Crown amplifier xls402 fault indicator remain on and protection relay is not switching

It is difficult to troubleshoot this type of problem online. If the fault indicator is not on and the outputs are OK, then I would suspect something in the protection circuit. I would start by checking the supply voltage on the protect relay, relay coil (may be open), and capacitors near the protect relay. If the fault indicator is lit, I would suspect a leaky bias transistor is causing a dc voltage at the output.

Try first unplugging power cable for five minutes , see if it reset.

I would suggest you take it to your local Crown repair depot. It sounds like a fault in the internal protection circuits or the outputs are blown. Without a lot more information I cannot help.

Check speaker to power bank protection circuit. The circuit is faulty indicating to the power amp that speakers are disconnected that shuts down the amp to protect the unit

It is possible that the amplifier had encountered a fault with a higher current drain which had triggered it to a protection fault condition. The fault can be your output drivers- the MOSFETS/IC's fitted for both the channels, Use a meter after disconnecting to check for short in the drivers. Disconnect the positive and negative voltages to the output and see if the protect changes. Even a fault in the preamp stages that drives in high current into the output can shut the Amplifier. Sometimes this can be a noise like a HUM or HISS before the protect works. Faulty capacitors in these circuits also can cause similar issues and needs close observation.
You need to confirm and replace the specific stages or outputs. If not there can be issues in the mother board, maybe the protect circuit by itself is shutting off due to a faulty bias , maybe a leak in any voltage/current sensing circuit. Also disconnect the speakers and test, if the protect is off then check for short on the speakers.

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Try changing the emitter resistors near the parts you've replaced. Also when you change out transistors it's a good idea to change them ALL out..The "supposedly good" ones may be badly stressed.
If the output line to the spkr relay has more than a volt on it the amp will stay in Protect

Nice amp. There is a breaker/switch on the back that trips to protect the amp. Turn it off, then back on and see if the green indicator comes back. If the breaker trips again, that's probably an indication of a more serious internal problem.

if ur output power amp is defective u will have that problem - meaning the moment u connect load across it it will go into circuit protection to limit/stop excessive output current. make sure the speaker terminals are connected to +/- output terminals. in bridge mode use only channel 1 and that too with 4 ohms speaker only otherwise amp will clip. considering all connections are okay if it still clips when speaker is connected, u have a faulty power amp section. this the way ur amp is designed

It is probablly in protect mode due to a failure. This prevents blowing your speakers.

You will need to have or do servicing on it. First verify that you can unplug ALL INPUTS and that speakers are connected and problem of the protect LED exists. A bad input MIGHT be causing this due to a ground loop.

Make sure NONE of your speaker leads are grounded or shorted.

Is it clipping for real or overheating ? It may just be a fault with the indicator light circuitry itself. Make sure the input levels of the amp are matched with the output levels of whatever device is running into the amp, they will either be +4 dbm or -10 dbu, if you have a choice you want them to be set at +4 dbm. Crowns are professional amplifiers and withstand years of hard touring on the road, it would definitely be worth it to take it to a good repair shop if you can't remedy the problem yourself.