[Sigmavsop]

Hi I am trying to restore a 1991 Chevy Camaro Convertible for my daughter and I am wondering how to repair the passenger side power window since it will not go up or down. Also I would like to know what will cause the cigarette lighter to continue to blow fuses every-time something is plugged into it.

 

[docvette]

Doc here, imp:

Is it just the one window?

Usually , the switches go bad..

To test pull the door panel carefully, and meter the plug at the motor, use a DVOM for checks set to DCV, VX50 or higher, and locate the your up and down wires on the motor, ground the meter to the BODY, and probe each wire while someone activates the switch..you should get 12 VDC in the up, and 12 Volts in the down..If not suspect the switch,

To test the motor, place 12 volts from a jumper to the up terminal and ground the motor ground, and the same for the down..it should move accordingly in each direction.

As for the lighter, If it only blows fuses when something is plugged into it, Suspect the socket, center terminal. In the very back of the unit is a connector (one wire) that may be hitting a ground when something is pressed against it..at any rate, those are like $5 bucks at auto zombie on the "HELP" tree..you can just replace it fairly easy and cheaply..

Doc imp:

 

[dmorris1200]

Actually when you are checking power windows in most late model cars you should always disconnect the connector to the window motor and put a digital voltmeter across both terminals in the harness connector, not to body ground. If you look at the sample schematic you will see that the window switch provides both ground and power to the motor. The switch swaps power and ground back and forth depending on what way it is pressed. The circuit does not ground through the motor body to the door frame. I have seen many times where the switch provides power both ways but lost ground due to a poor connection in the switch on the ground side. If your meter was connected to body ground it would still show 12 volts but if connected to both of the connector pins it would show no voltage if the ground side of the switch was bad. By connecting both leeds to the connector it assures both a good ground and a good power source. When operating correctly your meter should go from +12 volts to -12 volts as the switch is toggled back and forth. The absolutely best way to do any electrical work on any car is to always check a wiring schematic first to see how the circuit works.

 

[docvette]

Doc here, imp:

DMORIS1200,

Hey! Haven't seen you around in a long time..couple of Years? Maybe?

On the Grounding of the meter, I specified the body ground only to verify power through the switch only..To verify the switch is actually working..That is why I specified use a DVOM only..so you don't get a damaged movement on a reverse polarity..instead just a big "-" on the readout and 12 VDC reading..

To verify the ground multiplexing , yes, you in fact do need to go to the plug with Both probes , but it won't show if the switch itself is defective.

Have a happy Thanksgiving!

Doc imp:

 

[dmorris1200]

To verify the ground multiplexing , yes, you in fact do need to go to the plug with Both probes , but it won't show if the switch itself is defective.

Yes it will. I do this 8 hrs a day, 40 hrs a week. The switch provides both the ground path and the power side. If your meter is across the connector and you hit a switch with either a bad ground path or bad hot side the meter will read zero volts since a multimeter needs a complete path (hot and ground) to work. If the switch is good it will read full voltage. If I only had a dollar for every inexperienced mechanic I've seen try to explain to his boss why he just installed a 200 dollar motor and wasted 2 hrs of his time only to not fix the problem because he only checked for 12 volts with a grounded meter instead of verifying power and ground both ways across the connector. Customers love the call back from the service writer too,lol. If part of the switches job is to provide a ground path to whichever terminal isn't hot and then switch that polarity to make the motor go in the opposite direction why wouldn't you want to check that as part of your test? Once again, the motor does not provide a ground so the switch must provide that ground at the same time it provides power. It is one of the most commonly misdiagnosed jobs dealing with younger inexperienced mechanics, and believe faulty power windows are a fairly common repair in shops.
So again in summary, with multimeter (DVOM) across the connector if it switches from positive to negative 12 volts when the switch is toggled the switch is doing its job. If either part of that switch isn't working correctly the meter will read zero when the switch is depressed since a meter can't show 12 volts without power and ground. It is a simple accurate test.

Happy Thanksgiving! Yes it's been awhile.

PS. One last thing I will add to try and help those of you who don't routinely read schematics and do these checks every day is that a cars power window switch is not like your average on/off switch. It is much more involved. A on/off switch simply interupts a connection. A window switch has it's own 12 volt feed and a ground wire (usually black) connected to it. It must have the ability to not only apply power to one output but at the same time apply a ground to another, and then do the oposite when the switch is toggled the other way. Look at the schematic I posted closely in my first post and you can see this. If the ground (black wire) out of that switch is broken the switch cannot provide a ground to the motor and it will not work even though it has 12 volts going to it.

 

[dmorris1200]

Well wouldn't you know it. I go to work today and what do I get, a repair order for a late model Suburban with a drivers window that doesn't work. I popped off the door panel, unplugged the window motor, then connected my meter across the harness connector as shown in attached picture. Pardon the lousy quality of the pictures but all I had was my camera phone. One touch of the switch one way produced +12 volts as shown in picture. One touch the other way produced -12 volts as shown in picture. So in a few seconds and just pressing a switch twice I verified that I had power and ground functioning both ways at the motor connector. If there was a fault in the circuit anywhere my meter would have read 0 volts when the switch was depressed for Up, Down, or both (depending on where the fault was) because it would have been missing either power or a ground path to complete the circuit. I priced out the motor, my service writer sold the job, and a few minutes later she was fixed. Quick and painless, just how I like it.

PS. Doc please understand I do not wish to belittle the amount of time you spend trying to help people you don't even know. You have helped many. At the same time doing this for a living I felt the need to point out the chance for error with your procedure and show how we would train a new technician learning the ropes. The beauty of electrical diagnostics is even with the best method for testing there is always some margin for error. If the circuit has a corroded terminal causing a poor connection but not a complete open with a DVOM you could still read 12volts due to the high resistance of the meter. Since there is almost no current flow through the meter it doesn't act as a load. As soon as you add a load (window motor, headlight, starter, etc.) the circuit fails due to it's inability to flow enough current through that corroded connection. Have seen this with trailer light issues. Unplugged you'll see 12 volts with a meter, then you plug in the lights and they don't work. Then after a little digging you find that corroded wire behind the bumper. Electrical diagnosis over the internet is a challenge and I give you credit for having the patience to help people with it. I unfortunately don't have that much patience so please don't take anything I have said personally if I came across a bit rough.