Disco 2 Highline radio works but no sound

Hi all,
I have a disco 2 with the highline radio with CD changer and Harman Kardon amplifier, I've had the vehicle for about 6 months and whilst the radio and all controls, steering wheel and CD changer all work ok, no sound comes out.

I've read through a lot of forums and viewed all the wiring diagrams and have yet to track down the issue, the testing I've done thus far is:
Power to head unit - Good constant 12v
Power to amp from head unit - Good constant 12v
Remote power to amp from head unit- Good 12v when ignition on
3rd row passenger headphone jack- Good
Using a pair of headphone I was able to jump a wire to two of the amp speaker inputs and the music was coming through.

Short of declaring the amplifier is broken, the only thing I have tested and not to sure on is the SLABs input into the amplifier, the wiring diagram and description shows/says there is an input to the amplifier which turns the volume of the speakers up in proportion to road speed.
With the car not running the voltage at the amplifier is showing less than 1v, I don't know if this is to be expected or not.

If anyone has anything else I can try testing, or some information on the SLABS input, would be greatly appreciated.

Cheers

Sorry, forgot to mention that the radio has worked about three times.
I've just been driving along and out of no where it comes on at full volume and scares me half to death, but haven't had it stay on for more than a few minutes.

Sounds like your amp is toast, most sound problems, if everything else works on your stereo point to a faulty amp

+1
I'd go with the problem being the amplifier. They are available on the second user market.
From what I understand, the input from the SLABS is a trick to try to combat road noise; the faster the vehicle goes the louder the road noise, so the SLABS automatically increases the volume with speed and decreases it again as you slow down. I don't know whether it actually works on mine, if it does the changes are almost imperceptible.

Bad connection or dry joint in head unit i would think. If it's a Clarion they are known for it.

Is it worth while me opening up the radio and have a look?
I opened up the Amplifier and looked for any dry joints, obvious damage and signs of water damage, but didn't notice anything obvious.

beetroot4000 said:

Is it worth while me opening up the radio and have a look?
I opened up the Amplifier and looked for any dry joints, obvious damage and signs of water damage, but didn't notice anything obvious.

Click to expand...

If you do a search for the model of Clarion radio you have you may find repair options for known faults. I sent mine to Clarion, refurbed for £99.00 but obviously that is not an option for you, unless there is a Clarion repair shop where you live.

Can you test the amplifier itself? Rig up a test lead that connects the audio output from, say, a CD player into the amp and see if sound comes out - for more than a few minutes, anyway.

From what I know of the Hi-line ICE system in the Disco 2, there are two power feeds to the amplifier. The first is the one you've checked, show on the attatched diagram as "System enable" which is the on signal to all the amplifiers, Power amp, aerial amplifiers and headphone amps, the second feed is the primary 12 volts which is a higher power feed directly from its own fuse. The system enable circuit is a low power 12 volt output feed switched by the on/off switch on the head unit.

The head unit might be a Clarion, but is more likely to be the Alpine R990 radio if it's still the original fit.


If you have a copy of RAVE, the wiring for the entire hi-line ICE system is in it, for both the Harmon and Lear amplifiers.

I have just been looking at this my self as the radio just died a death on the wifes d2.
There are 2 main inputs to the head unit constant 12v and switched 12volts the head unit then supplies the amp via the red and blue wire 12volts to switch on.
Common faults for your fault as wammers said is dry joints on the main circuit board at the rear where the socket pcb is solderd to the main pcb.
I found our radio had been previously resolderd here.
The other fault relates to a relay under the dash behind the glove box it seems a common problem to but i found no relay under our dash.
I declared our radio dead as 2 metal brackets from the tape deck had come astray and got under the pcb i suspect shorting it out. Shame as i now have a crappy jvc unit that came with the car plugged back in it works but we lose steering wheel controls and rear headphone option.
But we have sound !!!

brian47 said:

From what I know of the Hi-line ICE system in the Disco 2, there are two power feeds to the amplifier. The first is the one you've checked, show on the attatched diagram as "System enable" which is the on signal to all the amplifiers, Power amp, aerial amplifiers and headphone amps, the second feed is the primary 12 volts which is a higher power feed directly from its own fuse. The system enable circuit is a low power 12 volt output feed switched by the on/off switch on the head unit.

The head unit might be a Clarion, but is more likely to be the Alpine R990 radio if it's still the original fit.
View attachment 143546

If you have a copy of RAVE, the wiring for the entire hi-line ICE system is in it, for both the Harmon and Lear amplifiers.

Click to expand...

You are correct, its the Alpine R990.
I have checked and confirmed the RU "system enable" at the head unit and amp and they switch on and off as expected.
I have checked and confirmed the P "permanent battery feed"
I have checked and confirmed the LGP "Auxiliary feed" at the head unit and amp

I've got RAVE and have been looking at the wiring diagrams, will have to have a look for the connector diagrams.
I may try rig up a test rig as some else mentioned, see if the amp works.