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-   -   High Line Head Unit Blank Screen and Nothing Working (https://www.the75andztclub.co.uk/forum/showthread.php?t=292278)

JB Tourer 26th January 2019 22:41

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

neilll 27th January 2019 20:46

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.
Happy Hunting
Neil

JB Tourer 27th January 2019 22:00

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

JB Tourer 26th April 2019 21:52

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

Matt G 20th November 2020 06:49

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.

david2000 20th November 2020 23:51

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
david

Matt G 21st November 2020 11:37

Hi David

Thanks for the reply. Yes I have checked the fuses, I pulled them all out 1 by 1 to check nd that resulted in the sat nav half working.

Basically ignition on , but engine off radio works, tape works but no screen. As soon as I start the engine the screen starts to work intermittently, kind of flashes on and off all the time.

So I figured it could be this wiring connection JB tourer referred too underneath the seat , as I bought my car absolutely full of water, so similar problem.

I have sorted all the other Electrical gremlins out, my central locking and indicators, hazards, heater all work so was tending to steer away from a k bus issue. Do you think it still could be?

C0289 is part of the k bus, can that connector be unplugged and re connected incase the contacts are Corrected slightly.

I was basically figuring it is a bad Power connection Or earthing issue , but I very much open to any other suggestions or pointers.

Seats are out, carpet up, so I have access to most of it

Regards

Matt

david2000 21st November 2020 13:38

hi matt
i am i correct you say that the car was flooded if so then i would say that there is corrosion in the connectors some where you will have to check and if you have a multi meter check if there is 12v going from the fuse box to the head unit do you have RAVE2 consult the wiring diagrams and trace from the passenger fuse box to the head unit i have had an idea take the passenger fuse box off and put it some where warm to dry then check it for corrosion and give it a clean it looks like the fault could be the passenger fuse box a bad connection
david

Matt G 21st November 2020 18:52

Hi David.

Thanks for the reply. Oh yes flooded is an understatement , all sunroof drains, rear lights, rear quarter panel trims and where the towbar wiring cane in, all sorted though now.

Iím actually surprised I have got off lightly with the electrics so far. I agree I think I have a corroded joint somewhere and when the engine is on the alternator is giving just enough ampage to get the sat nav screen to kick in slightly, thatís why I was thinking the joint under the drivers seat as that would of definately been under water, if not k bus connector c0289

Iím going to attack with the voltmeter on Tuesday and figured I would try the joint under the seat first, I just didnít want to start opening the loom in random places to find it unnecessarily to until inlocate it. Hoped some one could point me in the right location.

No I do not have Rave2 to help with the wiring diagrams, do you know where to purchase it, as I think it could be a big help in the future?

Thanks for the help and your advice so far.

Matt

david2000 21st November 2020 22:58

hi matt
i have sent you a pm
david

Matt G 23rd November 2020 18:30

2 Attachment(s)
After a day of checking I found the cause of my screen remaining blank or flicking On intermittently, down to a corroded and chaffed wire ( white / red stripe Wire ) Down at the bottom of the centre console , heater metal frame (see pic- green circle)

After a soldered repair it came straight back to life, however it has now highlight I have a further electrical gremlin, around the Sat nav drive box, which I am yet to resolve, it occosionally works, so back to wiring again.

But at least I have a screen ,radio, tape and cd drive on

Also in relation to JB tourer having his joint of wires underneath the driver seat, mine did not. I found them (purple /pink ) all soldered together behind the centre console along with a bunch black wires, so assuming as my car is a mk2 it may have been a modification by Rover on the later cars. See pic - red circle

I hope this may help someone with a similar problem in the future

Matt G 24th November 2020 22:04

Sat Nav issue resolved, turned out to be the corroded 6 pin cable inside the Sat Nav Drive as well documented on the forum


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