Which wire is negative?

vrs-si · 26-01-2008, 13:24

right guys im wiring in my boost gauge to my light switch.
theres 2 possibles for neg. black and red or black n white??

which one is it please?

**VRStu** · 26-01-2008, 13:31

Do you have access to a test meter or similar. You can make a suitable tester with a couple of bits of wire and a lamp.

dsmithmobile · 26-01-2008, 13:32

Do you mean which wire on the car is negative? cos if you do then i believe brown would probably be an earth on a skoda but if your unsure then earth it direct to the body of the car behind the dash

vrs-si · 26-01-2008, 13:35

it says wire it to -ve

vrs-si · 26-01-2008, 13:37

i presumed it would be just black

fireftrm · 26-01-2008, 13:54

-ve on all European cars (often excepting French!) and certainly Skoda is brown. Certainly NEVER black, or multi-coloured.

Black and red and black and white are likley to be the two separate side light circuits, live (i.e. +ve) one each for right and left.

My advice go get a manaul (such as Haynes) and a test meter/12v test screwdriver.

PS there are not ususally any earth (i.e -ve) wires going into any switches unless they are lit (in which case the bulb will need an earth contact) as the switch only switches the item on/off. The earth contact is therefore at the item being switched. So a light switch will have only live wiring, main in then different live connections out depending on which selection had been made by the switch. The light then gets a live input and has an earth contact direct to it so it can work. If the switch (like the Octy light swicth) has a lit area so you can see the symbols int he dark, there is usually a tiny bulb, which will need an earth contact, however this will eb a very thin cable and probably not suitbale for nay other purpose than the min-wattage bulb it connects.

The whole bodyshell is -ve (directly connected to the battery -ve terminal) so the earth contacts run to a bodyshell contact. As the dash is all plastic there will be a multitide of brown cables running to earth, so that any lighting, or electrical instruments/radios etc, can work. There is almost certainly a main earth point too, on to the bodyshell, make sure you choose a think enough cable to join to, or run a separate one to a bodyshell contact.

vrs-si · 26-01-2008, 14:26

to when i click it to sides and ive earthed the other black as i found a guide

Basil · 26-01-2008, 14:46

easiest is to identify the fuse supply for the parking lights - tap into the fuse itself by twisting some wire about one of the terminals and stuff the fuse back in(yes I know it's a little rough - but it works).
You can take the negative off any convenient bolt/screw in the body.
IF it's a mechanical gauge with a lightbulb, not an LED, and is insulated from the body in a plastic pod, it doesn't really matter about polarity..

You can make up a tester from a piece of wire and any spare 12V bulb. One end to the body and the other to identify/confirm the fuse. Park lights switched on= tester bulb lights up...

HTH

Bas

vrs-si · 26-01-2008, 15:59

anyone know where ya can get new t pieces from?

26-01-2008, 13:24	#1
vrs-si Briskodian Join Date: Aug 2007 Posts: 565 Members Car: Octavia VRS Thanks: 7 Thanked 6 Times in 6 Posts	Which wire is negative? right guys im wiring in my boost gauge to my light switch. theres 2 possibles for neg. black and red or black n white?? which one is it please? __________________ Skoda Owners are not image concious. 02 Octy VRS SOLD 94 Supra TT GZ now on the drive.

26-01-2008, 13:31	#2
VRStu Txt Spk Police Join Date: Dec 2004 Location: Hampshire Posts: 20,848 Members Car: Audi S3 Thanks: 145 Thanked 1,000 Times in 896 Posts	Re: which wires negative? Do you have access to a test meter or similar. You can make a suitable tester with a couple of bits of wire and a lamp. __________________ Stu Stu's Websites - http://www.fabia-vrs.com & http://www.octavia-vrs.com Stu's Car - 2008 Audi S3 - Ibis White, Black Optics Pack, Privacy Glass, Auto Bi Xenon Headlights, Rain Sensing Wipers, Bose Sound System, Ipod Prep, GSM Phone Prep, Flat Bottom Multi Function Steering Wheel, Electric Folding Mirrors, Acoustic Parking, Cruise Control, Interior Light Pack, Non Smokers Pack. SWMBO's Car - 2008 Seat LEON TDi Stylance, Black Magic, Sports Pack, Rear Parking Sensors. Something for Weekend - A Patio

26-01-2008, 13:32	#3
dsmithmobile Briskodian Join Date: Nov 2003 Location: Hull,East Yorkshire Posts: 1,068 Members Car: 02 black magic octavia vrs Thanks: 0 Thanked 17 Times in 17 Posts	Re: which wires negative? Do you mean which wire on the car is negative? cos if you do then i believe brown would probably be an earth on a skoda but if your unsure then earth it direct to the body of the car behind the dash __________________ my car pics and spec here http://www.cardomain.com/ride/2309233

26-01-2008, 13:35	#4
vrs-si Briskodian Join Date: Aug 2007 Posts: 565 Members Car: Octavia VRS Thanks: 7 Thanked 6 Times in 6 Posts	Re: Which wire is negative? it says wire it to -ve __________________ Skoda Owners are not image concious. 02 Octy VRS SOLD 94 Supra TT GZ now on the drive.

