87 Carrera horn fuse??

[Paul Crowther]

Yesterday I noticed my horn doesn't work and before pulling horn pad and likely breaking a clip button or two (I think I have spares) I figured I'd check the fuse. Bentleys and owners manual don't list the horn on their fuse lists. Tech reference same.

Anyone know which fuse? No other circuit is noticeably out. I was in hurry so didn't check them all closely.

Paul

[ossiblue]

From the diagrams on this site (latest is 82 SC), it looks to be fuse 17 (if someone else has a later version that shows another fuse, please chime in.)

Before you dig into the horn pad, check out the horn relay first, and check there for power from the fuse block. You can remove the horn relay and jump sockets 30 and 87, causing the horns to sound (be prepared for the noise.) If the horns work by jumping the sockets, the fuse is good.

You can use a test light to check the horn pad contact. Connect one lead of the light to a power source, and the other lead to socket 85 of the relay. Push the horn pad and see if the light comes on. If it does, the contact is good and you don't have to mess with the pad. If it doesn't (and you've double checked that you have power to one lead of the test light), the the problem is likely in the pad contact.

If both the above check out, the only remaining possibility is the relay itself. Does it click when power is applied to pin 86 and pin 85 is grounded? Is there continuity between pin 30 and 87 when power is applied to 86 and 85 is grounded?

[wayne robson]

Hi Paul,this may help, on my 84 its a relay no 3 thats third from
right, 87 may be different, just try another no 2 relay is fog lts on mine
that will fit as well--regards

[86 911 Targa]

^^^^^
Here you go.

Best,

Gerry

[Paul Crowther]

Ossiblue
Test 1: Jumping sockets 30 and 87 DID cause horn to sound, so that's fine
Test 2: Using a test light (voltmeter, actually) between positive battery terminal and socket 85...pushing horn pad the voltage did NOT register (same as test light not coming on, right?) However.....
Test 3: With the relay back in, pushing on horn pad I DID hear the relay clicking. Does that rule out horn pad contact? I didn't perform remaining test involving pins 86,85,30, and 87 b/c I didn't understand how to do it

[86 911 Targa]

^^^^^
Here's the CKT, but I'm not certain where the horn is fused.

Best,

Gerry

[86 911 Targa]

Originally Posted by Paul Crowther

Ossiblue
Test 1: Jumping sockets 30 and 87 DID cause horn to sound, so that's fine
Test 2: Using a test light (voltmeter, actually) between positive battery terminal and socket 85...pushing horn pad the voltage did NOT register (same as test light not coming on, right?) However.....
Test 3: With the relay back in, pushing on horn pad I DID hear the relay clicking. Does that rule out horn pad contact? I didn't perform remaining test involving pins 86,85,30, and 87 b/c I didn't understand how to do it

Have you swapped out the horn relay with any other relay on the fuse panel?

I suspect a corroded relay contact.

pm me as needed.

Gerry

[Paul Crowther]

Gerry,
About the time you posted your last comment about swapping relays, I'd started to suspect that was possible after reading more about the different relays. When I checked the fog light relay and saw the terminal numbers were the same, I felt comfortable swapping it. BINGO! Horn works fine.

Now I see Porsche relays and aftermarket available.....thoughts? Also, if I use fog relay for now in place of horn relay, are any other items disabled in addition to the fogs?

[86 911 Targa]

Originally Posted by Paul Crowther

Gerry,
About the time you posted your last comment about swapping relays, I'd started to suspect that was possible after reading more about the different relays. When I checked the fog light relay and saw the terminal numbers were the same, I felt comfortable swapping it. BINGO! Horn works fine.

Now I see Porsche relays and aftermarket available.....thoughts? Also, if I use fog relay for now in place of horn relay, are any other items disabled in addition to the fogs?

The fog light relay is exclusively for the fog lights.

Do you have cruise control?

If not use that one.

I don't like to buy "used" for electrical equipment.

Your call.

Best,

Gerry

[Paul Crowther]

I was mixed up. I didn't use the fog relay. #1 in your diagram is for footwell blowers but in my Bentleys it's labeled "not used". That's the one I swapped for the test.
My #2 is "power windows". I don't have cruise and there's no relay in that #3 position.

[86 911 Targa]

The pic I posted is from the Bentley for your M/Y 1987.

Something is not right with your relay designation(s),
which appear to be for the M/Y 1984-1986.

My posts were predicated on M/Y 1987 ownership.

Gerry

[Paul Crowther]

Yup. Wrong relay images. Looking at 84-86 in Bentley. Following page is for 87-89. I think I'll do something else for a while. And shop for a new horn relay.

Thanks for your help, all of you. Another page in the book of lessons.That's how we do it.