All power windows don't work. fuses ok. replaced master power window switch and still doesnt work. could it be a bad relay somewhere? thanks!
Assuming you have checked all fuses within your car. Remembering not just the fuse box under the hood, but also the fuses that are underneath the dash / steering wheel on most cars.
Is this a common fault? ie did the stereo and the power windows both stop working at exactly the same time. For example fix one and the other will be fixed as well.
Does the car start? if so you have your 12 volt ignition control circuit working. This circuit creates a pilot circuit ie once energised it is used to drive power to the coils of various relays to allow a switch to be automatically moved and allow power though to accessories such as stereo, windows etc. This all happens in the blink of an eye when you turn your car key.
Make sure the ignition is off and check the most simple things including fuses under hood and under steering wheel, check all wiring looms, make sure all relays are securely in their positions. Check for moisture on leads and relays, check all connectors and also check for corrosion. Look for any obvious damage to wiring.
What we need to establish- is power reaching the motors for your windows ? we can use a test light or multimeter set to Volts DC. If using a test light, make sure the light works first, same if using multimeter, put it across the battery terminals the point of the tester goes onto the active terminal of the battery and the lose wire goes to somewhere metal on the car for negative earthed cars, (most cars are negatively earthed.) Something like a screw or bolt that connects the cars panels to the frame for example should be fine. Experiment with best point to connect your lose wire so you know you are using the tester correctly.
Is there a fuse for windows ? if so make sure ignition is turned off, remove fuse, turn ignition key to on/run to whatever the last point is before your starter motor turns over. Now check for power within the fuse holder to see if power is actually getting to the fuse. If not then work your way back it is probably a wire loom connector or relay. If power is there then turn of ignition again. Put fuse back in and then go to next step.
Remove the cover for you window switches, turn ignition key to run just before starter motor turns don't start the car and now have a tinker with the tester or multimeter to see if power is actually making it to the switches. Use the switch, is power getting to one side when not activated, then when activated is power getting through to the other side of switch. If yes then work your way forward on the wires to the next point, probably the motor. Is power getting to the input of the motor ? if yes then check connections of wire to motor.
If No power getting to window switches then work your way back.
Failing the above working. Next thing to do is check relays - first identify which one controls the windows and accessories etc. Very handy to have a wiring diagram. Without a diagram Not always easy to identify where or which relay to check I know, often with someone turning the ignition key and listen to the relays you will hear the relays click. Again relays are under the hood and often on some cars under the dash / steering column area. Make sure you are clear of any moving parts under the hood when you check this, your friend wife/partner will inevitably turn the key too far and scare the **** out of you when they turn the engine over and we all know engines can bite, those fans have friggen big teeth. ( speaking from near miss experience here !) Avoid turning the engine over - just turn the key to accessories on and off to hear the clicking of relays. Remember some cars electric windows need the key turned to on/run which is the last point before the start motor turns over.
If you can't identify the relays clicking over or not, you can remove them but only do so with the ignition off. You can make up some small wires to attach temporarily to just the coil of the relay .You can use these temporay wires to connect the coil direct from the battery to see if the coil is energising, if the coil does energised use a multimetre in resistance mode or in continuity test mode to see if the contacts /switches of the relay are working properly. If the relay is working fine Make sure you put the relay back in its correct holder.
Once you have identified if the relay is clicking on properly or not follow this method.
A lot of relays have diagrams of where the coil lead power connector is and also where the NO ( normally open) NC Normally closed connections are. You may use a multimetre, or test light to check if power is reaching the input side of the relay if no power work your way back along the circuit. You will need to have the ignition turned to on/run to the last point before the starter motor turns over do not turn the starter.
You may also be lucky whereby a faulty relay can be found by there being two or more identicle relays that are used for different things through your car. Make sure you label them somehow maybe with masking tape and writing on them so you know where each one goes back into if you take them out. Often I have taken one known working relay out from a different part of the car and swapped it with another one the same to see if the known working circuit has stopped working. This can get confusing though because it is easy to chase your tail and coinfuse the hell out of yourself, especially if you are not a technician.
My first instructor taught me this for fault finding . KISS meaning Keep it simple silly ! dont look too deep into things at the start otherwise you shall confuse yourself.
Jun 03, 2011 |
Car Audio & Video