Car audio - bridging permanent live & ignition live

Reesy

Hi,

I replaced the worn-out Pioneer stereo in my 1991 Mk 1 MX5 today with an Aldi / Tevion stereo. The wiring had been done by a real bodger - one speaker wired back to front & lots of wires twisted together. To fit it, I had to replace the old Pioneer harness with a DIN harness.

Anyway, on this car there is no sign of a wire bringing live current from the ignition (i.e. only on when the key's turned). The old stereo was wired with the permanent live & the live thru the ignition both bridged together & joined to the permanent live feed. Given that I haven't the skills to wire a new live thru the ignition, I replicated this for the new harness. It works fine except, like before, I have to remember to turn off the stereo when I turn off the ignition.

Anybody know of any problems that this wiring might cause me in future?

Cheers

Plug

They hardly gave a wiring list in the package showing what pin numbers are etc? The radio should have a constant live and an ignition live.

nogoodnamesleft

How do you know that there is no iginition feed?

Have you tested with a mutimeter to see what is what in the wiring harness?
Vehicle wiring schematic diagram should be easy to find on the web with the MX5 fan base. Should tell you what colour cores are what.

The Aldi stereo should have a wiring diagram also to aid install.

colm_mcm

YOu can get an ignition live from the cigarette lighter

Reesy

Hi guys,

They did give a wiring diagram with the stereo but the issue is that there is no ignition feed wire available from the car side. The harness in the car was a Pioneer one (again, I had the wiring diag.) with the red & yellow both connected to the permanent live in the car.

Thanks colm_mcm, that's a good idea. Next time I'm at the car with a decent bit of daylight I'll take a live from the cig lighter (or similar).

Plug

colm_mcm wrote: »

YOu can get an ignition live from the cigarette lighter

Thats constant live there.

Reesy wrote: »

Hi guys,

They did give a wiring diagram with the stereo but the issue is that there is no ignition feed wire available from the car side. The harness in the car was a Pioneer one (again, I had the wiring diag.) with the red & yellow both connected to the permanent live in the car.

Thanks colm_mcm, that's a good idea. Next time I'm at the car with a decent bit of daylight I'll take a live from the cig lighter (or similar).

Your best bet is to connect into the ignition wiring direct
Remove the cowl from around the ignition unit - it is probably held held with a few Torx type screws or philips - and remove the bottom / lower dash panel for easier access..

Use a 12 v tester lamp to test the circuits to the ignition - ideally at the block / multi connector from the ignition unit...

You need to test each wire making a note of which circuit / wire is live when the key is on - and off.. Obviously you are looking to identify a wire that is only live when the ignition is On.. and goes dead when you switch off.

Then connect your main power lead to that identified wire ... Connect an in-line fuse in to that wire ... supplied in your kit no doubt - but if not, you can buy them a motor factors for about 50 cent.

colm_mcm

Cig lighter would be ignition live. Ive never seen one that works with the car off.

There should be one there on the radio loom already though.

Reesy

colm_mcm wrote: »

Cig lighter would be ignition live. Ive never seen one that works with the car off.

There should be one there on the radio loom already though.

Yeah, like I tried to explain, there isn't. At least it's not visible.

Thanks guys. Should be easy to test. If the cig lighter is easy enough to get to the back of, I'll try work it with the key out. Guess the fuse current should be high enough on the cig lighter, too.

colm_mcm

The terminal at the middle on the back of the socket is the one you're after.

Reesy

Thanks Colm_mcm,

Just tested the cig lighter & yes it goes thru the ignition on my Mk1 Mx5. The spare inline fuse that I have is 25A not the 10A that the fuse in the back of the stereo itself is rated at, so I'll get the right fuse before I start. Looks like an easy-ish job, even for me. Cheers.

Reesy

Guys, just to close this off: in the end I didn't get around to running a separate ignition feed, and found that the radio flattened the car battery until I (recently) fixed the ignition feed, running it from the cigarette lighter.

Thanks again for your help guys.