help fixing trunk switch

[snwsk8r8]

i need help fixing the trunk switch in the back of my car. this is a picture of the backside of the switch.i have some knowledge in electronics but not much. the light in my trunk does not work. i bought a new bulb and it still does not work. from the harness that comes out of the car that this connects to i am getting 11.75 volts. the bulb is good becuase i have the voltmeter on the setting that makes noise for the closed circuit. so i narrowed it down to the switch itself. i took a picture and did some doodling. the red line is the path of the circuit. the yellow is where i have one probe of the voltmeter. the other end i can put anywhere on the red line to get the noise except where the blue is. to me this means that resistor is my problem. can someone with the knowledge help me pinpoint my problem so i can fix it.

thanks.

** sorry if this is not the correct section for this thread, i was not sure where to put it.

**broken link removed**

picture without doodles
**broken link removed**

 

[ericgibbs]

hi,
That looks like a power diode or zener [not a resistor] .
The white line is the cathode.

Is there a type number printed on the body of the diode.?

 

[snwsk8r8]

i am looking at it and there is a # printed on it. from what i can see it looks lke

P10
974

i am not sure if there are any more digits but thats as much as i can see. if you think there are more letters/numbers i will unsolder it.

thanks

 

[ericgibbs]

i am looking at it and there is a # printed on it. from what i can see it looks lke

P10
974

i am not sure if there are any more digits but thats as much as i can see. if you think there are more letters/numbers i will unsolder it.

thanks

hi,
Does your voltmeter have a resistance [ohms] measurement function.?

If yes, measure the resistance across the diode and then reverse the meter leads and measure again.
One way you should get about say 1000hms the other way almost inifinity.

 

[snwsk8r8]

this would be the setting, correct?
**broken link removed**

with that setting, one way it come up about ".605" and the other way it continues to show "1."

 

[ericgibbs]

this would be the setting, correct?
with that setting, one way it come up about ".605" and the other way it continues to show "1."

hi,
It looks a though the diode is OK, as a double check switch to the "2K" on the meter position and say what you get.

 

[snwsk8r8]

with the meter on the 2k position it continues to show "1." just as it would with the leads touching nothing. i switched them and its still shows "1."

 

[ericgibbs]

with the meter on the 2k position it continues to show "1." just as it would with the leads touching nothing. i switched them and its still shows "1."

hi,
It looks as though diode could be open circuit.
Ive tried to identify the diode from that number you posted, no luck.

From the body size of the device I would think its about 3A something like a 1N5401 diode.

Whats the rating of the trunk bulb/lamp.?
a 3A diode would work OK upto 24Watts or so.

 

[snwsk8r8]

im not sure about the trunk bulb. i know it is a phillips bulb # 12818 and it is 12v. i doubt the bulb is more than 24watts becuase it is no more than an inch long.

 

[ericgibbs]

im not sure about the trunk bulb. i know it is a phillips bulb # 12818 and it is 12v. i doubt the bulb is more than 24watts becuase it is no more than an inch long.

I would get a 50V 3A diode, a 1N5401 is a common type and replace the suspect one, make sure you get the white bar on the new diode in the same position as the old one. The polarity is important.

 

[snwsk8r8]

the bar actually looks silver, if that makes a difference

 

[ericgibbs]

the bar actually looks silver, if that makes a difference

Just checked one of my 1N5401, its silver

Pity I cant pass it thru my screen to you.!

 

[snwsk8r8]

yeah i wish you could. so that diode is deffinately my problem?

 

[ericgibbs]

yeah i wish you could. so that diode is deffinately my problem?

Thats what our tests show, the next step is to get a new diode, I would think about $1 US.

Here's a pix.

 

[snwsk8r8]

awesome. ill have to try to get to radioshack today and buy it. i hope they have it. ill be sure to keep you updated. thanks for all the help so far!

 

[ericgibbs]

awesome. ill have to try to get to radioshack today and buy it. i hope they have it. ill be sure to keep you updated. thanks for all the help so far!

Look at the EDIT pix

 

[snwsk8r8]

yup that looks just like the one i have. i wish i could just pull it out of the screen. but that would just be too easy.

 

[JimB]

Eric

I disagree with your analysis that the diode is faulty.

The OP measured his diode using the "diode test" facility on his meter.
One way he measured 0.6v, the normal forward volt drop of a silicon diode, the other way he measured 1. the same as leads O/C.

In the 2k position on the meter, I dont think there will be enough voltage available to put the diode into conduction, so it shows O/C both ways.
(This is why meters have a diode test function).


I would conclude that the diode is OK.

JimB

 

[snwsk8r8]

Eric

I disagree with your analysis that the diode is faulty.

The OP measured his diode using the "diode test" facility on his meter.
One way he measured 0.6v, the normal forward volt drop of a silicon diode, the other way he measured 1. the same as leads O/C.

In the 2k position on the meter, I dont think there will be enough voltage available to put the diode into conduction, so it shows O/C both ways.
(This is why meters have a diode test function).


I would conclude that the diode is OK.

JimB

what would you think the problem is then?
also how come with my meter set at 200 it beeped with one lead anywhere along the red line except for after the diode (where the blue line is) and the other lead where the yellow is?
(see my first post withe image)

 

[ericgibbs]

Eric

I disagree with your analysis that the diode is faulty.

The OP measured his diode using the "diode test" facility on his meter.
One way he measured 0.6v, the normal forward volt drop of a silicon diode, the other way he measured 1. the same as leads O/C.

In the 2k position on the meter, I dont think there will be enough voltage available to put the diode into conduction, so it shows O/C both ways.
(This is why meters have a diode test function).


I would conclude that the diode is OK.

JimB

hi Jim,
My meters read/measure diodes OK , usually on the 2K range I get about 700R and infinite R in reverse.

My meters also also have a diode function.?