Cranks but NO Start... need help

[inthevalley]

I put the battery on a charger for a few days and got some better leads for my multimeter.

With the key off battery voltage is 12.3 or so. With the key on it drops to 12.16. At the power wire to the ignition coil plug it is 12.08.

I measured resistance between the red-green wire by the ignition coil plug and and the red-green wire right outside the ECM (i hope they are the same wire...) and got a huge amount of resistance: 600 at the 2000 ohm setting. Seems like either that wire is damaged or I was testing it wrong. Voltage between battery and that location was still 12.08 volts...

Also, spark plug test light showed no spark at all on the one cylinder I tested

However, when I hooked up my scan tool and tried to rev the engine again I noticed that, although cranking, the tach did not move at all in either the truck dash or my scantool app: 0 RPM.

The result was the same when I tried jumping it. When I started this project I remember getting a couple hundred RPM so this has me confused.

Maybe I have a totally bad battery? 12.3 seems low, my other vehicle was 12.6 with key off.

Once again, I really appreciate all the help!

 

[RonD]

A new battery will read 12.8-12.9volts, 100%
2 years old, 12.6v 75%
4 years old 12.4v, 50%
5/6 years old 12.3v with key ON, time to shop for a battery sale

12.2v or lower with key ON is a failed battery

If you have volt meter on the battery and you can SEE voltage dropping, then it has a shorted cell and is self draining even if unhooked from the vehicle.

Battery's use a chemical reaction to store and discharge AMPs, so the chemicals get used up and the plates inside get build up on them so over time they "wear out", 5 to 6 years is average , but some last a bit longer and other can fail at 4 years if they are drained down too many times