Need help rewiring my new horn relay connector.

[ulrichd]

The PO for my 70T had jury rigged the horn with an off the shelf domestic 3-pin relay. Just got my new horn relay and pin connector, but the wire colors don't match up (see pic) with the wire colors in my car.

Looking at the wiring diagram the car has the correct wire colors (Red to #2 fuse, Brown to steering wheel, black/yellow to horns), but the socket has 5 wires and I have no way of matching up the numbers on the relay to the wires.



Can someone help?

Ulrich

[ulrichd]

Just addtl. info:
- Pin 87: Black/yellow wires from horns
- Pin 85: Brown/white wire from steering wheel
- Pin 30: Red wire to fuse #2
- Pin 87a: empty
- Pins 30/86: jumped

Since I can't open the pin connector I can't match the numbers up with the wires.

Ulrich

[boyt911sc]

Ulrich,

First of all, check if the horn relay and the relay socket match or compatible for your need. Do this investigation:
Test 1: Determine the terminals in the socket that are bridged or jumpered. There should be only two (2) bridged terminals. If yes, continue.....

Test 2: Check if these two (2) bridged terminals coincide with pin #30 and #86 (relay socket). If, yes, continue.......

Test 3: Plug the horn relay to the socket. There will be four (4) terminals/wires that will be bridged at this point. The single terminal that is not connected to these four is terminal #87.

Test 4: Check if this isolated terminal coincide with pin#87 (relay). If yes, then the rest of the terminals could be easily identified accordingly. Keep us posted.

Tony

[ulrichd]

Tony,
Sorry for being dense, but how do I determine TEST 1. I can't open the socket, or at least I don't think so, in order to follow the wires. The new horn relay I purchased is correctly numbered as per the wiring diagram

Ulrich

[HarryD]

Looking at this wiring Diagram (http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_1971_Part-2.jpg)

They show relay #49 wired as follows:

Terminal 30 - to Fuse panel and terminal 86 (Red Wire) - This is the power to the relay coil and the horns.

Terminal 85 - Horn Button (brown/white wire) - this ground the coil via the horn button.

Terminal 86 - Jumpered to terminal 30 (red wire) - this provides hte power from the battery to the horns themselves.

Terminal 87 - To Horns (Yellow/Black wire) - This provides power to the horns when the coil is energized.

Terminal 87a - Not used

[ulrichd]

Right Harry, that's the info I have as well. And I have a new horn relay that is numbered correctly as per the diagram.

The problem is the new horn socket I have, which fits the relay, has wires of a different color and I have no way of matching the wires with the pin position as the socket is sealed.

Electrical/wiring work is not my strong suit.

Ulrich

[ulrichd]

Here is the socket and relay. Based on the numbered marking on the relay I can identify the pins as shown on the pic, but since the wires come out the bottom I don't know which wires go to which pin.



Ulrich

[spuggy]

Heh. I hate when a seemingly simple task gets more complicated than you thought it would.

Odd how the socket doesn't have the right colors though.

I'm guessing you don't have a multimeter? Even a very cheap one is very usable/useful for most car wiring projects. Quality improves quite dramatically with each additional $10 spent in this price range... I find the $40 ones only seem to last about 5-8 years, so I bought a used Fluke last time around. That'll probably last forever.

Failing that, a battery, some wire, a prod and a bulb/LED/buzzer?

[HarryD]

Ulrich,

If you do not have a multimeter at this time, this is a good excuse to get one. Even a $5.00 one from Harbor Freight will do the job. I still use the cheap one from Radio Shack I bought in 1970.

Using your picture, set the meter to ohms (touch the two meter leads together to verify zero ohms and adjust meter as needed). Touch a pin in the socket with one lead. Use the other lead on the meter to touch each wire until you find the one with zero resisitance. This is hte wire for that hole. Label it. Lather, rinse, repeat until you get them all identified.

[ulrichd]

Spuggy I have looked at multi-meters, checked some youtube videos on how to use them but you still may as well ask me to land the space shuttle.

I can adjust springplate/ride height, change rotors, brakes and bearings all day long but don't ask me about wiring. What the heck is a prod?

Can you please explain how I might test the individual pins with wire, a bulb, and the car battery without shorting my electrical system?

Thank you.

Ulrich

[boyt911sc]

Originally Posted by HarryD

Looking at this wiring Diagram (http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_1971_Part-2.jpg)

They show relay #49 wired as follows:

Terminal 30 - to Fuse panel and terminal 86 (Red Wire) - This is the power to the relay coil and the horns.

Terminal 85 - Horn Button (brown/white wire) - this ground the coil via the horn button.

Terminal 86 - Jumpered to terminal 30 (red wire) - this provides hte power from the battery to the horns themselves.

Terminal 87 - To Horns (Yellow/Black wire) - This provides power to the horns when the coil is energized.

Terminal 87a - Not used

Ulrich,

All the above statements are correct. To do the tests that I mentioned previously, you need a continuity tester (Multi-tester) or a simple test-light in conjuction with a 12-volt source to trace the wire's continuity.

The picture you attached shows only 4 wires but you said 5. For your horn relay socket, you need only 3 wires coming out from the socket to complete the wiring set-up. Namely, #30 (#86 is bridged with #30), #87 (power to horns), and #85 (ground wire for he coil) going to the steering column.

You can test the individual wire for continuity. So each wire from the socket will correspond to a particular terminal (pin connector) except #30 & #86 (jumpered). After you identified the wires for terminals #30, #85, & #87, follow the wiring diagram and connect. Do you follow?????

Keep us posted.

