308 Electrical problem

30 - Battery voltage
87 - to the lights
86 - 12v from your fuse
85 - ground

Is this how you have it Chip?

 

30 and 87 are the main contacts, they work as a pair.
85 and 86 are the actuating coil, they work as another pair.

You can reverse 85 and 86 on most relays and it'll work.
You can reverse 30 and 87 and it'll work.

But don't mix across pairs.

The connections listed above will produce the results you want.

But you ought to have an inline fuse on the line from the battery to pin 30.

The parking light fuse will protect the "secondary" (coil) circuit, but you should have a separate fuse to prevent excess current on the primary (fog lights) circuit.

 

Each of your posts has the answer but you ignore it. You have no voltage from the battery getting to the relay.

 

What switch?

You're driving your relay off the parking light fuse. The car switch is well back from there (operating the parking light relay).

Image Unavailable, Please Login

Your test light (with one end grounded) should light up on pins 30 and 86 (when your parking lights are on).

When you turn on your parking lights, you should hear (or at least feel) the relay operate.

A relay circuit can be diagnosed in two parts. First get the coil circuit operating. When the parking lights come on, the relay should "click".

When you have that part working, you can trace the circuit on the contacts -- fused battery voltage to pin 30, and connectivity from 87 to the fog lights.

(Oh -- silly question: you did ground the other connection on the fog lights, didn't you?)

 

Please DO NOT use the phrase "complete circuit" as it has ambiguous meaning, and has no place in an electrical discussion.

You say your tester shows +12v only on the relay wire which came from the parking light fuse. The tester SHOULD ALSO indicate +12v on the relay wire which came from the battery (relay #30) and on the relay contact (#37) but you didn't say that, something is probably wrong with that wire/fuse/connector from the batter to relay #30.

You also said (in a convoluted way), connecting the battery to the fog lights turns them on but connecting the battery wire to the relay doesn't turn the fog lights on. It therefore sounds like there is a bad connection at the relay wire coming from the battery.

Your tester is your friend, believe what it indicates. Print out DGS's great schematic and using the tester, look for +12v on the wires he indicates by number around the relay socket except the ground. Your tester must indicate +12v on #30, #86, and #87 and (important) zero volts at ground #85. If it does, use the tester to find voltage at the fog light sockets. Only then should the fog lights come on. Use the tester and find either +12v or 0V and report the exact location of those voltages if you still haven't found the bad connection.

 

Well there's one possible issue: You wired to the low beam fuses, not the parking light fuses.

Do your fogs work when your low beams are on?

 

It's telling you that tester is intended to be grounded on one side, it's measuring the DIFFERENCE in potential...

Connecting it to two points hot at 12V will show nothing at all (in DIFFERENCE of potential) but both points would show "12V' if either was measured to ground.

I'm not good at electrical explanations......

 

One step at a time --- Does the new relay click when you turn the parking lights on?
If that works, then your relay coil circuit is okay, and you can focus on the relay contacts circuit.
If not, you have to get that part working first.

On the contacts circuit, if you're showing "continuity" but no voltage at both sides of the relay contacts (pins 30 and 87), then it sounds like the relay is operating, and you have continuity to ground through your fog lights, but no voltage from the battery.

 

Did you, by any chance, mix up the "+" and "-" terminals at the battery?
That clamp where you connected the wires looks like it might be ground.
Check the labels on the battery.

(If you have your "+" wire hooked to battery "-", then you have "continuity" to ground, but running the tester "ground" to the other battery post will give you -12v across the tester ... backwards.

 

No, when you JUMP the battery backwards, catch your Toyota on fire and have to rebuild the Ferrari alternator.........

Glad you got it sorted.....

If you are tapping the battery directly be sure to fuse it, in each wire.....close to the terminal.

 

Toss that test light, it's crap and is misleading you. Or tape over the 6v and continuity lights, or better yet make a great test light from a small car light bulb and two pieces of wire. Clip one wire to the car body ground. Touch a electrical contact with the other test light wire. If the bulb lights you have voltage. If it doesn't you don't have voltage. Had you done this many moons ago you would have had no problems as you would learned immediately that you had no voltage at the +wire (You stated this very fact several times yet chose to ignore it). A simple test light can be your friend. Listen to your friend.

[edit] It just struck me your strange use of the phrase 'completed circuit' probably comes from the 'continuity' on your test light becoming lit. NO, continuity doesn't mean completed circuit. Just toss that test light, please and save everyone's time.

 

Chip, just remember -- experience is what we learn from our mistakes. Wisdom is what we learn from other people's mistakes. So, now that you are experienced, you'll never make that mistake again. And hopefully anyone who reads this thread has gained the wisdom not to make it either.

Now, one other tip here -- that red cover on the other terminal on the battery.... it is usually a dead giveaway that THAT is the + terminal. Always best to check the markings on the battery itself for + and -, but if one terminal has the red cover and the other has no cover at all, it's a pretty good bet that the one with the red cover is +.

Let us know how the project works after you make the switch to the other terminal. And post a pic of the car with the fog lights so we can see how it came out.

p.s. It is always a good idea to have that cover over the + terminal on the battery to prevent an accidental short that could really ruin your day.