push button start
Printed From: the12volt.com
Forum Name: Vehicle Wiring Information & File Requests
Forum Discription: Request Car Alarm, Car Stereo, Cruise Control, Remote Starter, Navigation, Mobile Video, and Other Vehicle Specific Wiring Info, Manuals, Tech Tips
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=116130
Printed Date: May 13, 2025 at 6:48 PM
Topic: push button start
Posted By: wrinkles
Subject: push button start
Date Posted: September 06, 2009 at 7:52 AM
Hi
I have a '99 Volkswagen Polo 1.9 SDI 4 door. Ancient but Good.
The ignition switch is faulty in that when turned to the 'start' position, 9 times out of 10 nothing happens. I have established that it is the switch that is faulty and intend to bypass the 'start' position by installing a push button start ie turn on ignition then push start button to engage the starter.
I think the wire I need to tap into is red and black (at ign switch), I will connect that to one side of the push button... what do I connect the other side of the push button to? Your advice on this would be much appreciated
My thanks in advance
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If it aint broken, fix it 'til it is
Replies:
Posted By: cormiermc
Date Posted: September 06, 2009 at 10:02 AM
you have the choice,direct 12 volt or ignition switched with a relay. i suggest ignition cause direct 12 volt will let the starter run even with the key off. don't forget to turn off accessory during start.
Posted By: tommy...
Date Posted: September 06, 2009 at 10:05 AM
Defitnely not the starter or solenoid...ey...? If the wire you need is RED / black...i assume this is your starter wire...? You can use a switch to activate a relay...then the relay supplies power to the starter wire...I have never added a push-to-start...But i guess you could use a momentary switch...One side to the RED / black...The other side to a good power(12v) source...Make sure you fuse the power wire...Also...you will have to make sure the momentary switch is capable of handling the input/output...And if you want to get really crazy...there are some diagrams on here for using the one button to power up everything...Acc...ign's...etc...!
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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
Posted By: howie ll
Date Posted: September 06, 2009 at 3:58 PM
Most push switches won't handle the juice in that wire you're safer like this:- push button switch, one side to ground, (earth), other side to relay 85, ignition (black wire) to 86, constant 12volt+ (thick red) fused at 30 amps to 30, starter output (RED / black) to 87. N.B. remove glovebox, oup to right, there's the loom (assuming this is a UK r/h/drive spec), they are all in that loom, even ground wires (plain brown) or heater grounding bolt at the top of the passenger kick panel (look to the left), then mount the push switch in the glove box, easy wiring with short leads, push button in glovebox = more security.
Posted By: wrinkles
Date Posted: September 07, 2009 at 10:36 AM
Apologies for the delay and thanks for the input.
Please bear with me as I'm not too familiar with vehicle wiring.
I had assumed that, the RED / black wire, which is(?) the starter wire, already goes to a relay, as it's not heavy enough to take full starter load.
This being the case then the switch will, when turned to the start position, connect this wire to something which completes the circuit. Could that be ground/earth? Or am I completely off track here.
Howie II, I liked the sound of your advice but I'm afraid I lost the plot after "other side to relay 85". A slightly more explanatory version in words a moron like me could understand might help. As I read it, and as I have only two connections on the button, I connect one side to ground the other to relay 85. The rest?????
Cormiermc. "don't forget to turn off accessory during start." that sounds ominous, what are the implications there.
And I thought this would be a simple task.
To recap. When I try to start the car, if I'm lucky and hold the key in just the right position the starter operates as normal, most other times nothing the key turns the starter doesn't engage. Extensive investigations confirm the ignition switch is at fault. Yes I could fit a new ignition switch but the DIY job is fraught with problems and my local dealer(should that be stealer) would charge more than the car is worth. So a cheap but effective fix is required. For anything else I would chop a few wires and use trial and error but in this case if I blow it I could lose the only way I currently have of starting the thing.
Again thanks for the help so far and I will await anything further
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If it aint broken, fix it 'til it is
Posted By: tommy...
Date Posted: September 07, 2009 at 3:03 PM
Well...If you have a meter...You can check to see if there is voltage on the starter wire during crank...If not...Can probably assume its the cylinder...On the other hand...It should not be that hard to wire up something to just crank starter wire...Alot cheaper too...! A buddy did one on his daily driver...Was just a momentary switch...Picked up at local parts store...I have used a few momentary switches in airhorn applications w/ no problems.(i would think a starter is a little higher up on the current scale)..I believe i used a ground output...Been awhile...
