I have read many posts concerning the alternator and battery.
I could not find the reason why my voltage gauge is not
telling me the truth about the real voltage.
I have a 1997 4WD 4 Door Blazer, Vin W.

I just changed the battery this week.
The alternator is only about 5 months old.
The voltage gauge on the dash is the only gauge
that is acting strange. It usually stays steady at around 11 volts.
Every once in a while it will go up to the proper 14, but
it makes it way back to 11 sooner or later.


I cleaned all the grounds I could find and double
checked all connections between the battery and alternator.
I also checked the multiple junction box on the drivers side
for proper connections. Everything looks clean and tight.
At first I thought I had a short, I don't know if I do or not.
I tried pulling fuses while the vehicle was running to see
if there was a circuit causing the voltage drop on the gauge.
Nothing I could find. The voltage stays a steady 11.

I don't have a problem with lights dimming or anything
of that nature. I can have everything on with no noticeable loss of power.
The alternator and battery are both doing
what they are suppose to do. I have taken it to 2 different
mechanics and both have told me the alternator is fine
and that the voltage gauge is just not telling the truth.
I have wiggled connections everywhere to see if I could
get a change. Nothing. If anybody has any helpful tips
it would be greatly appreciated. Thanks.

 

What does the voltage read at the battery?

 

The battery was tested while the vehicle was running
and it read around 14 volts. I took it to Autozone
for the first check. That is where I bought the battery.
I then took it to 2 other mechanics and they both
tested it and their outcome was the same. On
both readings it came out around 14 volts.
They both told me that everything was working properly.

When I told them the gauge was only at 11, they both
told me it was incorrect. Of course they did not tell me why.
There best guess was an electrical issue. possibly a connection.
I just don't know where to look.

 

Sounds like the guage in the instument cluster has gone bad. You could drive around with one of those cigarette lighter plug in volt meters just to verify this.

 

Thanks bandidolenny,

I can try that as a backup to double verify the reading.
Are those things expensive? Have you tried one before?

 

im not 100% sure, but the volt meter is fed to the alternator. i would check all grounds for the gauge and i would check at the backof the cluster. What Does it read when you just have the key in the on position?

 

Your best best is too look at back of instrument cluster, you could check the ohm reading at the gauge, excessive resistance could mean a bad ground or the gauge is bad, if the gauge is bad you can just take those feed wires and buy an aftermarket V Meter Cheap

 

I tried the cigarette lighter meter which I bought for $13, not a bad deal.
It read 14.2 to 14 .7 when the car was running at about 1500 rpms.

The actual volt meter gauge on the car was still at 11 or 12.
I guess this confirms that the volt meter gauge on my truck
is not correct. I can live with this. But how hard is it
to get to the connection that is inside the dash to check that.

Thanks for everybody's help.
Mark

 

I am not sure if the gauge cluster gets a voltage reading through a wire or if it is controlled by the PCM or BCM... I know that a lot of the gauges are controlled by the PCM/BCM through the serial communication bus. You would have to look at the gauge cluster pin out to see what wires go into it.

As far as getting it out of there, that is not all that bad. A few screws to take off the lower cover, then a few more to remove the gauge surround, and finally a few more screws to take off the cluster.

 

Thanks for the info Kyle,

I will try following the wires to see where they go.
Maybe I will try taking the dash apart.
If they all go into the PCM, I don't think there
is very much I can do for a fix.

Thanks again.

Mark