4200 no radio or hazards

[Hart6]

Have had my 4200 for about six weeks now. Intermittently the radio would not work - the Info Centre fully functional other than audio options. Every now and again the disc drive would operate but still with no actual audio available. It’s now not working at all and hasn’t in a couple of weeks.

Now I have of course had a search and found multiple people with the same problem, but unfortunately they all managed to solve it by replacing the fuse at the back of the NIT. I’ve tried this and it’s made no difference at all.

Interestingly I have discovered the same problem as others - along with the radio, the hazards do not work, which I am again led to believe is normally related to the fuse at the back of the NIT.

I’m not sure where to look next - the NIT itself I am worried is faulty in some way and given the intermittency of the problem it doesn’t seem fuse-related. I’m assuming the NIT handles everything and the display unit is just display?

 

[Scaf]

When you changed the fuse on the NIT had it blown ?

 

[Gp79]

Pop the screen / display out, you might find the rear frame cracked or falling apart.
This needs to be complete as there are several circuits running through the back frame.
Had this issue (among others) on the display / NIT on my project car

 

[Hart6]

Didn’t look like it had blown, no, but I couldn’t be certain as it was one of those awkward opaque ones with the clear top.

I’ve just gone out to have a look at the display. There were indeed a few cracks in the black plastic backing plate. Removed and quickly inspected and couldn’t see any sign of broken circuits however - everything looks OK and it doesn’t look like any circuits in the plastic I was looking at. Not sure if a more detailed inspection might reveal something.

 

[Hart6]

@Gp79 I have stumbled across your thread discussing the cracked rear plate - mine appears to be similar but the four springs are in place as they should be.

 

[Gp79]

@Gp79 I have stumbled across your thread discussing the cracked rear plate - mine appears to be similar but the four springs are in place as they should be.

So long as the springs in the plastic frame make good contact with the circuit board it should be ok, the rear frame on mine was so broken the springs could not make contact hence no circuit possible

 

[Hart6]

Ah yes makes sense - mine definitely not like that. It’s strange that I have exactly the same symptoms - no audio functions and no hazards - as the many people with a blown NIT fuse, but without the blown fuse. There must surely be something related going on.

 

[Hart6]

The plot thickens. The audio functions came back to life this morning for the first time in a couple of weeks despite my attempts the previous evening. I've stopped and started many times today and it's happily coming on as it should. However, I still have no hazards. I also now have the curious symptom that around 50% of the time (determined by on/off - nothing changes while the unit is running) the (inbuilt) CD player plays very quietly - less than half the volume of the radio. But sometimes it's fine.

So I'm now wondering whether the hazard problem is related at all - possibly it's just the relay. The reason for the intermittent no audio and now low volume CD is very odd and there's not much I can do other than monitor it!

 

[Hart6]

Another update on this. Radio had been working fine all month until yesterday when I came to the car and it wouldn't attempt to start after sitting for a few days. Electrics all came on and battery fine, but no crank or anything. Got in and out to see if the pump was priming and couldn't hear it - flicked the paddles however and it happily changed gear so it must have primed, and then came to life on the next attempt. No idea what that was all about. Radio now not working again.

I've now realised looking back that I have the very strange pattern that if I attempt to start the car before all of the systems are ready, the radio will then not work for a week or so afterwards. It's as though the system goes into some sort of limited mode if the ignition is f(the mpg readout does not work when the radio doesn't, either). And whatever this limitation is, it's the same as when the fuse on the NIT blows. I also don't know what brings it out of this situation - it seems to do it randomly but only on startup (i.e. it never comes back to life or indeed goes out when driving) and disconnecting the battery has no effect.

I'm completely baffled here, and it's very frustrating!

 

[Ebenezer]

Is it something similar to needing to enter a magic code when you replace the battery? If you get it wrong, the NIT doesn't allow you to enter another code again for a period. However in your case, this sort of thing happens automatically when you start the car and if "all systems are not ready", it hasn't supplied the magic go signal somehow and initiates theblock?

Just hypothesising and have no expertise on this whatsoever...!
Eb

 

[Hart6]

Sounds plausible but I don't think a code is needed for the NIT - at least I have never needed to when disconnecting the battery!