High Line System Dead - Help!

[Dr Funk]

I was in my car about to drive off with the radio on when the system seemed to switch off. I could not switch it back on again. The backlight on the screen was on and there were signs of life from the autochanger, satnav and amps (quiet background speaker hiss). That was a couple of months ago and I have not had much luck since.

The units were dry, though the car had been damp due to the sunroof drain issue but this had soaked the carpets but not the spare wheel area. The battery had run flat and had just been charged in situ when this first happend.

I took the car to Huets (car audio specialists) who could not find the fault so they sent the units off to their repair company. The result was that the TV tuner was blamed but not repairable. I took the tuner home and had a poke around with a soldering iron although everything looked fine I wanted to eliminate dry joints on connectors etc.

They refitted the system and it all worked! Well for a few days until my battery went flat again (yes I'm going to change it!!). After charging the battery the system came on but after a few seconds the screen went blank with a white stripe at the bottom for a few seconds before going off completely. The radio was still working but the controls had frozen, and switching the ignition off and on again left me with a dead system again, just sat nav autochanger and amps showing signs of life and screen backlight.

I took out the TV tuner and did the soldering iron thing, no effect this time, also did the same as much as was possible with the head unit and Radio tuner also to no effect.

Next I bought a Hybrid TV tuner, as expected this did not work, but I don't think it is the TV tuner at fault.

I had found some discusion regarding the k-bus signal but having checked the wiring there seems to be no damaged connections as far as can be seen I have used contact cleaner / lubricant on all connectors. The only thing I could find was where the loom has been hacked into near the head unit but this was I assume for a nokia bluetooth unit and on inspection the connections are neat soldered and covered in self amalgamating tape.

At this point I suspect either the loom or the head unit, I would like to get a widescreen but best to find the problem before spending any more money.

Now I could really do with some help as I would like to verify if my hybrid tuner works and also the best way forward to get to the bottom of the issue. There is a BMW system on ebay which would give me a chance to swap out all the units at a price but ideally if there is someone in the Sussex area with a working highline system that would be prepared to have a swapping session I would be very grateful!

[iandb1970]

Reebs recommended this the procedure below and it worked for me:

Try this reset procedure for the high line ICE, it has worked on other units with the same problem that have been reported on here in the past. The procedure below came from the ICE/Electrical department of MG Rover Product Development.

ROVER 75 HIGH LINE ICE RADIO RESET PROCEDURE.

If the radio in this vehicle sticks on one station and you are unable to select anything other than tape or CD please carry out the following procedure to reset the unit.

1. Switch off unit using main on/off button (one with the orange triangle on the bottom right of the unit)

2. Switch on the unit using the same button

3. Within 8 seconds press and hold the TP button, on the unit, until the radio station read out re-appears and music etc can be heard

4. Switch off the unit again

5. Switch the unit back on and you can then select all radio bands along with CD, tape and tuner.

This should reset your Highline Radio.

[Geoff130]

Hi, I've just retrofitted a Hi-line system over the last month and having made my own wiring harness learnt some things the hard way. The sat nav and cd changer can be removed and the system will still work without them, see else where on this forum how to shut down the sat nav correctly. You can even disconnect the steering wheel interface and still use the monitor controls. At this point you should have the bord monitor, tv tuner and radio tuner. I found my system had to be turned off and back on with the ignition key before it came to life. The k-bus controls all these units and the tv tuner has a permanent battery feed to it and never turns off unless it gets a message to do so over the k-bus, turning on is also achieved the same way. All information about radio status and cd changer is sent over the k-bus and generated as a display in the tv tuner, it is then sent as three video signals to the bord monitor from the blue plug on the tv tuner. Removing this plug should give a plain white screen on your bord monitor, showing the cable to be ok. The k-bus line should be at battery voltage mostly with narrow negative pulses appearing during communication, if you have access to a scope you can check it while pressing buttons on the bord monitor, if you only have a DVM it should appear to be about 12v or higher. If it is low then you have a wiring fault on the k-bus. The k-bus is the white, red and yellow cable. I hope this helps, but to be honest I wish I could have swapped my units into a working system when I was doing mine.

