Hi folks,

I thought I'd written a blog entry about it, but maybe not as I can't find it either! Will have to do that!

Yes radio is a common one, remember there are two components with the radio, the head unit itself and the rear amplifier (hidden behind the rear right hand side speaker).

How did you disconnect the radio, fuse/relay in the IPM or by unplugging the head unit? My recent playing around with the head unit and amp has discovered the amp in mine has constant 12v feed to it regardless of ignition/radio state and it seems to power on and off based on a signal over the CANBUS, so depending on what way you've disabled your radio will help pinpoint the head unit itself or the rear amp.

Quick one, when keys are off/removed from ignition, wait 5 mins, then try turning radio on, will it turn on? Does it constantly show the clock?
That's one that's cropped up before due to a dodgy wiring change that forced the ignition sense to have constant 12v and so it never enters sleep.

Also, that alternator charge voltage of 12.5v to me sounds like it's not working at all! So engine off and voltage is 12.5v and with engine on/alternator running it's 12.5v too? Again I'd say disconnect the battery button sensor and try that again see if any difference. If not then I think you've got two issues, one being the alternator is shot.

 

Well I heard this morning that KwikFit are doing a free battery and alternator check. So I drove round to my local KwikFit for the test. They reported that the alternator was good but that the battery needed a good charge.
However, on the way there I noticed that the speedo isn't working and the alarm isn't working. I reconnected the radio in case the 12 volt loop through was affecting the speedo but that made no difference.
I previously disconnected the radio by unplugging both plugs at the rear of the head unit.

 

Ah ok, so charging circuit sounds like it's just low, fair enough.

Hmm, no the connectors at the back of the radio will just stop it sending the 'on' via canbus to the amp in the rear, the amp will still have it's feed to it (but in theory be in sleep) so looks like it might be the head unit itself.
There isn't anything I'm aware of that would stop speedo and alarm working when radio unplugged, I've done that a few times recently whilst working on it, driving with radio completely disconnected with no adverse effect, which leads me to believe there may be something else going on here too.
Was it just speedo non-operative or other gauges too? Did it do a dash sweep before start and if so, all gauges do it inc speedo?
Sorry for more questions and little answers, just quite a few things to narrow down, but I've got to admit this is sounding more fishy.

 

All other gauges, including rev counter and even the milometer and trip mileage are working fine. No dash sweep at all. The alarm system isn't working but the LED alarm indicator is on permanently while the ignition is on.
Edit: And I'm pretty sure my head unit doesn't have an amplifier in the rear. I checked for that a couple of months back.

 

The alarm is working again. I plugged that little ammeter into the IOD fuse holder and the alarm beeped. So I unplugged it, put the fuse back in, closed the bonnet and locked the car. The alarm LED started flashing rapidly for 16 seconds as it's supposed to. But the speedo still isn't working. I've noticed that one of the relay's is marked as 30A - Central AMP but even with this unplugged and the radio disconnected, the IOD current draw is till 0.87 amps.

 

Is the speedo needle on top or below the pin ? Reset procedure Al.

If you have used jump cables or had an alternator spike,reset anyway

 

That's brilliant QinteQ. I had to use a slightly different procedure but it did the trick and now my speedo is working again. Until you asked the question I hadn't even noticed that the needle was below the pin. I'll try to post a video on the procedure I used to do the reset.

 

My video on how to do the speedo reset.

Edit: After posting my video I found a few other videos on the same subject.

 

Just a quick update:
Opened the drivers door yesterday morning and the alarm activated. Checked the battery voltage which was 11 volts (radio is still unplugged). Tried to start the car and the engine sprung into life almost immediately?
I removed the battery from the vehicle and connected it to a mains charger in my garage. At 16:00 yesterday the charger was indicating the battery was fully charged so I disconnected the charging leads and left the battery off the car overnight. This morning it was reading 11 volts again, even though there was no load on it. I'll monitor it off the car for another couple of days but I suspect that my new battery is US.
One other point, while I've been having these power problems, when the alarm activates, usually caused by opening a door when the battery voltage is less than 11 volts, the alarm continues for a minute or so before it silences itself. Then it activates again for a minute then silence. This goes on for several minutes until presumable, the battery in the alarm runs down.

 

Aha, good work AlanC, yes I'd agree sounds like battery failure if it's not retaining charge at all.
The alarm is because of the drop in battery voltage, but sounds like it then drops too low and the alarm cuts out due to battery failure/too low voltage to power the electronics.

Glad you've got further on it, back to the shop with that battery!