Online Car Stereo Trouble shooting & repair service.

Owner Operated with over 35 years Car Stereo Experience.

The following is a list of car audio questions that we get asked all the time.

You may be able to fix your car audio problems with this advice.

If you can not find the answer here, then Email for Mobile Car Stereo Enquiries.

Advice is free.

Nearly all car audio systems (head units) available today are Euro din size and can be installed into most modern cars, replacing the existing (Din) factory system and using existing mounting brackets or the Din sized mounting sleeve. Filler custom pockets are also available from us if required for filling that double sized hole.
Custom replacement dash fascia and fitting kits are also available for almost all vehicles. Email for Mobile Car Stereo Enquiries.

Some people will be able to attempt a full install. This should only be done with the knowledge that all manufactures warranties may be voided if a mistake is made in the installation process, just one wrong wire connection can mean a non warranty repair bill, even for your brand new out of the box car stereo system. The vehicle electronics may also be damaged.

We recommend you call our professionals for advice. Not only will you save time, but you can also save money. Custom brackets and plug to plug wiring looms to suit most vehicles are available from us.

All vehicle manufactures unfortunately use different colour coded wiring and different configuration loom connector plugs. This can even vary from model to model even within the same make of vehicle. Don’t guess at these, see “doing it yourself”, and seek professional advice. Custom converter plug to plug wiring looms are available from us for plug and play solutions.
Iso standard colour codes for stereo units are as follows,

GREEN = Left rear speaker positive.
GREEN / BLACK = Left rear speaker negative.
PURPLE = Right rear speaker positive.
PURPLE / BLACK = Right rear speaker negative.
GREY = Right front speaker positive.
GREY / BLACK = Right front speaker negative.
WHITE = Left front speaker positive.
WHITE / BLACK = left front speaker negative.
RED = ACC power 12volt (switchable).
YELLOW = Battery back up power 12volt (permanent).
BLUE = 12volt output to switch the antenna or amp on.

Most original fitment speakers are compatible with new stereos. (Apart from some Bose systems), Speakers are of four ohm impedance (industry standard) but may be under rated in power handling. Connect them and listen, if you like the sound at your usual listening levels, you will save time and money, so do not need to replace them. If the sound is lacking, check the wiring for faults or upgrade speakers as necessary.

Please note that buying 200Watt speakers WILL NOT give you a more powerful system. The power is governed by the stereo output, not by the speaker rating. Replacements can be done at any time, if and when the budget allows.

Tip: Be wary of new speaker depth when installing in doors (your wound down window has to fit in there as well)

Speakers all need to push air at the same time, if one pushes and one pulls, then the bass is sucked away. (out of phase) Speaker terminals have + and — (positive and negative) and must be connected similarly to the stereo amp or head unit, + to + and – to –. (similar to battery terminals).

To test speaker phase.

Turn the balance from centre to right speaker then through centre to left. If the base disappears in centre position, then reverse + and – on one speaker only. So both speakers now push at the same time.

We have adaptors available to suit most stereo systems. Some have direct input into a rear RCA AUX input or use the CD Changer input, others are connected directly through the aerial input lead.  (These are not prone to interference as some other FM Modulated transmitters are.)

Bluetooth AUX adaptors are a great add on and provide wireless music streaming from your phone to your existing stereo. They can be fitted to most existing stereo systems where a replacement stereo is not an option.

*Check car fuses and fuses behind the stereo. All modern systems require two. (One to retain memory of stations and settings, and one to turn the unit off when vehicle is not in use.)
*Is the stereo coded? Re-enter the correct code.
*Check speaker wiring for short circuits and shorts to earth on speaker terminals. (Terminals must not touch any metal parts on the vehicle!)
*Use the reset button

Re-enter the known code. If the code is not known, don’t guess it! It can permanently lock up the stereo and make it non repairable. If the code is not known and you have proof of ownership call the vehicle manufacturer as they may have the correct code on file.

Push the reset button on the fascia of stereo and also the on the changer, or unplug the unit and then reconnect after 60 seconds.
Sometimes holding the Eject button for 5 seconds can work also.

6 Disc players can only be effectively repaired by an experienced technician. They are very complicated and there are no shortcuts. Don’t add to the repair cost by trying to fix it yourself.

Replace the lead to see if there are any broken wires in the old one.

See iPhone-iPod-accessories

The Entire dash face can usually be changed for a new one that fits perfectly and has a standard sized hole to suit the new standard Din stereo of your choice with all the added features you require. Use our search button on our front page to see what is available for your car or Email for Mobile Car Stereo Enquiries.
Most dash kits are now available.

You also have the option to have a Bluetooth AUX system fitted to most existing systems at a very reasonable cost.

Our recommended and newest expanders change the frequency by a factor of 10 and 20 automatically as no expanders can change the numbers displayed on the stereo as they are factory set. So to listen to 98.2, tune to 88.2. and (85.4 is 105.4) easy. This allows all stations from 88.0 to 108.0 to be received.