26-01-2008, 13:37	#5
vrs-si Briskodian Join Date: Aug 2007 Posts: 565 Members Car: Octavia VRS Thanks: 7 Thanked 6 Times in 6 Posts	Re: Which wire is negative? i presumed it would be just black __________________ Skoda Owners are not image concious. 02 Octy VRS SOLD 94 Supra TT GZ now on the drive.

26-01-2008, 13:54	#6
fireftrm Briskodian Join Date: Jan 2007 Posts: 85 Members Car: Thanks: 0 Thanked 5 Times in 4 Posts	Re: Which wire is negative? -ve on all European cars (often excepting French!) and certainly Skoda is brown. Certainly NEVER black, or multi-coloured. Black and red and black and white are likley to be the two separate side light circuits, live (i.e. +ve) one each for right and left. My advice go get a manaul (such as Haynes) and a test meter/12v test screwdriver. PS there are not ususally any earth (i.e -ve) wires going into any switches unless they are lit (in which case the bulb will need an earth contact) as the switch only switches the item on/off. The earth contact is therefore at the item being switched. So a light switch will have only live wiring, main in then different live connections out depending on which selection had been made by the switch. The light then gets a live input and has an earth contact direct to it so it can work. If the switch (like the Octy light swicth) has a lit area so you can see the symbols int he dark, there is usually a tiny bulb, which will need an earth contact, however this will eb a very thin cable and probably not suitbale for nay other purpose than the min-wattage bulb it connects. The whole bodyshell is -ve (directly connected to the battery -ve terminal) so the earth contacts run to a bodyshell contact. As the dash is all plastic there will be a multitide of brown cables running to earth, so that any lighting, or electrical instruments/radios etc, can work. There is almost certainly a main earth point too, on to the bodyshell, make sure you choose a think enough cable to join to, or run a separate one to a bodyshell contact.

26-01-2008, 14:26	#7
vrs-si Briskodian Join Date: Aug 2007 Posts: 565 Members Car: Octavia VRS Thanks: 7 Thanked 6 Times in 6 Posts	Re: Which wire is negative? to when i click it to sides and ive earthed the other black as i found a guide __________________ Skoda Owners are not image concious. 02 Octy VRS SOLD 94 Supra TT GZ now on the drive.

26-01-2008, 14:46	#8
Basil Hardcore Join Date: Feb 2006 Location: Bahrain Posts: 3,257 Members Car: Fabia vRS Thanks: 200 Thanked 194 Times in 151 Posts	Re: Which wire is negative? easiest is to identify the fuse supply for the parking lights - tap into the fuse itself by twisting some wire about one of the terminals and stuff the fuse back in(yes I know it's a little rough - but it works). You can take the negative off any convenient bolt/screw in the body. IF it's a mechanical gauge with a lightbulb, not an LED, and is insulated from the body in a plastic pod, it doesn't really matter about polarity.. You can make up a tester from a piece of wire and any spare 12V bulb. One end to the body and the other to identify/confirm the fuse. Park lights switched on= tester bulb lights up... HTH Bas __________________ Fab vRS - Black Magic - PD160 intake - Forge FMIC - colour coded front grille -SLC Splitter - K&N Airfilter -SEAT Strutbrace - Jabba ARB - IC Waterspray (need to wire it in!) - 312mm TT brakes - Eibach Springs - Skoda Reversing sensors - Devonutopia Tuning (tm) Custom Exhaust (2 1/4" straight pipe) - Short shifter mod- 5 brake light mod - Helix Steel SMF + Organic Clutch + pressure plate - Peloquin LSD - TD stage 2 Hybrid - Washbrook remapped ECU - Uprated injectors - Cupra bushes -Poly-filled dogbone - Allard racepipe - Pirelli Dragons - Forge Rear Strutbrace - DIY SS upper boostpipe delete -Koni FSD's - elephant pipe CCV mod

26-01-2008, 15:59	#9
vrs-si Briskodian Join Date: Aug 2007 Posts: 565 Members Car: Octavia VRS Thanks: 7 Thanked 6 Times in 6 Posts	Re: Which wire is negative? anyone know where ya can get new t pieces from? __________________ Skoda Owners are not image concious. 02 Octy VRS SOLD 94 Supra TT GZ now on the drive.

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