Auxiliary backup light wiring problem

[Erich_870]

I tried to install some back up lights today and found an interesting problem. First I have to say I read the FAQ thread about lighting and I used the KC link that Wabbit posted (TOF), so I'm stumped why this is occurring, but here's my problem.

When I test the lights by having the wife put it in reverse, I keep blowing the fuse in the cab for my gauges! The stock backup lights must be wired through them, so I have no gauge lights, or stock backup lights.

I can't figure out what's wrong! I took some pics of the wiring set up but I followed the schematic to the tee, as far as I can tell at least.

I have a fused power wire coming directly off the battery going to post 30 on the relay, then I have the wire leaving for the lights coming out of post 87. Post 85 has the wire tapped off the stock back up wire and 86 is the ground.

I ran several test. First, when hard wired (by-passing the relay) the lights work great.

When I disconnected the wire tape on the stock wire (and replaced blown fuse) the stock back up lights work.

I tested the relay's ground, it works.

I reconnected the relay and tested again and blew the fuse a second time.

Any idea where I went wrong?

Here's the pics

In the first pic you can see the red power wire on the bottom. I joined the two 18 gauge wires from each light into the 14 gauge wire (still need to fuse them of course) The tapped stock wire is the red on at the top
http://i7.photobucket.com/albums/y261/Erich_870/DSCN0009.jpg


This pic shows the relay and the 4 wires going to it. You can even see my labels on the wires! The black wire is the ground and it's connected to that yellow jumper wire so I could clip it to the rig. The pinkish wire on the right labeled "30" is the power cable coming in.
http://i7.photobucket.com/albums/y261/Erich_870/DSCN0010.jpg


This pic shows my wire tap to the stock wire. It is red w/ orange strip. This is not the color in the Chilton manual, but they don't even have a 4runner diagram so I did my own testing and it is the right wire. After I blew the first fuse I thought the tap was bad or cut the wire. I opened it up and it was fine. I got out my 12volt light and it was hot in reverse
http://i7.photobucket.com/albums/y261/Erich_870/DSCN0011.jpg

Hope someone has some suggestions :dunno:

Erich

[GSGALLANT]

How sure are you that you have the wires going to the right pins on the relay. You are checking the pin labels on the relay, and not just going from a picture in a writeup somewhere, right? There are different pin layout for relays, so double check it again.

The backup lights do draw power off the guage fuse, which is why you're losing your guage lights when you blow your backup lights fuse.

The wiring diagram for my 2002 4Runner shows the wires going to the backup lights being white with a blue stripe... I can't imagine it being different in a '99, but maybe.

Have you tested the relay outside the vehicle? It is possible that you have a bad relay with a short inside it. Measure the resistance between posts 85 and 86. I'm not sure exactly how high it should be, but definitely over 15-20 ohms (It may be as high as a couple of hundred ohms, depending on the relay...it doesn't matter how high it is, but if it's too low, you'll be drawing excessive current, which could be causing your blown fuses). If that tests out OK, connect post 85 directly to your battery positive terminal, and ground post 86. With the relay coil energized, check for continuity between posts 30 and 87.

[Erich_870]

How sure are you that you have the wires going to the right pins on the relay. You are checking the pin labels on the relay, and not just going from a picture in a writeup somewhere, right? There are different pin layout for relays, so double check it again.

I'm 99% positive I'm connecting the correct wire to the correct terminal, but I'll check again :)

The backup lights do draw power off the gauge fuse, which is why you're losing your gauge lights when you blow your backup lights fuse.

The wiring diagram for my 2002 4Runner shows the wires going to the backup lights being white with a blue stripe... I can't imagine it being different in a '99, but maybe.

That's one thing that had stumped me, but as you can see from the third pic, there are NO OTHER wires. I tested the Red w/ Blue stripe by disconnecting the plug for the driver side tail light and having my wife put it in reverse. Only the break light wire and the reverse wire was on. Then had her just push the break and verified that I had the right back up wire.

Have you tested the relay outside the vehicle? It is possible that you have a bad relay with a short inside it. Measure the resistance between posts 85 and 86. I'm not sure exactly how high it should be, but definitely over 15-20 ohms (It may be as high as a couple of hundred ohms, depending on the relay...it doesn't matter how high it is, but if it's too low, you'll be drawing excessive current, which could be causing your blown fuses). If that tests out OK, connect post 85 directly to your battery positive terminal, and ground post 86. With the relay coil energized, check for continuity between posts 30 and 87.

I have not independently tested the relay. I'll check it out today.



Thanks for the input, I appreciated it :thumbup:

Erich

[Erich_870]

Got the tester out at lunch and checked the relay. It appears it has a diode that forces me to reverse the 85 and 86 terminals. It had unlimited continuity going 85 to 86 but nothing going 86 to 85. I hooked it up "backwards" just to see and sure enough they worked perfect.

I'll snap a couple pics when I get a free second. Thanks for all the help.

I have some valuable info on the wiring colors and how to use a relay with a diode now.

Erich

[GSGALLANT]

Good stuff Erich. Glad you got it fixed.

[Robinhood4x4]

Wow, good job. My next suggestion was to tap in at the trailer light harness. That's what I did.

[Erich_870]

Thanks guys.

I finished wiring them up and put the cargo area panel back on. I'm still working on the rest of the wiring for the subwoofer.

Here's a pic where I put the relay. I wanted to be able to reach it without removing the panel so I put it behind the cover end cap. It fits perfectly between the little "feet"

http://i7.photobucket.com/albums/y261/Erich_870/S6301052.jpg

Here's a pic of them on. I turned the flash off, and the exhaust helped catch some more light. I noticed they put off some heat when I was positioning them :smokin:

http://i7.photobucket.com/albums/y261/Erich_870/S6301055.jpg

Erich

[Cebby]

That looks good! Glad you got it worked out.

[Euphorickaty80]

That is one bright rear end :spit: :rofl:

[Erich_870]

That is one bright rear end :spit: :rofl:


:lol: Thanks, hope no body says it a wide one too :flipoff:

I really wish I had these lights for last winter, but I wasn't about to try it with all the snow last year.

This winter is gunna be sweet! :clap:

Erich