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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
Posted By: wrinkles
Date Posted: September 08, 2009 at 6:04 AM
Yes Tommy that's all I need. I have a purpose made "Start" button, and need it to crank the Starter/engine by replacing the connection made through the key switch which I have established is faulty. In order to do this I need to know, having tapped into the black & Red wire at the ignition switch and connected to one side of the push button, where to connect the other side of the button? Does it go to ground or to live?
or is there more to it than that?
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If it aint broken, fix it 'til it is
Posted By: tommy...
Date Posted: September 08, 2009 at 9:25 AM
Well since we have not verified that is the starter wire...Maybe you can see why i am hesitant...But the other side of the switch would go to...Ignition wire or 12 volts......If you use the ignition wire , it can only crank when key is turned on...! Lets verify that is the starter wire...And you will need to verify the ignition wire...Make sure you fuse the side of the switch that is attached either to ignition or constant...! Now on dropping accessory...When you turn the key to the crank position...Does all of your accessories turn off...If so...You could just crank the key while pushing button...! Now i really wish you would go get a multi-meter...This would tell us exactly whats going on...And make me feel better...  ------------- M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
Posted By: tommy...
Date Posted: September 08, 2009 at 9:26 AM
howie ll wrote:
Most push switches won't handle the juice in that wire you're safer like this:- push button switch, one side to ground, (earth), other side to relay 85, ignition (black wire) to 86, constant 12volt+ (thick red) fused at 30 amps to 30, starter output (RED / black) to 87. N.B. remove glovebox, oup to right, there's the loom (assuming this is a UK r/h/drive spec), they are all in that loom, even ground wires (plain brown) or heater grounding bolt at the top of the passenger kick panel (look to the left), then mount the push switch in the glove box, easy wiring with short leads, push button in glovebox = more security.
------------- M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
Posted By: tommy...
Date Posted: September 08, 2009 at 9:32 AM
Instead of constant 12v on 86...Repace w/ ignition...(per Howie)...!!! So one side of switch goes to ground...the other side of switch is going to pin 85...! If you have a switch or an alarm or keyless entry that has a negative output that you wish to use to switch a device that requires 12V+ such as a horn, dome light, parking lights, head lights, hatch release, etc., wire a relay as shown below to convert the negative output (trigger) to a positive output.  ------------- M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
Posted By: wrinkles
Date Posted: September 08, 2009 at 10:24 AM
tommy... wrote:
Well since we have not verified that is the starter wire...Maybe you can see why i am hesitant...But the other side of the switch would go to...Ignition wire or 12 volts......If you use the ignition wire , it can only crank when key is turned on...! Lets verify that is the starter wire...And you will need to verify the ignition wire...Make sure you fuse the side of the switch that is attached either to ignition or constant...! Now on dropping accessory...When you turn the key to the crank position...Does all of your accessories turn off...If so...You could just crank the key while pushing button...! Now i really wish you would go get a multi-meter...This would tell us exactly whats going on...And make me feel better...
Thanks Tommy, It looks as though I am going to have to get a grip of myself and sort this out. I have a multimeter but once I have the column cowl off and can see the base of the ignition switch. There is no room to get a probe to the BLACK/ red wire at that point. The wire and plug it goes into are too tight up against the column. There was no free play and I was reluctant to go cutting anything for, as I said, I don't want to louse up the only means I have of cranking the car, hit and miss as it may be. I have an idea thought, and at my next attempt I will push a pin through the wire and connect that to the meter which will give me the information required regarding that wire. Unfortunately I won't be able to do anything for the next couple of days as I'm going to be away. However on my return I shall throw caution to the winds and do a bit of slicing and splicing. If I survive the inevitable flash fire I will return and post the result -------------
If it aint broken, fix it 'til it is
Posted By: howie ll
Date Posted: September 08, 2009 at 2:47 PM
The ignition wire on that vehicle is only about 1mm (18 gauge?) whereas the starter is 2.5mm dia. suggest a relay coil energised via the ignition and a 30amp feed to the relay, grounding the relay through the switch. Wait I've said all this before.
Posted By: tommy...
Date Posted: September 08, 2009 at 7:10 PM
Stop...Drop...and Roll...!
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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
Posted By: wrinkles
Date Posted: September 12, 2009 at 8:42 AM
Right then I'm back.
having had another look at the ign switch wiring, multimeter in hand I have established the following wires
Red (hot)
Black (Hot when Ign on)
Red / Black (no power ign on or off)
* Black / YELLOW
* Black / White
* Red / Brown (2)
I was unable to get to the wires marked * whilst they were plugged into the ign switch. on removing the plug none had power to them.
Replacing the plug I connected the RED / Black to Red with no effect,
likewise the RED / Black to Black (ign on) no effect.
