MK1 Clio battery or H/U switching off

[jamesthebuilder]

Hi everyone, this is my first post.

I have a MK1 1.2rl and have recently fitted a new Alpine X311 head unit, with Hertz DCX100 4" coax fronts (running direct from H/U), and twin 8" drivers running from a mosfet mx4400 amp (thats all the info i can get from looking at the amp - it was a hand me down from a mate)

About a month after installing this system, the head unit would switch itself off and on again, usually after around an hour of continuous use, regardless of the volume at which it is being played. It does not seem to be draining the battery, as the car starts first time with no complaints, and a quick MMR test reads 12.6v with the engine off. The issue will often (but not always) be triggered by turning on the indicators, or selecting reverse gear (ie signal to the light clusters)

My commute is a mixture of A roads and motorway, so the alternator is getting plenty of opportunity to run the (relatively low powered) setup. I have checked the charging circuit, and seems to be fine (14.2V with the stereo blasting, headlights and heaters all switched on) I have a 3 month old Bosch S3 004 battery (53ah 470a)

I have re installed the head unit, ensuring that there are no kinks in the cables, and it all fits smoothly. I have used the OE wiring harness, but have disconnected the speaker wires that are not connected, so as not to cause a short somewhere.

I have a strong earth on the amp (directly to the chassis near the rear tow point), and the amp itself doesn't seem to be cutting out during use.

Can anyone please suggest what may be causing this issue. I had a similar problem with a more powerful system in an old ford fiesta, but in that case the battery was definitely being drained, as the car would fail to start.

I have a very basic understanding of auto electrics, but am lost on this one! I have read on this and various other forums that it could be the oe harness ground connector, or that the front speakers are drawing too much power from the HU, or that a faulty amp could be to blame, or a faulty HU. the list goes on, but i am not sure how to test for most of these issues, and don't fancy paying £80 an hour to get it looked at!

thanks a lot

Jim

 

[James28]

It could be a dodgy earth on the headunit wiring loom.
Use a multimeter and put it from a 12v source to the black ground wire and check its reading a constant twelve volts.
That's the first thing I'd check.

 

[jamesthebuilder]

Thanks james, do you mean a 12v source that is seperate from the car? I have run a multi meter from the positive terminal of the battery to the ground wire on the HU, and it reads the same as when i run it straight to the ground terminal on the battery (12.6). is it worth checking from an external power source to confirm the ground is ok?

 

[James28]

Nah you've done what I meant. If the ground was a bit dodgy, you'd get variable readings from whatever 12v source you measured from.
Not sure then I'm afraid!

 

[jamesthebuilder]

UPDATE

The stereo is now turning itself off and on again after only a few minutes use. I have ruled out any issues with the amp or the speaker wiring harness (by isolating them and the issue still occurs). My headlights are now flickering, but my battery is still reading 12.6v when the engine isn't running, and around 14.25 with the engine on and the stereo blasting.

Could it be a dodgy fuse? i would have thought a fuse is either blown or not.

i really don't think it's a loose connection anywhere, but sounds like maybe a ground loop? Would it be worth trying to replace the earth connection on the headunit? though as you can see from the previous posts, it seems pretty stable.

any help would be greatly appreciated

 

[mctw]

Might be a stupid question but have you had the battery contacts off and cleaned them up properly? And made sure theyre clamped on nice and tight obviously... It does sound like the headunit is loosing power, rather than its being overloaded...

I dont see how an earth thats linked to your headunit makes the headlights flicker, and same with the fuses, might be worth checking nothing is loose though!

 

[172lover]

did you buy the radio second hand??
any issues with the last radio in the car?

 

[MT AUDIO]

Check the continuity of your stereo earth with the indicators on, if its intermmitant earthing then you need to run a seperate earth

 

[jamesthebuilder]

Thanks for all your advise.

i replaced the negative terminal clamp (the collar with teeth that grips the battery under the plastic cap) as several of the gripping teeth had broken off.
since i had everything out and was working on the car, I also patched in a new 8AWG ground cable to the stereo harness, which i connected to a good ground in the engine bay. Having done both at the same time, I unfortunately can't confirm which fixed my issue, but it is now all working consistantly. My gut feeling is that the dodgy connection on the negative terminal of the battery was the cause, but 'belts and braces' I now have an overkill ground connection on my head unit, which is never a bad thing!

cheers
jim