Afternoon all. Been working on my van for a bit. Got it over a year ago and have been learning as I go to fix things. This site has been a blessing when I recently had a crank with no start issue. Looked all over, changed a few parts that needed to be changed, fuel filter, plugs and few others. Found out that my IAC valve was gunked up and needed to be replaced. I still l have not replaced it, but it has been cleaned. One of the old problems is the driver door power window and mirror switch was melted. An obvious short somewhere, not sure where. Replace the factory mirrors with some new ones because one of them was broke, but the fuse will blow after a few minutes. I metered out the switch and it has power at all times to the plug. Is this correct? If it is not supposed to have power at all times to the mirror side of the switch, then I need to look at wiring between both mirrors to see if I have an issue in what I can see. I need to get another handful of fuses and try this with one mirror at a time and see if I can isolate it to one side and cut half the workload.

Has anyone had this issue before. 1992 E150 5.0 that had a conversion package installed.

 

IN ADDITION TO,buying more fuses,, consider investing in a test light. There are all kinds, good ones and cheap ones.A good one will come with a heavy duty clamp and heaver wire while a cheapy comes with a crummy clamp that may work one time and maybe with a foot and a half of wire . That piece of junk is good only for connecting across battery terminals and is next to useless.As for why you might consider purchasing one,


Well, if you connected the test light in place of the fuse and if there is a short the test lite will lite up.. So , all you need to do now is find by careful inspection, and maybe in the door hinge area or any area where the wires come in contact with sharp edges. When the light goes out, you found the short to ground.

Now you have just become an experienced automotive electrician. I have every confidence in you ! What do you think?

 

Thanks Hanky. This thing sat around for awhile and we found more than one mouse nest and poop, so other than age it could be I have some chewed on wires. I will need to update my short probe since I can't find my old one, but I can always use new tools. After first finding the switch roasted we replaced it and t tried it. With a new fuse and new switch and mirrors it took a couple hours for the fuse to blow again. I expected a fast blow but it sat without anyone around and it went. I will try to shoot it down to one mirror or the other hopefully this way. The manual mirrors are ok, but the power mirrors would be better since other people drive it.

I will get to this over the weekend and get back to this. Have a good day all.

 

Without a worthwhile diagram, you might consider removing the drivers side interior door panel and see which wires go to the mirrors. At least you would have some idea o what colors to follow. And sometimes they change colors at plug connections.

If the fuse is managing to blow with no movement selected it should be pretty easy to just follow the wire that brings power to the switch..
It must be contacting a ground between the fuse panel and the control switch. What do you think?

 

i found a wiring diagram, mostly. The power wire to the mirror switch is a light green/yellow it runs to all the door switches for the courtesy lights, radio power and a bunch of stuff. I do have the door light switches unplugged after finding one jammed in i did pull the fuse from the panel, #8, and found some random voltage in the power wire if there is a ground, or open along this somewhere then short of pulling fuses till I find the one responsible, not sure what more i can do with the current setup My thoughts are i have 3 options, 1) I chase down the current wire paths and fix the short or open. 2) i put in a separate power switch to turn power on to the mirror switch only when needed and last 3) tap into a keyed power wire to the window switch so i have power to my mirror switch when the key is on and not hot at all times. i did shoot back through the wires on the connectors to the mirrors, 3 each, and found no grounding out. I will check back in and let you all know how it works out Appreciate the help Hanky. Times like this I miss not having my father around who was a mechanic his whole life. Best lesson I learned from him was " cant help if you don't ask."

Good weekend all.

 

I am going by what you describe, and that is power comes to the mirrors through that LT GRN wire. If there is a possible intermittent short to ground in that wire OR anywhere else that wire goes to supply power it will cause the fuse to blow.

That brings up another question, which is the mirrors may not have anything to do with causing that fuse to blow.
Best place to start looking is right at the fuse panel underneath..

 

Good point about the fuse panel. It is a mess under there. This is a conversion van so stuff has been added and the previous owner was kind of ham fisted when making additions to the electrics. I have not blown a fuse since unplugging the new mirror switch was installed. The other switch was melted down and one of the mirrors was broken We replaced the mirrors and started to pop fuses after plugging it in. My guess too would be the power wire, light green/yellow, may have a short between the connector and the fuse box. I will try to find the wire path from the connector to the panel. Gonna plug it up and see how long it takes to pop the fuse. I will get back to you later.

 

You state the switch was melted.
And if the switch was disconnected , no blown fuse, correct?
Evidently , the switch is defective because of excessive load/heat which was most likely caused by the defective mirror assy.

One way you can verify the circuit is to measure the current drain (amps) with the switch removed and mirror disconnected. Record that reading.
It should be well below the fuse rating that is blowing. If it is not , let us know.
Once you know the circuit is good you can connect the switch and new mirror assy and see how much current that draws.It should be below the fuse rating if all is good.

Now someone might have another suggestion that might be easier for you to use, but that is the way I would handle it.

 

Hanky i appreciate your going through this with me. Started some more troubleshooting this morning. Hooked up switch to mirrors and let it sit with no mirror selected. The fuse is hot at all times so there is power to the switch at all times, just have to select left or right to move that mirror. Cycled the mirrors around a few times and then it started to move on its own. I could go back to center on the switch to stop it, but it may or may not power off if i select a mirror again. I have a new switch and new mirrors but the harness to the switch is old and has a burn mark from the old switch. Luckily it is a basic wire bunch at the switch. There are two wires to the left and 2 to the right with a common yellow to both. I have a yellow/green for power and a black for ground. Thoughts are what happened to the previous switch was it got stuck powered on and kept driving a mirror till it overheated and burnt up. Everything ohms out fine but i obviously have something that is putting power to the switch when it shouldn't. I will keep at it and will check in when i figure it out Thanks for all of the ideas and areas to look at Hanky.

 

If what you suspect regarding something putting power to the switch movement contacts when not requested there may be a module involved that is malfunctioning, maybe "Front electronic Module".