Van won't start and no lights come on; battery good

Question

I have a 1992 GMC Vandura 2500 5.7L.

A few weeks ago, I tried to start it. All lights and radio came on but it wouldn't start. I tried again a week after that to show my dad but it still wouldn't start. This time the lights didn't come on either.

The battery is fine, reads 12.8 V. We have replaced the starter, ignition switch, ignition lock switch, and a burnt 15 A fuse, but it still won't start. Does anyone have suggestions?

Answer 1

The battery is fine, reads 12.8 V.

When you measure the voltage while the vehicle is off (no load on the battery), the voltage doesn't say much. The battery can be nearly empty and still show 12 V with no load.

Try measuring the voltage while the lights are switched on.

A few weeks ago, I tried to start it. All lights and radio came on but it wouldn't start

That typically happens when the battery is almost empty: it holds enough charge to power minor users like the lights and radio, but it's no longer capable of supplying enough power to run the starter. The starter draws a huge amount of power, so this is always the first function to fail when a battery is discharged or at the end of its life.

Answer 2

Suggestions:

1. Is the starter motor plugged in?
2. Are you confident that the new starter motor is not defective?
3. Have you re-checked the fuses?

Flat battery one week later:

As for the lights not coming on a week later, you have probably flattened the battery with your more recent attempts to start the car because the car hasn't been driven, so the alternator has not had a chance to recharge the battery. Recharge the battery and/or connect it to an external source of power such as a battery-recharger before future attempts.