Geekzone: technology news, blogs, forums
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.

27 posts


Topic # 57741 23-Feb-2010 13:07
Send private message

I bought a car stereo, and I've been trying to get the thing to show any signs of life. One of the previous owners has butchered the wiring, so I decided to give wiring it up a try. I've checked google for wiring diagrams and so forth, and as far as i can tell...i have the car wiring attached to the ISO connector in the correct way. Only problem is, the head unit doesn't power up.
Either the wirings wrong or the head unit is a dud. Any suggestions on how i might go about testing both scenarios? I have a multimeter around here somewhere, what leads should I be testing?


Create new topic
2865 posts

Uber Geek
+1 received by user: 262

  Reply # 301461 23-Feb-2010 13:11
Send private message

More info on the actual unit you are trying to install and make/model of the car may help.

27 posts


  Reply # 301462 23-Feb-2010 13:14
Send private message

1990 Toyota MR2, Domain Head Unit DM-B528MP. The head unit wiring ends in a standard ISO connector.


1623 posts

Uber Geek
+1 received by user: 276


  Reply # 301584 23-Feb-2010 17:04
Send private message

Fastest way to check is get another head-end and plug in. There are so many connections - even for 12v, 12v stand-by, 12 v accessory, it can lead to a crazy head case situation. You mentioned butchered wiring - is that on the ISO wiring or the head unit ? Either way, it will end in tears. Lots of tears.... and blown fuses, smoked wiring looms, and carcked speakers.
You may even be able to take the head end into a car stereo installer place and get them to test it - maybe for a small fee. Probably would be the fastest way.

My thoughts are no longer my own and is probably representative of our media-controlled government

473 posts

Ultimate Geek
+1 received by user: 2


  Reply # 301600 23-Feb-2010 17:59
Send private message

standard iso wiring= yellow fulltime, red accessories, black earth ( negative )
inplug the iso wire get a multi meter or test light, if neither available use a 12v bulb connected to wire, test each of the car looms wires seperatley, earth to a metal part of the dash or somewhere you know it is earthed. It could be the fuse has popped on the fulltime (positive) wire

1475 posts

Uber Geek
+1 received by user: 41


  Reply # 301624 23-Feb-2010 19:32
Send private message

I always find this site handy:

It has most vehicles listed with wiring diagrams etc.

544 posts

Ultimate Geek

  Reply # 301635 23-Feb-2010 19:59
Send private message

Ah yes. The MR2. They're fun.

Now, from memory, the colouring of the wires is standard across the board for Toyota's of that era.
If you can find a diagram for that, and match it against your new headunits diagram, you should be sweet.

Btw, the MR2 has a factory 8inch sub, for which is has its own amp which is located in the side panel on the passangers side. The amp from memory is a bit funny with headunits. I think it only works with the factory one.
Luckily, because the cabin is quite small, a couple of 6x9's will give a good bass sound.

71 posts

Master Geek

  Reply # 301641 23-Feb-2010 20:10
Send private message

easiest way i found to test the headunit.

wind/tie/knot the 12v constant and 12v acc wire together on the headunit wireing harness, find a suitable earth, and touch the two wires to all the wires coming out of your car for your headunit.

repeat once with ignition off (to find constant)
and again with the ignition on (to find acc power)

27 posts


  Reply # 301644 23-Feb-2010 20:25
Send private message

Cheers everyone for all the advice, after some fiddling I managed to get power to the head unit. The wire for the ignition switching doesn't appear to work, so for now I've tied both into the battery line. This means i have to manually turn the stereo on and off, but its working. I've been tying all the car's wiring into a pair of standard ISO plugs, so hopefully no current or future owner of the car will have to do this again.

473 posts

Ultimate Geek
+1 received by user: 2


  Reply # 301678 23-Feb-2010 22:03
Send private message

rassnor: Cheers everyone for all the advice, after some fiddling I managed to get power to the head unit. The wire for the ignition switching doesn't appear to work,

Blown Fuse, test light or multi meter your fuse box

2114 posts

Uber Geek
+1 received by user: 627


  Reply # 301929 24-Feb-2010 22:14
Send private message

Does the clock work? If not blown dome fuse. As Adam said, some of the MR2's had an active audio system, all speakers were amped, amps are behind the panel under the passengers seat belt. It was a 4in sub from memory. I rewired mine from the ground up when I had it, put in some decent 12gw direct to the battery and a decent fat earth.

Create new topic

Twitter »

Follow us to receive Twitter updates when new discussions are posted in our forums:

Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:

Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:

News »

Intel reimagines data centre storage with new 3D NAND SSDs
Posted 16-Feb-2018 15:21

Ground-breaking business programme begins in Hamilton
Posted 16-Feb-2018 10:18

Government to continue search for first Chief Technology Officer
Posted 12-Feb-2018 20:30

Time to take Appleā€™s iPad Pro seriously
Posted 12-Feb-2018 16:54

New Fujifilm X-A5 brings selfie features to mirrorless camera
Posted 9-Feb-2018 09:12

D-Link ANZ expands connected smart home with new HD Wi-Fi cameras
Posted 9-Feb-2018 09:01

Dragon Professional for Mac V6: Near perfect dictation
Posted 9-Feb-2018 08:26

OPPO announces R11s with claims to be the picture perfect smartphone
Posted 2-Feb-2018 13:28

Vocus Communications wins a place on the TaaS panel
Posted 26-Jan-2018 15:16

SwipedOn raises $1 million capital
Posted 26-Jan-2018 15:15

Slingshot offers unlimited gigabit fibre for under a ton
Posted 25-Jan-2018 13:51

Spark doubles down on wireless broadband
Posted 24-Jan-2018 15:44

New Zealand's IT industry in 2018 and beyond
Posted 22-Jan-2018 12:50

Introducing your new workplace headache: Gen Z
Posted 22-Jan-2018 12:45

Jucy set to introduce electric campervan fleet
Posted 22-Jan-2018 12:41

Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.

Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.