Tony

[ulrichd]

Originally Posted by HarryD

Ulrich,

If you do not have a multimeter at this time, this is a good excuse to get one. Even a $5.00 one from Harbor Freight will do the job. I still use the cheap one from Radio Shack I bought in 1970.

Using your picture, set the meter to ohms (touch the two meter leads together to verify zero ohms and adjust meter as needed). Touch a pin in the socket with one lead. Use the other lead on the meter to touch each wire until you find the one with zero resisitance. This is hte wire for that hole. Label it. Lather, rinse, repeat until you get them all identified.

Hmm, now this I might be able to do without blowing anything up. Off to Pep Boys I go for a multi-meter.

Ulrich

[boyt911sc]

Ulrich,

Using a multimeter set @ CHECK for continuity.


Socket is hooked up for testing. A beeping sound comes on when you get continuity.


Simple 12-volt test light:


See the bulb GLOWING???? This shows continuity low tech version.


Hope this helps. This is from Electrical Lab Course 101.

Tony

[ulrichd]

Ok,
Thank you all for sticking with me on this. Thanks to Harry I was able to correctly identify the pins and wire the relay socket with my new super duper multi-meter. As soon as I reattached the battery ground wire the horn sounded and unfortunately continued sounding.

Looking at Tony's pic I don't have the right socket. Mine does have 5 wires, his has only 3. I will get with DCauto or some of the other used parts suppliers to see if I can get the correct 3-wire socket.

Thanks everyone for your help on this.

Ulrich

[boyt911sc]

Ulrich,

Check the relay socket if #30 and #86 are bridged (jumpered). If this is the case, this socket is usable. Use #85 and #87. And you'll be OK. The key is determining which terminals are bridged. Relay sockets are different for fuel pump and horns.

Tony

[HarryD]

Ulrich,

Have you verified that, for the socket, #30 and #86 are connected? You can do this by using your multimeter in ohms mode and verify that when you connect to end of wire #30 and wire #86, you have continuity.

Also, when you press the horn button, does the horn STOP blowing. If so, then you have the horn on #87a not #87.

Also, check that your relay is not shorted. With the relay unplugged, check the pins. You should have continuity from #30 to #85; Contiunity for #86 to #87a; and NO continuity for #86 to #87.

[ulrichd]

Harry,
Using the multimeter 30 and 86 are not connected.
Checking the relay I got cont. from 30 -87a and 85-86.

So I have the wrong socket and relay????
Ulrich

[ulrichd]

This is the relay I order. Based on the description it's the correct one.

http://www.pelicanparts.com/cgi-bin/ksearch/pel_search.cgi?please_wait=N&forumid=8&threadid=&command=DWsearch&description=91161510901&x=14&y=10&FILTER_911E=ON&FILTER_911M=ON&FILTER_911L=ON&FILTER_TECH=ON&FILTER_SUPP=ON&FILTER_ACCE=ON&FILTER_CARE=ON&FILTER_STUF=ON&FILTER_PERF=ON&FILTER_MISC=ON&FILTER_GADG=ON&FILTER_TOOL=ON

[HarryD]

Originally Posted by ulrichd

Harry,
Using the multimeter 30 and 86 are not connected.
Checking the relay I got cont. from 30 -87a and 85-86.

So I have the wrong socket and relay????
Ulrich

Hmmm.

So 30 is NOT connected to 86 in the Socket? It should not be connected in the relay.

On the relay, 30 to 87a is ok.

So is continuity of 85 to 86.

OK, lets move forward.

You will need to fabricate an external jumper for the relay socket to connect 30 to 86.

Then, try this:

Assuming the relay socket is still wired in and with the relay unplugged.

Right now, you should have 12 volts between socket pin 30 and ground and no where else (if you have 12 volts at pin 86 all the better but I do not think so until you make the external jumper). Please verify and correct as needed.

Use a jumper (a paper clip will do) to connect pins 30 to 87 in the socket. Your horn should sound. If not, verify that you did not accidentally connect the horn to 87a. Correct if needed. This will verify that your horn power circuit is correct.

Now connect your continuity tester to pin 85 and the other lead to ground. You should have no continuity. Press the horn button and you should now have continuity. This verifies that your horn button is grounding correctly. Correct as needed.

Plug in relay and honk happily....

[Rich Lambert]

30 years ago, when I lived on Woodway Drive, just off the 610 Loop, I would have gone over to your house and we would've had this done in about 10 minutes.

Okay, here's what you're looking at, horn relay-wise...forgive my crude drawing.


Simply put, to fire a relay you need positive and negative power applied to the relay coil, in this case - positive at term 86 and negative at term 85. The squiggly line is the coil.

The positive comes from the #2 fuse to term 30 to term 86. 30 to 86 is a jumper wire which may be inside the plug or the relay. That half of the circuit is alway hot.

The negative comes from chassis ground to the horn button switch to term 85. The circuit is completed when the horn button is pushed - that causes the relay to fire.

Inside the relay are 3 more terminals; 30-which is common, 87A-which is normally open, and 87-which is normally closed. "Open" is open circuit. "Closed" is closed circuit. There's a wiper connected to 30 which goes to 87A when the relay is in the relaxed position and to 87 when the relay is energized. When the relay is energized (+) power goes from 30 to 87 to the horns. The horns also have ground wires (-).

Set your multimeter to DCV, probably the 200 range.
- With the black probe touching ground, touch the red probe to 30 & 86. You should read 12VDC at both terms of the plug.
- With the red probe on the (+) side of the battery, touch the black probe to 85. You should read 0VDC. Do that again with the horn button pushed. You should read 12VDC.

If the horn is always on, you could have a bad rubber collar on the steering wheel, a bad horn switch on the steering column, or the wires could be crossed between 87 & 87A.

Good luck...