| Author |
Message |
shakers73
Samba Member
Joined: June 14, 2011
Posts: 820
Location: Saltville, Va
|
 Posted: Wed Aug 05, 2020 6:10 am Post subject: Switched Fuses |
 |
|
I have an empty slot in my fuse box. #7 is for accessories and has no wires connected at either side. I want to add a stereo and and an electric windshield washer pump to it. My question is Which side is made hot by the fuse? Upper or lower? And which fuse can I piggy back that is made hot by the ignition switch?
_________________
shakers73
'74 Super Beetle
'67 Beetle
Where there is no vision, the people perish. |
|
| Back to top |
|
 |
runamoc 
Samba Member
Joined: June 19, 2006
Posts: 5606
Location: 37.5N 77.1W
|
| Posted: Wed Aug 05, 2020 6:18 am Post subject: Re: Switched Fuses |
|
|
'Usually' power is applied to the top terminals. Top as in your photo. The black wire all the way to the left is probably wire #15 (key switch on hot) Check with a VOM to be sure
_________________
Daily driver: '69 Baja owned 44 yrs - Plan B: '81 Rabbit Diesel LS Deluxe - Plan C: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs-
VW Wiring = It's just wires |
|
| Back to top |
|
|
Luft kühl
Samba Member
Joined: January 21, 2009
Posts: 1178
Location: Allentown, PA
|
| Posted: Wed Aug 05, 2020 11:12 am Post subject: Re: Switched Fuses |
|
|
| shakers73 wrote: |
| I have an empty slot in my fuse box. #7 is for accessories and has no wires connected at either side. I want to add a stereo and and an electric windshield washer pump to it. My question is Which side is made hot by the fuse? Upper or lower? And which fuse can I piggy back that is made hot by the ignition switch? |
You can not just piggy back the supply for the new fuse from a "switched hot" fuse. All of the additional current load will still be drawn through the (#15 circuit) contacts of the ignition switch, causing it to fry.
The correct way to do it would be to get an inexpensive generic 30A relay at the auto parts store, and tap the #15 circuit to energize the relay.
What size fuse are you going to need for fuse #7 ? This will determine where the relay needs to be powered from. |
|
| Back to top |
|
|
shakers73
Samba Member
Joined: June 14, 2011
Posts: 820
Location: Saltville, Va
|
| Posted: Wed Aug 05, 2020 5:54 pm Post subject: Re: Switched Fuses |
|
|
| Luft kühl wrote: |
| shakers73 wrote: |
| I have an empty slot in my fuse box. #7 is for accessories and has no wires connected at either side. I want to add a stereo and and an electric windshield washer pump to it. My question is Which side is made hot by the fuse? Upper or lower? And which fuse can I piggy back that is made hot by the ignition switch? |
You can not just piggy back the supply for the new fuse from a "switched hot" fuse. All of the additional current load will still be drawn through the (#15 circuit) contacts of the ignition switch, causing it to fry.
The correct way to do it would be to get an inexpensive generic 30A relay at the auto parts store, and tap the #15 circuit to energize the relay.
What size fuse are you going to need for fuse #7 ? This will determine where the relay needs to be powered from. |
The stereo draws a maximum 15 amps. Not sure about the washer pump. Any suggestions.
_________________
shakers73
'74 Super Beetle
'67 Beetle
Where there is no vision, the people perish. |
|
| Back to top |
|
|
Cusser
Samba Member
Joined: October 02, 2006
Posts: 31396
Location: Hot Arizona
|
| Posted: Wed Aug 05, 2020 7:17 pm Post subject: Re: Switched Fuses |
|
|
| shakers73 wrote: |
| The stereo draws a maximum 15 amps. Not sure about the washer pump. Any suggestions. |
15 amps is a LOT for a stereo, typically 3 amps or so. I'd re-check that. They usually have an inline fuse of that size.
Electric washer pump would be small draw, I have them on both my VWs, just off an 8-amp fuse on the fuse box.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
|
| Back to top |
|
|
shakers73
Samba Member
Joined: June 14, 2011
Posts: 820
Location: Saltville, Va
|
| Posted: Wed Aug 05, 2020 9:31 pm Post subject: Re: Switched Fuses |
|
|
Here are the specs on the stereo:
_________________
shakers73
'74 Super Beetle
'67 Beetle
Where there is no vision, the people perish. |
|
| Back to top |
|
|
meranda
Samba Member
Joined: August 09, 2015
Posts: 280
Location: Melbourne Australia
|
| Posted: Thu Aug 06, 2020 4:15 am Post subject: Re: Switched Fuses |
|
|
There is no way this radio could consume 15 Amps equal to 180 watts . Maybe a decimal place is missing and 1.5 Amps is correct.
