Expert: Peter G. Lee - 9/2/2006

Question
I bought a used 94 infiniti in good condition.
I am having a problem with some of the electrical my low beams do not come on but i have high beams which both work and stay on. I also do not have power to the main radio CD/tape player. The speakers make fuzz noise but very quiet no sound. I have checked the fusiable links along with the passenger compartment fuses. none of them are blown or damaged?

Answer
Hi There
I think you may have as many as three different problems.
As it say in my profile, I am in Europe (a Brit' in Spain) so American cars are rare here and I cannot answer question specific to them, only in general, so here goes.

I know it sounds stupid but have you checked the bulbs? It’s caught me out more than once missing the obvious.
Other than both dip beams being blown it could be a relay or the dip switch, testing with a test probe or a meter set at 20VDC is the only way to check it out.
If you have no power to the head unit then it’s not surprising there is no sound, get the problem with the head unit sorted and it may sort the speakers out too. I attach below a copy of the idiots guide to radio installation, it might help you establish the basics and eliminate the problem with a bit of luck.

Basic test and diagnostic procedure for car wiring harness.You will need the following;

A test meter set at 20vdc or a test lamp (two wires on a 12v bulb) or probe (like a screwdriver with a 12v bulb in it and a lead and clip)
Some masking or paper tape to label wires and a marker pen,
An “AA” or “AAA” torch battery, (or borrow one out of the TV remote for an hour)

First the easy stuff, the speakers, (without amp!)

Speaker wires.
These are normally twisted together in pairs if you are lucky and are the same colour for each pair but one with a colour trace on, i.e. blue and blue/white, green and green/white. Touch a pair across the battery and you will hear a noise on the corresponding speaker, label it (e.g. left rear), continue until all four are identified and labelled.

Power leads connector.
Earth one side of your meter or tester to a metal part of the car, probe each wire until you have a wire that is live all the time with the ignition OFF, label this ‘+30’.
Switch on ignition and redo test until you find another previously dead wire now live, this is ‘+15’.
Switch off ignition and switch on the side / park lights, repeat test until you find a third live, label this ‘lights’. Switch off the lights.
You should now have two or three left. One will be earth, (usually black or brown); one could be to an amp and or electric ariel (usually blue or blue white) and one for phone mute if fitted. Clip tester to +30 and probe one of the remaining wires, if you have an electric ariel it will go up. Connect your DIN plug to the correct wires and jobs a good un’.

DIN connections are.

Speakers

Right rear -,  right front -,   left front -,  left rear-,
Right rear +, Right front +, left front +, left rear +

Power block viewed from cable side

Phone mute (white),/   n/c, /      ariel & amp (blue), /ignition (red)

N/c, / 12vlive, (yellow or orange), / lights, (various colours),/ negative (black)
Hope that helps, Peter