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runamoc 
Samba Member
Joined: June 19, 2006
Posts: 5610
Location: 37.5N 77.1W
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 Posted: Thu Feb 20, 2020 12:32 pm Post subject: Re: Hard Start Relay Diagram |
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| UK Luke 72 wrote: |
| Do these actually help the starter turn any faster or do they just take current away from the ignition switch and also make it easier for the starter gear to mesh? |
They do both. Wire has resistance. Long wire has more resistance than a shorter wire of the same gauge. Less resistance means more voltage and current to the load thus a faster spinning starter motor. It helps the ignition switch by removing the high current load needed to 'magnetize' the stock solenoid and substitutes the lower current needed to operate the added relay.
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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 |
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Eric&Barb
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Joined: September 19, 2004
Posts: 24806
Location: Olympia Wash Rinse & Repeat
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| Posted: Thu Feb 20, 2020 12:55 pm Post subject: Re: Hard Start Relay Diagram |
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| UK Luke 72 wrote: |
| Do these actually help the starter turn any faster or do they just take current away from the ignition switch and also make it easier for the starter gear to mesh? |
Hmm, if someone starved you of food for a few weeks, would you be able to run, jump, climb as fast as you would if you had been fed properly?? A great military leader of a country once said that "An army travels on it's stomach". Starters and the starter solenoids travel on the voltage and amperage that get to them and back to the battery! Limit either or both and they will slow down or even STOP working.
These starter AKA hot start relays bypass the wiring going from the battery connection on the starter solenoid up to the fuse box, on to the ignition switch and back to the starter. So if there is any voltage drops in the wiring or especially the connections this no longer affects the starter solenoid from not getting full voltage and amperage from the battery.
Problem is if the voltage drop/s are anywhere from the battery cable connection on the starter solenoid on to the fuse box, to ignition switch, those will still affect electrical systems like coil, turn signals, wipers, horn, lights from operating very well or at all. Plus if the starter is struggling due to low voltage getting to it and bad grounds, it will pull more voltage away from the coil. If coil is not getting as much voltage due to loose/corroded connections going to it already, you will get weak or no spark for the engine!
So the relay will not fix those problems or fix bad connections due to bad (as in loose and/or corroded) battery cables or bad/missing ground cable from transaxle to body, or even bad ground connections between the starter and transaxle and/or between the starter solenoid and the starter itself.
These last two caused us a lot of grief for quite a while with our 1963 single cab still running 6 volts that does not get daily driven. Would only start in the morning with being jumped from another vehicle. Without a jump it would not even get a click from the starter solenoid. Then it would start and run just fine for the rest of the day, till next morn it needed a jump again. Went thru with voltage meter checking and cleaning all the wiring connections till there was little to no voltage drops. That improved it during warm weather (battery needed to be on charger over night to be able to start), but when cooler weather came it needed again the morning jump. Cleaned the starter and transaxle surfaces and applied dielectric grease to keep corrosion away for as long as possible into the future by keeping oxygen and moisture away. That made a big difference often not needing the battery charged up for a day or two, but that slipped back to needing it on the charger over night again. Finally removed the starter to clean and dielectric grease the ground connection between starter solenoid and starter body. Now can leave the SC off the charger for over a week and starter will engage right off with key turn and engine turns over nice and fast.
Personally have only seen one VW that needed a starter relay. A nice Kombi Bus that the larger wire between the ignition switch to the starter solenoid had been somehow shorted out by DPO and fried the wire strands in the wire into a much thinner less capable to move amperage/voltage to get the solenoid to work.
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Eric&Barb
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Joined: September 19, 2004
Posts: 24806
Location: Olympia Wash Rinse & Repeat
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| Posted: Thu Feb 20, 2020 1:23 pm Post subject: Re: Hard Start Relay Diagram |
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Should also mention that the starter solenoid not only levers the starter gear to the rearward to engage the flywheel gear, but it also has a plate switch inside the solenoid. When that switch is closed in the solenoid, the electrical power from the terminal the positive cable is attached to solenoid is suddenly connected to the starter motor. So if there is any voltage drops from the positive connections from the battery to the solenoid or voltage drops in the several ground connections from the solenoid to the battery ground terminal. Then the solenoid will pull weakly, and the switch inside will only lightly touch the contacts. This light contact switch touch will limit the voltage/amps passing thru to the starter motor copper windings. Resulting in a starter motor that turns the engine over slower or not at all.
A starter solenoid that gets full voltage and amperage to it should clamp the inside switch contacts TIGHTLY inside. Starter motor will then get as much power available thru that switch.
Starter solenoids can and by this time with so many decades on them should be taken apart and the brass plate inside flipped over to the unworn side. Then clean off all corrosion and dielectric grease lightly. This does require a good high wattage electric soldering iron, or an old fashioned soldering iron over a torch to unsolder the electrical connections in the forward end cover of the solenoid.
So the ignition switch does not directly have any voltage/amps going from it to the starter motor itself.
Like any chain, it is only as strong as the weakest link. So it only takes one bad electrical connection.