_________________
Currently filling the garage
1961 beetle cabrio
1971 Superbug
1974 Porsche 911S Targa
1968 1500 Beetle A Project!
Past Garage fillers dozens of type1 &type3 VWs
Jaguar Mk5 & XK120
Lancia Flavia Coupe
Alfa Guilia sedan |
|
| Back to top |
|
|
andk5591
Samba Member
Joined: August 29, 2005
Posts: 16757
Location: State College, PA
|
| Posted: Thu Aug 06, 2020 5:05 am Post subject: Re: Switched Fuses |
|
|
Pretty sure I just use an 8A fuse for Retrosounds. Unless you were adding power amps, you will be fine jumping from the switched hot to that fuse holder. Your washer pump draws very little. Keep in mind you also need a constant power for memory and just coming splitting off any of the low power non-switched if fine for that.
_________________
D-Dubya Manx clone - 63 Short pan,1914.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Cindy's daily driver.
Max - 73 standard Beetle hearse project - For sale
66 bug project - Real patina & Suby conversion
There's more, but not keeping them... |
|
| Back to top |
|
|
runamoc
Samba Member
Joined: June 19, 2006
Posts: 5606
Location: 37.5N 77.1W
|
| Posted: Thu Aug 06, 2020 5:30 am Post subject: Re: Switched Fuses |
|
|
possible the specs call for a 15 amp fuse for the feed but the current consumption, what current it's actually using, is .0035 amps
_________________
Daily driver: '69 Baja owned 44 yrs - Plan B: '81 Rabbit Diesel LS Deluxe - Plan C: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs-
VW Wiring = It's just wires |
|
| Back to top |
|
|
tzepesh
Samba Member
Joined: May 28, 2003
Posts: 735
Location: Romania
|
| Posted: Thu Aug 06, 2020 7:00 am Post subject: Re: Switched Fuses |
|
|
Runamoc, the unfused power is the row next to the relays connections. The top row is the "exit", the fused wires.
AFAIK, the radio needs two power connections: a fused direct battery connection (KL30) and a fused switched voltage connection (KL15). KL15 is just a wake/sleep signal, it does not draw a lot of power. But on KL30 it could draw more, for example ~4Amps if you listen to about 50W of RMS power (that's a LOT!!!). I think you can re-use Fuse 7 which is normally un-assigned for one of them. But you still need to add an in-line fuse for the other one...
_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration |
|
| Back to top |
|
|
ashman40
Samba Member
Joined: February 16, 2007
Posts: 15989
Location: North Florida, USA
|
| Posted: Thu Aug 06, 2020 10:46 am Post subject: Re: Switched Fuses |
|
|
| tzepesh wrote: |
| ... the unfused power is the row next to the relays connections. The top row is the "exit", the fused wires. |
This is correct.
From your pic:
You can see the INPUT side of the fuse as the connections where two fuses are connected together with a shared brass bar. If you look closely you will see that there are no bridged fuses along one edge (OUTPUT side) while nearly every fuse on the other edge are paired together. The bridged side is the INPUT side.
This bridge allows one source wire to power two fuses. The best example of this is the single yellow wire from the headlight dimmer relay which runs to fuse #4 (fourth from the right in your pic) but the bridge allows it to power both #3 and #4 fuses (left & right headlights).
Any wires connected to the INPUT side are NOT protected by the fuse. The wires on the OUTPUT side of the fuse are protected. When the fuse blows power to the OUTPUT side is interrupted. Because of this, be sure to disconnect the battery before doing any work on your fuse box.
You have three choices for connecting a power source to fuse #7:
1) Run a jumper wire from the #11 or #12 fuse INPUT to the #7 INPUT. This draws power from the #15 ignition switched circuit. As mentioned above, pulling an additional 15A over the #15 circuit would not be desirable. But the #15 circuit should be able to handle an additional 5A without a big problem.
2) Run a jumper wire from the #10 fuse INPUT to the #7 INPUT. This draws power from the #X ignition switched circuit. This circuit is similar the #15 circuit but is NOT powered while the engine is cranking. If you are okay with the stereo loosing power while cranking the engine this is a better source than #15. The #X circuit has a different path from the #15 and does not add more load to the #15 ignition circuit. #X was designed for non-critical devices.