[Dr Funk]

Thanks for the replies,

The first suggestion of resetting the system is not an option unfortunately in my case as it will not switch on.

Geoff, hats off to you! Making your own wiring harness (and then installing it) sounds like a seriously vast job! I'll check the k-bus more closely, I have an old scope which may or may not decide to trigger, but at least I know what to look for. Also I can check for the white screen with the blue plug out, I guess a black screen would implicate the monitor as faulty.

[Dr Funk]

Hi Geoff,

Could I pick your brains again, I have had a go at the following:

Removing the blue plug resulted in a black screen with no backlight
Looking at the Kbus on the radio module connector as this is where it's easily accessible shows it to be pulled low with power and ignition present. It's not a short but being pulled low by some electronics (0.38 - 0.4V)

This was the case with all units except the radio module connected and did not change when the other units (monitor tv tuner and satnav) were disconnected one by one.

Having built your own loom I guess you will have a good idea how the K-Bus is connected. I would have thought it connects all units such that with no units connected it would be floating and that each unit would have its own pull up resistor to 12V and an active pull down by the comms circuit in each unit capable of talking on it.

As I am seeing 0.38V on the K bus something is actively holding it down. With everything except the cd changer connected the only things to my mind that could be causing the problem are the cd changer assuming it's on the K-Bus, or the vehicle must have something connected to the K-bus, perhaps the comms for the steering wheel controls or trip computer which passes info to the monitor via the tv tuner presumably.

Does this line of thinking make sense? I can try disconnecting the CD changer next, and assuming there still is a pull down on the k-bus it must be the vehicle elecronics doing it. If this is the case do you (or anyone else??) have any further ideas?

Thanks in advance!

[Geoff130]

You would think this was the case but there are only two pull up resistors on the whole bus, one in the Instrument pack and another in the Body Control Unit, you can simulate it with a 10k from the k-bus line to battery +ve but one above sends the messages that key is in aux, ign or off. It looks as if your Hi Line bus isn't connected to the rest of the car. There should be a header inside the centre console where the k-bus, Aux power, illumination, and permanent power are distributed. It is about 50mm long, 10mm wide and 20mm deep, usually wrapped in foam tape. You can do a continuity check from here to your units and you will also find the k-bus on the instrument pack and the main light switch. I found on the bench without a pull up on the k-bus the on/off switch of the monitor did nothing, with a pull up, it would illuminate the triangular led next to it and I could now view button press messages. It was only when I put it in the car with the IPK and body control unit connected it turned on properly. What may be more useful to you is that with only power to the monitor and nothing else the screen was blank white as soon as the aux power was turned on. It would go dark ( but still blank) as soon as it was connected to the TV tuner or Nav ECU. I hope this helps, Geoff

[Ross R75]

Originally Posted by iandb1970

Reebs recommended this the procedure below and it worked for me:

Try this reset procedure for the high line ICE, it has worked on other units with the same problem that have been reported on here in the past. The procedure below came from the ICE/Electrical department of MG Rover Product Development.

ROVER 75 HIGH LINE ICE RADIO RESET PROCEDURE.

If the radio in this vehicle sticks on one station and you are unable to select anything other than tape or CD please carry out the following procedure to reset the unit.

1. Switch off unit using main on/off button (one with the orange triangle on the bottom right of the unit)

2. Switch on the unit using the same button

3. Within 8 seconds press and hold the TP button, on the unit, until the radio station read out re-appears and music etc can be heard

4. Switch off the unit again

5. Switch the unit back on and you can then select all radio bands along with CD, tape and tuner.

This should reset your Highline Radio.

Thanks Reebs and Ian, worked for me this morning.