tabs where the wiring plugs insert our fragile.
Also, check the ground behind the bulkhead above the parcel shelf, passenger side. Take it apart, clean it, and put it back together real tight. I had all sorts of oddities in my instruments. This cleared everything up.

Cheers
Steven


Hi there! My car has always been odd regarding the voltmeter reading. But lately it became worse, sometimes the needle doesn't even wake up. Sometimes it measures just 8 volts, sometimes it just bounce to above 13 (correct reading)...

Fuses and fusebox are new, binnacle was out last week end for a bulb test and I renewed the contacts... What the hell?

PS: of course the battery has solid rock 12.6 V if tested with a multimeter, so it's really just a matter of instrument cluster oddity!

:) :)

[JohnZ]

Do you mean the ground behind the rear shelf wall? or is it somewhere else?

:)

The plug in the binnacle has been refreshened and secured lately, it it a piece of crap :thumbdown: but now at least I think it has a solid connection!

[Elvis]

What does it read when you test it on the bench ?

do you have a schematic and can you read it ?

8V is extremely low for the parcel shelf Ground problem, the other bulbs,
instruments and devices would do strange stuff, too.

do they ?

[JohnZ]

What does it read when you test it on the bench ?

I had not the chance to measure the voltage through the voltmeter circuit, but the battery is always at full power so the issue lies in the meter for sure.



do you have a schematic and can you read it ?

I do, and I always use the wiring schematic to track down electrical issues.





8V is extremely low for the parcel shelf Ground problem, the other bulbs,
instruments and devices would do strange stuff, too.

do they ?

The other gauges and lights are fine, except for the brake bulb that does not work. But that must be faulty somewhere else in the hand brake wiring! Just the voltmeter stopped working, and sometimes it works fine, and sometimes it reads low (more like 10 than 8, I correct myself).

:D

[Exolis]

Check the harness and contacts first by doing Voltage Drop and Ground Float. Basically you'll measure the voltage from Battery + Terminal to Power feed on Voltage meter. Then do the same for the Meter Ground pin to the Battery Ground. Both should ideally be under 1V. Since it's the Volt meter in the vehicle, it should ideally be low as possible. I would think even 200mV would probably be unfavorable for that application.

If that is the case, then there's probably a dirty/corroded connector/pin that needs to be cleaned.

[Jonathan]

John...

It could also be the connections directly on the back of the cluster. This is a picture of the back of mine when I had it out. The battery volt gauge is bottom left on this image. See how it secures to the backing with the four nuts and bolts? You can follow where the circuitry (if you can call it that) goes. It might be something is not quite right along that pathway or right at the gauge. It's thin and flimsy and gets bent easily. Or it could be the nuts themselves aren't positioned well. I recall there being little washers on most of the nuts that matter (some are not electrical connections, but physical rather to hold it in place). Make sure those washers are in place and connections are good. This can affect gauges as much as bulbs not working.

34075

[Autoboys]

I've had this issue as well and after changing the alternator twice and cleaning all grounds had the same issue.

Try this before disassembling everything.

Behind the passenger seat pull the #5 fuse and clean the fuse blades and terminals for this fuse (most likely will look discoloured)Reinstall and check the gauge.

Let us know.

Steph
Vin02450

[JohnZ]

Ok thanks everybody I'll perform all the tests that have been reported here!

As being said the fuse block and all the fuses and relays are brand new, the connections have been soldered and crimped so fuse n. 5 isn't the culprit in this case!

still I can't really figure out which and where is the voltmeter ground to check!! Any pics?

:)

[Bitsyncmaster]

What can cause inaccurate volt meter reading is the dash ground circuit is common with the fuel pump ground (via the inertia switch). Putting the fuel pump ground onto it's own circuit (I used frame ground) made the dash volt gauge read correct.

If that dash ground went bad, I would think other dash issues would show. My guess is you have some bad connections close to the voltmeter circuit in the dash.

[JohnZ]

What can cause inaccurate volt meter reading is the dash ground circuit is common with the fuel pump ground (via the inertia switch). Putting the fuel pump ground onto it's own circuit (I used frame ground) made the dash volt gauge read correct.

If that dash ground went bad, I would think other dash issues would show. My guess is you have some bad connections close to the voltmeter circuit in the dash.

I currently have John Hervey's fuel pump saver kit installed, and I grounded the pump directly to the radiator bracket, left side of the frame!

So this really points to the actual needle connection, does it?

[Bitsyncmaster]

I currently have John Hervey's fuel pump saver kit installed, and I grounded the pump directly to the radiator bracket, left side of the frame!

So this really points to the actual needle connection, does it?

I would think your meter connections need clean up. Some of our gauges also have a shunt over the meter that would also need clean connections. I would pull the binnacle and remove the mounting nuts on all the meters and clean things up.

[JohnZ]

After replacing the alternator, the gauge was feeling very fine and was constantly over 13 V!

But lately it started to bounce once again up and down with no reason :( I think I'm gonna pull out the binnacle... AGAIN:frantic: