Mtx tna251 amp I connect +ive and ground..lights start flashing lightly and rapidly..it's not in protection mode

From what I can recall that is usually due to ground, a short if you will.Check your hot cable from under the hood to inside cabin the wire might of got a cut some where rubbing against sheet metal of car creating your short.

THE GREEN LIGHT SHOULD SHOW WHEN AMP IS POWER UP AN RED WHEN IN PROTECTION MODE

CHECK YOU CONNECTION YOU MAY HAVE PUT WIRE TERMINAL WRONG AN THE AMP GOES TO PROTECTION CHECK ALL SPEAKER TOO

Bad connections or a bad amp

How do I get my MTX Terminator TNA251 out of protection please. It's driving me crazy. Is the amp no good.

on some amps there is a duel light. red and green usually. red means it is in protect mode or you didn't hook up your remote wire. if in protect mode, it could mean a number of things. did you hook it up with speakers and everything?

I have the same sub combo. The problem is the amp is underpowered for the 2 MTX 12s, get a bigger amp and you should be fine.

The red light indicates that your amplifier is in protect mode. Amps go into this mode if there is something wrong with the setup of the system to prevent fatal damage to the amplifier circuitry. This is bad thing since the amplifier will not function until the problem is solve and it can remove itself from protection mode.

Amplifiers can go into protect mode for many reasons but one of the most common is incorrect mounting. Is your amp sitting on the metal of your vehicle? Is it bolted down and screwed into the metal of the vehicle or your seat? The amp should never be touching any sort of metal. Only the ground should touching the metal of your vehicle.

Speaking of grounds, many people often neglect proper grounding which can cause an amp to go into protect mode. Do you have a solid ground? Is the wire less than 3 feet long and directly connected to a non-painted metal part of your vehicle? Is the ground wire the same gauge as your power wire?

These are just a few reasons why an amp can go into protect mode. You can find more information here. Or simply google for why your amp is in protect mode.

its just a power light to let you know its on

You will need to show it to a service technician as it seems the output section has blown so it remains in protect mode. One reason (could be) that the input to the amp was high and may have been clipping for some time before the amp decided it could take it no more