3) As suggested above, add a SPST (or SPDT) relay. The relay draws power from the INPUT side of the #8 or #9 fuse (#30 constant battery source) but is controlled by the #15 or #X circuits. Run a jumper wire from the relay OUTPUT to the #7 INPUT. By using fuse #8/#9 this arrangement draws power from the battery without adding a load to any switches. The load to energize the SPST relay is only around 0.05~0.10A. This is a very small load.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road  }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
|
| Back to top |
|
|
shakers73
Samba Member
Joined: June 14, 2011
Posts: 820
Location: Saltville, Va
|
| Posted: Thu Aug 06, 2020 2:02 pm Post subject: Re: Switched Fuses |
|
|
Thanks, Ashman40. So I can piggy back the #8 input side with a wire to terminal 30 on the relay. Connect another wire from terminal 87 to input side of fuse #7. Then a wire from terminal 85 to ground. Assuming all this is right, what would be a good source to run to terminal 86? Do I need to use 87a?
_________________
shakers73
'74 Super Beetle
'67 Beetle
Where there is no vision, the people perish. |
|
| Back to top |
|
|
jlex
Samba Member
Joined: January 23, 2009
Posts: 2902
Location: NW Pennsylvania
|
| Posted: Thu Aug 06, 2020 6:11 pm Post subject: Re: Switched Fuses |
|
|
If you're switching to a washer pump, do like I did and install a variable speed/ intermittent wiper switch at the same time. Is a terrific upgrade. Mine has the washer button in the center of the switch.
Had to change positions with the light switch due to clearance, but was well worth the effort.
Couldn't handle the constant leaks from the pneumatic washer system anymore. Gave it plenty of time with new switch, hoses, etc. but in the end I gave up. One fried radio due to leaking was enough for me...
_________________
jlex.
'70 std. "Elsie"
'88 Carrera |
|
| Back to top |
|
|
jlex
Samba Member
Joined: January 23, 2009
Posts: 2902
Location: NW Pennsylvania
|
|
| Back to top |
|
|
ashman40
Samba Member
Joined: February 16, 2007
Posts: 15989
Location: North Florida, USA
|
| Posted: Thu Aug 06, 2020 7:24 pm Post subject: Re: Switched Fuses |
|
|
| shakers73 wrote: |
| Thanks, Ashman40. So I can piggy back the #8 input side with a wire to terminal 30 on the relay. Connect another wire from terminal 87 to input side of fuse #7. Then a wire from terminal 85 to ground. Assuming all this is right, what would be a good source to run to terminal 86? Do I need to use 87a? |
That sounds correct.
Connect 86 to either fuse #11 or #12 OUTPUT. This will add a small 0.050A of extra load to the fuse. It should not be a problem for that circuit.
The 87a terminal is only found on the SPDT relay and is the NC (normally closed) circuit connecting to 30 when the relay is OFF. It is not used in this arrangement.
If you really want to be safe, apply some shrink wrap/tubing around the 87a terminal if you are not using a relay jack. This protects the exposed 87a terminal which will be an unfused "hot" anytime the ignition is OFF. If you are using a plug it will protect the unused terminal.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
|
| Back to top |
|
|
Junkyardjockey
Samba Member
Joined: April 15, 2013
Posts: 883
Location: Utica,NY
|
| Posted: Sat Mar 09, 2024 2:09 pm Post subject: Re: Switched Fuses |
|
|
| ashman40 wrote: |
| shakers73 wrote: |
| Thanks, Ashman40. So I can piggy back the #8 input side with a wire to terminal 30 on the relay. Connect another wire from terminal 87 to input side of fuse #7. Then a wire from terminal 85 to ground. Assuming all this is right, what would be a good source to run to terminal 86? Do I need to use 87a? |
That sounds correct.
Connect 86 to either fuse #11 or #12 OUTPUT. This will add a small 0.050A of extra load to the fuse. It should not be a problem for that circuit.
The 87a terminal is only found on the SPDT relay and is the NC (normally closed) circuit connecting to 30 when the relay is OFF. It is not used in this arrangement.
If you really want to be safe, apply some shrink wrap/tubing around the 87a terminal if you are not using a relay jack. This protects the exposed 87a terminal which will be an unfused "hot" anytime the ignition is OFF. If you are using a plug it will protect the unused terminal. |
I have a question Ashman40 & Shakers73-it appears that the fuse & relay panel on the 74 super has 3 slots for a 4 prong relay; shown in the first photo, down from my thumb. As long as you don't use the interlock relay & remove it, these spaces open up.This relay I found (I found 2 btw) in my box of parts (#53; part number 141-951-253B) is a 4 prong relay, and would be able to handle the load. Those relays fit right into the relay bank. Couldn't you use either 85 or 86 for the relay ground, as long as you use the other for the power? Those 2 terminals are connected to the coil inside the relay, so it shouldn't make a difference which side you'd use for the ground; correct? This would make it much easier to connect to these relays, by installing them in the fuse & relay panel. If you have any doubts regarding the ideas I have; please let me know. Thanks in advance!
_________________
Romans 10:9-10
SAVE THE SUPERS!!
