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Old 26th January 2019, 21:41   #1
JB Tourer
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Default High Line Head Unit Blank Screen and Nothing Working

As the title says, nothing is working on the system. All is dry, no water ingress in boot. Sat nav CD drive boots up and shutting down correctly. Have swapped the head unit and both the boxes in the boot for ones from my other car (where they work fine) and still a blank screen and nothing. The screen is blank but is back lit. The head Unit right hand button is doing nothing and the little orange power light is not illuminating.
I checked the voltage on the K bus wire behind the head unit and in the boot. This is way under 1v (should be 12v is I have read other posts correctly) so it is not getting the signal. I guess a bad connection.
Everything else in the car is working including sunroof, reversing sensors etc.
Where does the sat nav loom plug into the standard car loom to start getting the k bus signals? Does anyone know please? If can find this this location I can then trace the cables back and find where the problem is (I hope).
Thx and all the best, JB
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Old 27th January 2019, 19:46   #2
neilll
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Hi Jarrad,
Yes you have a problem on the K-bus (voltage varies between 9-12 if I remember correctly.
I had a problem a year or two back and nearly ditched it for one of Radioguys units (but changed my mind after reading all the horror stories). Any way after seeking advise on hear Bigruss came up trumps with my fault without even seeing the car! The fault on the bus line was traced to the cables just in front of the drivers seat (under the carpet) there is a joint with several cables there and the insulation had become chaffed added with a little bit of water and hey presto! Just saying that this was my fault and if you have checked all visible connections etc. this might be one to try.
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Old 27th January 2019, 21:00   #3
JB Tourer
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Default Sat Nav

Thank you very much. I will have a look there during this coming week and let you know what I find. I guess then the connector this part of the loom plugs in to must be in the centre console area somewhere. Does accessing this cable require the seat to be removed so it is possible to lift the carpet? Thx again and all the best. JB
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Old 26th April 2019, 20:52   #4
JB Tourer
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Default Blank SAT NAV screen sorted

After taking CANBUS readings at various places in the boot it was obvious there was no signal getting to the units in the boot. So I stripped out the interior and looked for the CANBUS joint near the drivers seat. I had already measured full voltage behind the head unit. There is a blue piece of insulating tape in the harness in front of the drivers seat. The CANBUS wires are all joined together for the sat nav here. There are 4 wires coming from the front of the car and three going to the back of the car. These are all crimped together in one join and then wrapped in the blue tape. On mine, the metal crimp had obviously got wet when the sunroof drains leaked. Even though now dry, the damp and voltage had made the metal crimp crumple. Hence the signal was not going through to the back of the car. A quick solder and some heat shrink and its all up and running again. All the best, JB
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Old 20th November 2020, 05:49   #5
Matt G
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Hi There

I think I may have exactly the same fault caused by water damage also.

Jut wondered where exactly did you find the joint with all the wires coming together underneath blue tape.

Was it literally under the drivers front seat running along the cross member, or was it running along the side of the drivers seat heading towards the back seat.

Hope you can help, just trying to locate precisely to avoid pending up the entire sat nav loom in that area to find the joint and test.
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Old 20th November 2020, 22:51   #6
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hi to all
is your rover 75 tourer a mk1 or facelift and have you checked the fuses in the passenger fuse box the header c0289 is on the drivers side
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