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, 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?

Thanks,

Erich

Erich_870

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



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.



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


Hope someone has some suggestions

Erich

Erich_870

Morning

Erich

Albuquerque Jim

Try this:

85 Ground
86 Tapped to Reverse
87 to Lights
30 to Battery

You are just switching the ground and the switched input.

Make sure you have the lights grounded as well.

GSGALLANT

Polarity only matters if it's a diode protected relay, but that may explain the problem. If it is a diode relay, then it should be identified on the relay case.

If it is a diode relay and you have the coil leads swapped, then when you select the shifter to "reverse", which supplies 12V to your reverse lights wire, then that voltage has a direct path to ground through the diode (which lets current through one way only, and is wired in parallel to the relay's coil). This path will have very little resistance, so the current will be high enough to blow your fuse.

If the diode relay is connected properly, then the only path for electricity to flow to ground is through the coil, which has a high resistance, so the current through it is low. Take a look on the relay to see if it's identified as a diode protected relay.

Erich_870

Thanks guys ,

I check out the relay for a diode. Napa charged me $15 for it, so it better not be defective!

Erich

Erich_870

Here's a couple pics of the relay. It looks like it does have a diode, if my memory of my fundamental circuits class still works



Here's the numbering for the posts



Guess I try reversing the posts from the tapped brake line and the ground and see if that works. I picked up a bunch of extra 10A fuses so I have some to experiment with

Erich

Erich_870

It's alive!!

I slipped out of the office for a second and tested the relay. It's definitely the diode that's causing the problem. Terminal 85 to 86 I have unlimited continuity. Terminal 86 to 85 I have nothing.

I hooked it up "backwards" for giggles and sure enough it worked.

I'll snap some pics when I get another chance. I have to finish routing the wires this evening so I can put all the panels back on

Thanks for all your help!

Now I some info for people trying to wire their 99' 4runner.

Erich

Erich_870

Thanks everyone who posted,

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"



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



Erich

Elton

good to hear u got them working napa sucks for relays they want like $10 dollars for them i get all mine at carquest for $4 dollars

Erich_870

No kidding, I paid $15 for mine. I needed a new air filter and it's close to my house, so I decided not to make a second trip to Radio Shack (read: no value parts stores in town)

I was going to go back and hit them with the relay, had it not worked out

Erich