turn on lead not switching amplifier on

I have a Kenwood KDC-X889 playing through a Kenwood KAC-8452 and Kenwood KAC-8152D amplifier.

I always had my head unit connected permanently to 12V, but today connected it with the relay setup shown elsewhere on 12volt.com to switch off the head unit as soon as the door is opened. It works great, but now the 8152D doesn't want to switch on.

I have both turn-on leads connected to the head unit, and for more than a year haven't had any problems with it. However, after the relay-installation, only the 8452 switches on when I turn on the head unit.

Now, I've tried changing the leads between the two amplifiers, to no avail unfortunately. The 8152D switches on for a brief moment, but doesn't produce any sound, and the power LED fades almost immediately until completely off; seems almost as if it goes into protect mode, for no apparent reason.

I haven't touched any wires running to the amplifiers, so I really don't know what the problem might be, except for the head unit not supplying sufficient current to the 8152D. The 8452 works flawlessly.

I'll revert the head unit back the way it was (permanent 12V) and see if it works - I'm going to bed right now!

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F R A N S
1985 Mercedes-Benz 230E
320 000 km / 199 000 miles
Full MB Service History

Ok, did you connect the wire from the relay (retained accessory) to the red wire or the yellow wire. It should be the red wire and the yellow one should be on a good constant 12 volt fused source. Secondly there is a way to boost the power of your remote turn on lead and that is shown in the relay section of this site called adding accessories to remote turn on lead, which will require another relay. If that dont work connect it like it was and ask for help or leave it as it was. another thing usually an amp that goes in protect mode shows a red light and doesnt turn off, well it wont work but it will show a red light. Also if the amp hasnt blown a fuse or the red light isnt turning on and the main power and ground wire test fine the amp is  probably ok and its just a wiring mistake or not getting enough juice on the remote lead, well good luck hope this helped.

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THE DUCE

Well, this afternoon I applied 12V directly to the turn-on terminal, without the head-unit powered on.

The power indicator lights up for a brief moment, and then pulls off a 'domelight' on me, i.e. turns on for about two or three seconds, and then fades until it's completely off. I doubt whether it's related to my relay installation. It seems as though the on-board relay (does the amp have one?) is busted - although I don't really know why.

I disconnected the battery negative-terminal when I worked with the relays, and - like I said before - the other amplifier is working perfectly.

Any other possibilities, or is this a job for an electronics specialist?

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F R A N S
1985 Mercedes-Benz 230E
320 000 km / 199 000 miles
Full MB Service History

Its hard to understand what your saying, if i were you i'd let some one look at it who does know what they're doing.

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THE DUCE

Problem solved !

I took the trusty test light and tested the 12V wire on the faulty amp. No current at all. Did the same with the four-channel, it lit up perfectly. So, I knew I had a power problem.

Went to the engine compartment, to the inline fuses. Applied the test light to the first fuse (oh, I have two inline fuses and power wires, one for each amp). It lit up, tested the second fuse, nothing. Did the same in front of each fuse, now both wires lit up.

Seems the one fuse's contacts somehow disconnected (it wasn't blown). So, all I had to do was buy a new fuse, problem solved!

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F R A N S
1985 Mercedes-Benz 230E
320 000 km / 199 000 miles
Full MB Service History