We also have USA to NZ expanders that change the recieved frequencies by .5 Mhz.

Some vehicles require a booster amplifier to power the standard car aerial (giving improved reception) and these can be purchased separately or incorporated into our quality band expanders. you have a BMW (E46) or MINI between the years 2000 and 2009 we can re program most of these stereo’s to full NZ specifications. (Including correct number display)

All other vehicles can be converted with our quality FM Band expanders, with built in aerial amplifiers to enable the FM radio to receive all NZ stations within range.
All band extenders change the frequency received but can not change the numbers displayed.

See car audio accessories

To comply with the new New Zealand driving and cell phone laws you must have a hands-free operation if you text or make and receive calls while driving.

If your phone is “Bluetooth enabled” then a hands-free kit is the answer. This enables you to receive and make calls (by the push of only one button) to anyone you have stored in the phone’s memory. See our Bluetooth product accessories page for more info.

Upgrading your car stereo system is also an option. See “Bluetooth enabled car audio” options on our products page.

Upgrade your stereo and have the best of both worlds with better stereo sound, and hands-free for phone calls heard through your stereo system while wirelessly connected to your phone. This also means music stored on your device can be played through the stereo as well via wireless music streaming.

A small recessed switch usually located on the front panel of the stereo (the size of a pin head) so very hard to see. This button re sets the stereo’s brain to factory settings.
Use a paper clip to gently press this hidden reboot button.

If no re set button is obvious then disconnecting the battery for five minutes can also sometimes work. Be sure to do this with the ignition key removed while disconnecting AND reconnecting of the battery terminals. Also take note if the stereo is coded as you will need the CORRECT code to be entered after re connection.

This is usually caused by bad solder joints or blown dial bulbs.
It could also be a broken flexible circuit board on flip down face stereos.

Check the balance and fader controls (reset them to the center position). Is it one or all the speakers?
Check the wiring for breaks and short circuits, or bare wiring touching the metal of the car.
Call our radio technician to test the system, or replace any faulty speakers.

Check the aerial (is it fully extended?) is the lead broken or disconnected from the stereo? Check the aerial amp wire (for windscreen and stubby roof aerials) is it connected and has a 12 volt feed. All OK? Then there is a possible internal tuner fault or the wrong band expander for the vehicle has been fitted?

Some vehicles require a power lead to power up an internal aerial amplifier. Is that connected?

If the reception is OK on AM then it is usually an internal tuner fault.
If there is no AM reception as well, check the connections, is the aerial plugged in? See the notes above.

Call Auckland Mobile Car Stereo, Ph: 021-935-374 or 09-444-5883 for Mobile on site service at your home or work within the Auckland metro area.


If the unit accepts CD momentarily and then ejects, then the problem is usually in the laser lens, being dirty or too weak and unable to read CD information.
If you can not hear the CD spinning then it is possible that the motor is faulty.

Try the reset switch.

Leave the tape or CD in place and do not try to remove it.
To force tape or CD removal can more than double the repair cost (replacing broken or bent mechanism parts as well as removing the jammed tape or Cd)

Seek professional help on this. Specialist knowledge and tooling is essential.
In some instances metal cut from a vehicle can alter the strength, and therefore the safety of that vehicle. Enlarging a cavity to accommodate an oversized speaker may render your vehicle unsafe and therefore unwarrantable. (no warrant, no insurance, and also unsafe and not legal to drive on the road).

Automatic aerials can usually have the broken “mast only” replaced (no need to replace the motor as well). The mast only option is very cost effective, sometimes being less than 1/4 of the cost of a total aerial replacement.

We also have electronic stealth aerials that adhere to the vehicle windscreen and therefore can not be broken again.

Contact us. Email

For some custom manual aerials (& after market aerials) buy better through this site than through a car dealer parts department.

Help with fitting can also be provided.

There are a limited number of 24volt stereo units made.
I suggest a 24 to 12 volt converter that will enable you to add any standard 12 volt stereo to a 24 volt system.
Be sure to get one that has two inputs and two outputs (for back up and switched power) and can handle the power draw. Enquire at

Sub woofers handle the lowest bass (20hz-80hz), woofers would handle the bass chores, mid ranges would handle the frequencies above that, and tweeters are sent frequencies in the highest ranges (about 5khz and above).

In a standard car audio system, you will usually find a single speaker trying to handle the entire frequency range by itself (although sometimes it’s broken into a 2-way design, with a tweeter sitting on top of the main speaker). The reason that this doesn’t work well is that the physical properties that make a speaker good at a certain frequency range make it bad in another frequency range. For instance, a sub woofer is good at moving very large volumes of air with it’s large cone area and heavy mass. But that heavy mass prevents it from moving quickly enough to handle the high end frequencies.

Sometimes just adjusting the tone controls to what you like in music is a good step and all the improvement needed. Hope that helps.