Greetings!

I am getting a voltage drop on my battery guage while driving. The car is warm and runs smooth. The drop can dip as low as 9-10 and then will eventually jump back to just under 13. (don't know how accurate the dash guage is. What should it display when ALT is charging?) Also the check engine light goes off and on intermittently but does not coincide with the voltage drop. I don't have a code reader so bear with me. I can hear a bearing going bad in the ALT when I put my stethoscope on it, so I am probably in for a new ALT anyway but I wanted to hear from you guys if this is something more. Thanks for any input.

 

Get the codes ... You don't need a code reader ... Just connect the A and B terminals at the diagnostic port with a paperclip...and turn the key to run....do not start the car...Read the flashes... Should go 1...2...... Three times.... Then flash any present or stored codes ..

research this on this forum before you do it....then look up the codes... Or ask us... I have the factory manuals.

But yes, it's probably the alternator.... The code may confirm it.

 

My dash gauge is pretty unreliable, reads low usually. I got a plug in LED volt gauge for the cig.lighter that reads really close to actual voltage at the battery. I'd start with that.

 

13.3 charging voltage minimum. 14.2 max voltage fully charged battery.

 

First check the battery voltage with the car off. Clean battery terminals until they shine. Reconnect and check voltage at battery with the engine running. Don't have a DVOM?, buy one at HF it's part of owning an antique car.