My Logic dictates that by connecting two or more of these wires together should result in the starter cranking. Unable to get a specific wiring diagram for this model I have checked with various other VW polo models and from the scant information available RED / Black is always indicated as STARTER.
i.e as indicated here
Polo .
However despite searching the net I can't find a definitive diagram of the ign switch wiring
To be honest it's all Greek to me but I assume one of you learned gentlemen will understand it enough to point me in the right direction. Hopefully that direction will not be out into the wilderness.
I appreciate your efforts and accept I am a pedantic old fart but I am sure the job can be done this way rather than extensive wiring to relays and fuse boxes wherein I am likely to blow the whole electrical system.
Failing your help I'll have to save up my pension and go see an Auto electrician and help buy him a retirement home in sunnier climes.
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If it aint broken, fix it 'til it is
Posted By: wrinkles
Date Posted: September 12, 2009 at 10:27 AM
Hold the phone, I did it. I now have a push button start and it works.
Very simple too.
Simply connect one side of the push button to the Black lead at the ignition switch. The other side of the switch is connected to the BLACK/ red wire. Turn on ign push button, engine cranks.
This I tried earlier today but got nothing but after further investigation I found the connection I had made at the ignition switch B/R wire was bad. Redid the connection with a scotchloc connector and I was in business
Many thanks to you for your input, sorry I was such a moron but the outcome was satisfactory and now anyone else with the same problem has a fix  -------------
If it aint broken, fix it 'til it is
Posted By: howie ll
Date Posted: September 12, 2009 at 12:42 PM
A scotchlock? Banned from use it's not passing enough juice and it won't last, SOLDER. Your ignition switch should have the following:- Red = 12v+ constant BROWN / Red = ACC, dumps while cranking Black = Ign 1 ( live whilst cranking) BLACK / YELLOW = Ign 2 (dumps when cranking) BLACK/ Red = Starter NO BLACK/ white
Posted By: tommy...
Date Posted: September 12, 2009 at 3:09 PM
T-Taps...Scotch-Locks...NO..NO...Especially in high current applications...! Did you fuse the one side of the switch wire that is attached to either 12v or Igntion...?
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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
Posted By: wrinkles
Date Posted: September 12, 2009 at 4:50 PM
 Ah! Sorry I should have added that the scotchlocs were only used to tap into the wires whilst I figured it out and were removed once I had determined the connections. As it was too tight to get a soldering iron into the space available I had to make do with connector blocks that were secured and taped. Although the resulting circuit should still run through the original fuse I added another one in line just to be on the safe side. I then cranked the engine for about 30 seconds and checked for undue heat in the wires. There was none so I am relatively happy that it is "job done".
Oh! and there is a Black & White wire which goes into the plug to the ign switch. I don't know what it does but it appears to be OEM. Maybe part of the diesel configuration.
Sorry if I gave you palpitations and visions of my old heap bursting into flames. I may not be very bright but completely stupid I'm not. Even though 'er indoors would probably disagree.
Again many thanks for your help and concerns. I know where to come if I require more assistance in the future. (Do I hear sounds of grown men crying, Shouting NO NO and running for the hills?)
You are all stars -------------
If it aint broken, fix it 'til it is
Posted By: tommy...
Date Posted: September 12, 2009 at 5:16 PM
I know in amp installs they say if you use a dist. block and its 4 gauge coming in...And 8 gauge going out...If the dist block is not fused ...Then you have to fuse each of the 8 gauge outputs...In most cases, the wire size is reduced at the point of distribution. ANY time that the wire size is reduced, you must add a fuse in the line (at the point of distribution) to protect the smaller wire... Anytime you tap into a 12v source...you fuse...! And Congrats on finishing the install...! https://bcae1.com/wire.htm ------------- M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
Posted By: tommy...
Date Posted: September 12, 2009 at 5:28 PM
Come anytime you have questions...The first one is always free...!
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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
Posted By: wrinkles
Date Posted: October 30, 2009 at 12:14 PM
Hi again
Just as an up date. I was unable to find a suitable location to install the push button. Anywhere that I wanted to put it the trim panel was too thick or there was something behind it. Finally I decided to change the approach and got a small heavy duty toggle switch, (spring loaded) I drilled one of the switch blanks below the heated rear screen and the hazard warning switches. Set the toggle switch into it a replaced the blank. It relocated firmly so no fear of it coming adrift and I've been using it successfully for the past 6 weeks or so. Turn on the ignition and press the switch and she cranks, when she fires up release the switch. Job done and it's a good un!
Again many thanks for your input it was very helpful
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If it aint broken, fix it 'til it is
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