1988 Isuzu NPR: All "warning" lights except those for oil pressure and low charge are on. Any ideas of what the problem may be? Thanks.
Much thanks! Due to weather, I didn't have an opportunity to check the output voltage as you suggest. My first thought, however, is wouldn't a low voltage condition be indicated by the "discharge" indicator light -- which, in this case, isn't on (?) Thanks again.
All warning lights are on EXCEPT those for oil pressure and low battery . ' Sorry if I confused the issue by referring to the "battery" light as "low charge".
Voltage check at the batteries with engine running indicates 11.8 volts which is same as battery voltage (when completely disconnected)
UPDATE: upon reconnection of batteries the "BATT" light is ON -- other warning lights remain on (same as prior to battery disconnection/reconnection)
The alternator was rebuilt recently (less than 100 miles). This truck has been to three different truck service shops (including an Isuzu dealer) -- same story every time -- everything's fine for a few miles, then the same problem reappears. Now, $2000 later, it's going back to the dealer's shop first of the week.