Pioneer DEH-80PRS voltage display reading incorrect

[95maxrider]

Hi everyone,

I just replaced my older Pioneer HU with the Pioneer DEH-80PRS and the voltage it's displaying on its face is about 0.8 volts low compared to my digital distribution block coming off the battery positive as well as my battery tester hooked up directly to the battery.   It reads about 0.8 volt low with both just the key on and with the engine running.  I know it's not going to be super accurate or necessarily have fast response time, but 0.8 volts is kind of a lot, and it's consistent, so I can't help but wonder if some wiring along the way could be done incorrectly.  I've searched the web for more people using this HU, but it doesn't seem to be very popular, and most people don't have other sources to compare readings to.  Does anyone know if this is just normal operation, and it's just plain wrong all the time, or if something might be amiss? What would be some good ways to troubleshoot this?

Thank you!

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[keep_hope_alive Premium Member]

Have you taken a measurement with your DMM at the head unit power and ground location?  The head unit isn't measuring the voltage at the battery but the voltage at the dash wiring.  The best you can do is match the voltage at the dash wiring where the radio connects.  There can be substantial resistance between the battery and head unit.  First thing to try is a better ground for the HU, i.e. to bare metal on the chassis.

You can scour the manual for instructions on manually adjusting the voltage reading calibration, if that exists.

 

[Popwarhomie 5,000+ posts]

One of mine was a full volt off. Other one is right on. Didn’t bother me though since I ran volt meters.