1974 Super Beetle Sunroof
2022 Subaru Outback Limited XT in crystal white pearl
2022 Subaru Outback Limited XT in cinnamon brown pearl |
|
| Back to top |
|
|
ashman40
Samba Member
Joined: February 16, 2007
Posts: 15989
Location: North Florida, USA
|
| Posted: Tue Mar 19, 2024 9:08 am Post subject: Re: Switched Fuses |
|
|
| Junkyardjockey wrote: |
| I have a question... This relay I found (I found 2 btw) in my box of parts (#53; part number 141-951-253B) is a 4 prong relay, and would be able to handle the load. Those relays fit right into the relay bank. Couldn't you use either 85 or 86 for the relay ground, as long as you use the other for the power? Those 2 terminals are connected to the coil inside the relay, so it shouldn't make a difference which side you'd use for the ground; correct? |
Correct. 85 & 86 can be used interchangeably. As long as one is grounded and the other is powered with enough voltage to energize the relay coil (often as little as 6v) then the relay should function.
Technically, as long as there is enough voltage difference between the two the relay should energize. If the relay will function with 6v then... 12v+ on one terminal and 6v+ on the other will result in enough potential voltage difference for a 6v activated relay to work.
| Junkyardjockey wrote: |
| If you have any doubts regarding the ideas I have; please let me know. |
Go ahead and make use of those old relays. 
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
|
| Back to top |
|
|
OTTO 1303
Samba Member
Joined: March 17, 2020
Posts: 638
Location: Louisiana
|
| Posted: Tue Mar 19, 2024 9:57 am Post subject: Re: Switched Fuses |
|
|
Jump BOTTOM of Fuse 12 to BOTTOM of Fuse 7 as shown
Insert 8A fuse at Slot 7 and connect ACC wire to TOP of Fuse 7.
This will give you SWITCHED 12v for ACC.
Good Luck
_________________
74 Super Sun Bug - OTTO
74 Super - DANZIG
74 Super - HERZOG |
|
| Back to top |
|
|
ashman40
Samba Member
Joined: February 16, 2007
Posts: 15989
Location: North Florida, USA
|
| Posted: Wed Mar 20, 2024 5:42 am Post subject: Re: Switched Fuses |
|
|
| OTTO 1303 wrote: |
Jump BOTTOM of Fuse 12 to BOTTOM of Fuse 7 as shown
Insert 8A fuse at Slot 7 and connect ACC wire to TOP of Fuse 7.
This will give you SWITCHED 12v for ACC. |
This does functionally give you switched 12v at fuse 7, but adds to the load on the black #15 wire coming off the ignition switch. The internal #15 contacts in the ignition switch are further stressed by what ever load you add to fuse #7; resulting in premature ignition switch failure.
Adding the relay pulling high amp power from fuse #8/#9 means not adding to the ignition switch load. The low amp draw (85/86) from the 4-prong relays (100mA) adds a much smaller load to the ignition switch contacts.
Taking this to the next step... add the relay between the black ignition switch #15 wire and the fuse box. The 87 output of the relay powers #7, #11 and #12 fuses. This drastically reduces the current flow thru the igniton switch extending the life of the internal contacts.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
|
| Back to top |
|
|
OTTO 1303
Samba Member
Joined: March 17, 2020
Posts: 638
Location: Louisiana
|
| Posted: Wed Mar 20, 2024 10:22 am Post subject: Re: Switched Fuses |
|
|
| ashman40 wrote: |
| OTTO 1303 wrote: |
Jump BOTTOM of Fuse 12 to BOTTOM of Fuse 7 as shown
Insert 8A fuse at Slot 7 and connect ACC wire to TOP of Fuse 7.
This will give you SWITCHED 12v for ACC. |
This does functionally give you switched 12v at fuse 7, but adds to the load on the black #15 wire coming off the ignition switch. The internal #15 contacts in the ignition switch are further stressed by what ever load you add to fuse #7; resulting in premature ignition switch failure.
Adding the relay pulling high amp power from fuse #8/#9 means not adding to the ignition switch load. The low amp draw (85/86) from the 4-prong relays (100mA) adds a much smaller load to the ignition switch contacts.
Taking this to the next step... add the relay between the black ignition switch #15 wire and the fuse box. The 87 output of the relay powers #7, #11 and #12 fuses. This drastically reduces the current flow thru the igniton switch extending the life of the internal contacts. |
Good point.
I only have gauges and LED DRL’s on Fuse 7.
Anything else will get a relay, switched by Fuse 7.
_________________
74 Super Sun Bug - OTTO
74 Super - DANZIG
74 Super - HERZOG |
|
| Back to top |
|
|
|
