FAQ's - Common Questions asked by customers of Trends Hamilton.

Will my new car stereo system fit in my car?

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 and custom fitting kits (if required) are also available from us for filling that double din or unusual sized hole (very often the case with imported cars). Custom replacement dash facials and fitting kits are also available for almost all vehicles.

Can I do it myself ?

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!

Some insurance companies may deny an insurance claim unless installation have been done by a qualified installer - especially car alarm installation. 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.

What are the wiring colour codes for stereo units and vehicles?

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 brackets and plug to plug wiring looms are available from us for plug and play solutions.

Should I replace the car speakers as well?

Most original fitment speakers are compatible with new stereos. All apart from some Bose systems, 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.

If the sound is lacking, check wiring for faults or upgrade speakers as nessessary. This can be done at any time, if and when the budget allows. Be wary of speaker depth when installing in doors (your window has to fit in there as well)


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 un warrantable. (no warrant, no insurance, and also not legal to drive on the road).

I Have no bass sound in speakers?

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

I think my Stereo is dead? / No Sound.

Check car fuses and fuses behind stereo. All modern systems require two. (One to retain memory of stations and settings, and one to turn unit off when vehicle is not in use.)*Is the stereo coded?

Re-enter 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 reset button 

My Stereo has a code?

Re-enter known code. If code is not known don’t guess it! It can permanently lock up the stereo and make it useless. If code is not known and you have proof of ownership we can decode or re code most units for you! 

Where can i find my Reset button?

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 paper clip or ball point pen to gently press.

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 disconect AND reconnecting of battery terminals. Also note if the stereo is coded as you will need the correct code to be entered after re connection.

Why can’t I see see my Display or any numbers?

Usually caused by bad solder joints or blown dial bulbs). Can also be broken flexible circut board on flip face stereos.After trying reset and checking fuses Send to us for repair. 

My CD changer or stacker is jammed, what do I do? 

Push reset button on facier of stereo and also changer or unplug unit then reconnect. Sometimes holding the Eject button for 5 seconds can work also. No luck? Send to us for repair. 

Why am I getting Distortion / no sound from my speaker/s?

Check balance and fader controls (reset to center). Is it one or all speakers?Check wiring for breaks and short circuits or bare wiring touching metal of car.Call our radio technician to test system, or replace any faulty speakers. Possible internal component failure. Send to us for repair.

Why do I do if I have No AM radio reception?

Check aerial (fully extended?) lead broken or disconnected from stereo? Check aerial amp wire (for windscreen and stubby roof aerials) is connected and has 12 volt feed. All ok? Possible tuner fault.Bring into us for repair.

Why do I have no FM radio reception?

If reception is ok on AM then send to us for repair as it is usally an internal tunner fault. If no AM reception as well, check connections, is aerial plugged in? See notes above.

I have a broken car aerial / antenna, can I fix this?

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 the cost of a total replacement.

For custom manual aerials, & after market aerials, buy cheaper through this site than through a car dealer (genuine?) parts department. Help with fitting can also be provided.

How Can I play my iPod through my existing stereo?

We have adapters available to suit MOST STEREO SYSTEMS. Some have direct input into the rear AUX input or use the CD Changer input, others are connected directly through the aerial input lead. All charge iPod and iPhones while in use.

These are not prone to interferance as other FM Modulated transmitters like are. Adaptors are also available for the NEW iPods & iPhones to allow charging while in use. Just plugs onto your existing lead.

How do I receive all NZ radio stations on my Japanese car stereo?

If you have a BMW (E46) or MINI between the years 2000 and 2007 we can re program most of these stereo's to full NZ specifications. (Including correct number display) All other makes and models can be converted with our quality FM Band expanders with built in aerial amplifiers to enable the FM radio to receive all NZ stations.

All band expanders change the frequency received but can not change the numbers displayed.Our recommended expanders change the frequency by a factor of 10. eg. to listen to 98.2, tune to 88.2. easy.

My new iPod will not charge on my existing lead?

iPod have had 12 volt charging on all their units up untill they changed to 5 volt on their new models of iPod & iPhone.We now have adaptors to rectify this problem. A converter that plugs straight from your old lead to the bottom of your new iPod. Problem solved!

The latest generation iPod and iPhone's now use a different charging system (now 5 volt). We now have an adaptor that just plugs into your old lead and converts it to the latest charging system.

What is the best way to allow the hands free use of my phone while driving?

To comply with the new New Zealand cell phone laws a simple bluetooth microphone is the most cost effective. If your phone is "Bluetooth enabled" then a portable hands free kit is the answer.

This enables you to recieve and make calls (by the push of only one button) to any one you have stored in the phones memory and you can take it with you from car to car or even use at home or in the office. Upgrade your stereo and have the best of both worlds with hands free phone calls heard through your stereo system.

Do you have 24 volt stereos?

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 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.