99' QX4 won't start, turn key and 1 strong click!

[elewis6661]

This started around 3 days ago and I am almost at my wits end. I was going to work when I got in my truck, turned the key and I heard I strong click from the engine bay and all the "idiot lights" went black. When I turned the key off and back on again the idiot lights were very dim. Turned key nothing, waited a few minutes and when I turned the key on the lights were bright like they should be only to turn the key and here 1 strong click from the engine bay and the dash lights go black again.
I checked (and replaced) the negative cable because I could not tighten any more and it was not grabbing the battery post. I cleaned the positive cable and all the connectors, I changed a couple blown fuses (15'), and after reading many different posts and my past experiances with working on my cars I made the judgemnt call to replace the starter solenoid only to find a replacement statrter for a few bucks more. The issue is still happening so I am guessing it isn't the starter or the solenoid. The battery is a couple of years old and is holding steady at 12.57 volts. I am leaning towards the ignition switch but I would love to rule out the battery as well.
I don't have any trouble codes as I can't get the motor to even crank over let alone run. I would really appriciate a proceedure or work flow process to follow to diagnose this problem and get it fixed. It appears I have power going through the entire system up to the starter solenoid when bang! It's like my system shorts out
I read on a instruction booklet for installing the starter that if you use your multimeter and test the positive cable at the starter with positive lead of the DMM and ground the negative lead if you read 0.0 - 12.0 volts your cable is bad. but how can it be bad if you are basically checking the positive terminal to negative and mine was reading 12.54volts

[Towncivilian]

Once the engine is running, it runs fine, correct? What's the battery voltage after the engine is started? Is the "SECURITY" LED lit solid after a failed start?

[elewis6661]

I suppose it would but i can't get it to start!
So no start= no run!!!!!!!!!! "QX4 won't start, turn key and 1 strong click!"

[Towncivilian]

Oh, my apologies, I must have misread. Please check if the "SECURITY" LED is solid lit after a failed start.

[elewis6661]

Still flashes after it resets itself.

[Towncivilian]

So it just continues flashing like normal, no rapid flashing?

[elewis6661]

Still flashing normally

All fixed turns out i needed a new battery

[fueler]

strong click=

1. check battery

2. check starter

[BoostMyQX4]

Maybe you need a NEW battery to give the starter the right jump to start the engine.