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Last edited by Eric&Barb on Thu Feb 20, 2020 1:41 pm; edited 1 time in total |
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UK Luke 72
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Joined: September 07, 2011
Posts: 2867
Location: Little Britain
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Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 24806
Location: Olympia Wash Rinse & Repeat
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| Posted: Thu Feb 20, 2020 2:08 pm Post subject: Re: Hard Start Relay Diagram |
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Here (found in the Gallery by VolkDubz) is what the contacts of the solenoid insides looks like:
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ashman40
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Joined: February 16, 2007
Posts: 16001
Location: North Florida, USA
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| Posted: Thu Feb 20, 2020 3:26 pm Post subject: Re: Hard Start Relay Diagram |
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| UK Luke 72 wrote: |
| Thanks for the input guys, I'm going to dig the Bentley out so that I can get my head around how the starter circuit works. |
I found this pic showing the function of the starter circuits and the Bendix drive of the starter.
The part of the diagram with the "start switch" actually runs about 20-30ft with the switch being inside the ignition switch.
When you install an HSR below the rear seat that distance drops to around 3ft. This greatly reduces the voltage loss in the circuit due to wire resistance.
The switch marked "shorting switch" are the large contacts in the pic above of the inside of a solenoid. When the solenoid is energized the brass bar on the left closes the circuit between the two contacts inside the black end cap (on the right). These black cap contacts are the inside end of the two large studs visible on the outside of the solenoid. One is for the battery cable, the other is to the cable that runs to the starter motor itself.
| UK Luke 72 wrote: |
Whilst cranking, Im seeing around 10v on the ECU.
12.2v on the ECU is 12.7v on the batter terminals, so whilst cranking I guess around 10.5v. |
Measure the voltage at the battery terminals when there is no load and when the starter is cranking the engine. This difference reflects the strength of your battery. Expect to see a small voltage drop with a new battery (no less than a 12.0v reading at the terminals). On an older battery the voltage reading at the terminals may drop down to 11.0v. These voltage drops reflect the load of the starter motor on the battery and the ability for the battery to carry that load. As the battery goes bad the ability to carry the load is reduced.
Measure the voltage at the battery terminals when the ignition is in the ON/RUN position and compare this to the voltage at different points around the car (eg. ignition coil and ECU). Voltage drops between these measurements represent wire resistance between the battery and the point you are measuring.
Anything more than 0.5v difference can probably be improved by cleaning up wire connections/contacts.
Realize that in the early Beetles the transistor radio was probably the only voltage sensitive device. Everything else was analogue and less sensitive. The ignition coil will work down to around 9.0v, but an aftermarket electronic ignition module will stop working once the voltage drops below 10.0v.
An ECU is probably even more sensitive to a low voltage condition than that. Modern solid state devices are designed for a narrow operational voltage range. With 50yr-old wires resistance in the conductors and connections will reduce the voltage that makes it to the end of the circuit.
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AshMan40
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'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!} |
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Eric&Barb
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Joined: September 19, 2004
Posts: 24806
Location: Olympia Wash Rinse & Repeat
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| Posted: Mon May 04, 2020 4:53 pm Post subject: Re: Hard Start Relay Diagram |
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Any updates??
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herbie1200
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Joined: April 27, 2006
Posts: 833
Location: Rome - Italy
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| Posted: Wed May 06, 2020 2:58 am Post subject: Re: Hard Start Relay Diagram |
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The schematic is more complicated that it seems.
If you look at the solenoid you can see TWO "/" lines, to make and evidence that the solenoid has TWO different windings.
When the key is turned on, the left winding is fully energized because the "up" is at 12V and the "low" contact is on the "live" contact of the starter.
The right winding has the "up" at 12V and the low at ground.
So, at the beginning, the soleonoid has TWO windings on and its strength is double, that is useful for the first "engaging" travel.
When the shorting switch becomes ON, the left winding has both the contacts at the same potential (the motor is ON), so the solenoid has half strenght, and this is to avoid an excessive load when the motor is spinning and the contact is already on. |
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ashman40
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Joined: February 16, 2007
Posts: 16001
Location: North Florida, USA
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| Posted: Wed May 06, 2020 7:08 pm Post subject: Re: Hard Start Relay Diagram |
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| herbie1200 wrote: |
The schematic is more complicated that it seems.
If you look at the solenoid you can see TWO "/" lines, to make and evidence that the solenoid has TWO different windings. |
Good catch.
Here is a good write up on the "pull-in winding" vs. the "hold-in winding" in the solenoid. Agreed it is a bit more complicated... but very cool. 
http://prod.lv2014.gener8cms.net/index.php/70-disc-brakes/section-7/battscs/733-solenoid-operation
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AshMan40
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'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!} |
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todmeg
Samba Member
Joined: November 26, 2005
Posts: 252
Location: new jersey
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| Posted: Fri Apr 19, 2024 4:49 pm Post subject: Re: Hard Start Relay Diagram |
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So th Ghia is in for a body off resto. paint and body work Are done. Body is back on so let the reassembly begin. going well. Since the work is being done at a local really good body/collision shop, I was not involved with r&r on the body. Anyhow, just about all the electrical is up and running, which is more than I can say about cranking. Meanwhile, we have all been wondering WTF this thing hating out that has a relay and a fuse? You Samba guys are the best! Only thing that sucks is that the shop is closed on weekends. Can't wait for Monday! I am blessed with a shop owner who lets me work on my car as much as I want, so I have been involved with everything except paint and bodywork.
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