Dash volt gauge..

[painterdave72]

Im sure this has come up many times before.. but here goes. the volt gauge on my car is reading very low with accesories on such as the ac and stereo with amp and sub etc.. it even reads low when nothing is on and just idleing.. but it charges fine. i have tested with a multimeter and its between 12.8 and 13.2 at idle. when u give it gas it goes up to about 13.8 sometimes little higher.. this is a gm cs 130 alternator i have rebuilt last year with a 140 amp kit.. all my wire harnesss in the front and rear of the car are nos as well as new fuse box etc.. all gauges are replaced with nos one and the circuit board in the cluster is new ... all grounds are clean etc.. its just the gauge reads like 10 volts sometimes.. it has been suggested i pull the alternator and take it to have it tested at a shop... and other suggestions would be welcome.. i will probalby pull the cluster at some point and see maybe there is a loose connection there???

[Bitsyncmaster]

I posted a thread on one way to help with the low volt readings.

http://dmctalk.org/showthread.php?18262-Different-wiring-for-the-inertia-switch

I also posted an old thread about just moving the inertia switch ground wire which also did the same improvement for the volt gauge.

[DeLoreanTech]

I had the same problem. I scoured this forum and implemented many of the grounding improvements suggested and installed many of Dave McKeen's solid-state electronics. I also fortified my cooling fan ground by running a 0-gauge ground cable from the grounding location on the front frame extension all the way back to the driver's side trailing arm bushing bracket bolt, then to the transmission "Hervey" style (also did the Hervey battery ground cable mod with 0-gauge cable). It is also important to use 100% copper cable, not copper-clad aluminum.

All of these improvements cumulatively have helped my voltage gauge read steady at ~13V, even when the A/C system is blasting. I also installed a separate, digital gauge in the car that reads accessory 12V from the center console, as a check against the dash gauge. They both read exactly the same. Once in awhile my gauge will drop and it appears to coincide with heavy cooling fan use over extended periods of time. Next thing on my list is more efficient cooling fans.

[painterdave72]

after tearing my cluster and center console out this past week checking grounds and voltages etc.. I fixed the gauge reading wrong by pulling the needle off it and moving it up a little . .now the gauge reads a little above 13where it should be .. all voltages at the wiring and the gauge are correct and now the gauge reads correctly also. .so just a thought that the needle might have been put on in the wrong position on a lot of the gauges that read .low... the gauge still functions normally and still drops a little voltage when all accessories are on and at idle etc.. but goes to right at 13 when driving with all stuff on... so fixed!!!