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Key not cranking engine - why solenoid under rear seat ?
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Bugnooby
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PostPosted: Sun Oct 17, 2021 4:18 am    Post subject: Key not cranking engine - why solenoid under rear seat ? Reply with quote

Hello All - new VW owner so please be gentle with me, I bought my dear wife a ‘74 Super Beetle and appears that I have a lot to learn. The ignition key will not crank the engine, but I can jump the points on the solenoid shown in the image and it fires right up . I just got it home late yesterday evening and haven’t crawled under to see the starter yet, but I’m having difficulty understanding why this solenoid is even under the seat? All the comments I’ve found indicate the solenoid is on the starter and there should be a wire junction only under the seat to jump from the battery for troubleshooting. Why would there be a solenoid in this location ? Thanks for any input you might have
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Pops67Beetle
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PostPosted: Sun Oct 17, 2021 5:20 am    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

I would imagine that the solenoid on the starter (where it should) is shot. The wiring in your photo is a train wreck of multiple possible solutions. Start by checking that there is voltage from the start wire from your ignition switch to the solenoid. Hook up a 12v light bulb to it and see if it lights with the key in the start position. If you have voltage to the start wire then you have to decide if you want to replace the starter or repair it. If there is no voltage to the start wire then you need to see if it is the wire or the ignition switch.
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Bugnooby
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PostPosted: Sun Oct 17, 2021 5:50 am    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

Thanks Pops67Beetle..I did put a multimeter on the smaller red wire on the solenoid and turned the switch. No voltage, only a couple red dash lights turn on. So it would seem power is getting to the switch but not back to this solenoid. Does the line from the switch to the solenoid typically have a fuse?

Thanks for your help.
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Pops67Beetle
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PostPosted: Sun Oct 17, 2021 6:09 am    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

I don’t believe there is a fuse on the start wire. Sounds like you are going to have to check for voltage at the connector from the ignition switch to see if it is a switch issue or a wire issue. If you have voltage coming out of the switch but not to the solenoid try a jumper wire. You should download a wiring diagram from the Samba’s technical section if you don’t already have one.
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67 Beetle bought new, 95% stock.
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Bugnooby
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PostPosted: Sun Oct 17, 2021 7:18 am    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

Well, there is constant power in the red wire at the switch connector , but nothing in the heavy red/white wire when key is turned. I can put a fused jumper wire between the two and it cranks the engine over ..doesn’t start but does turn it over well. This would seem to indicate the switch is bad ...would you agree ?

Thanks again
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volksworld
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PostPosted: Sun Oct 17, 2021 8:34 am    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

ok the solenoid you see under the seat is from a 70's ford...it was wired in as a "hard start relay"....as bugs get old resistance builds up in the circuit from the key to the real solenoid on the starter...the solenoid you see is put there to bypass the original wiring....a new hot lead from the battery goes to one side, a new hot lead goes from its other side to the solenoid on the starter...and the ford solenoid is triggered by the original key-to-starter lead....it takes much less juice to get the ford solenoid to engage and the new hot leads now feed enough juice into the actual starter solenoid to get it to engage...technically the car doesnt need it but installing one is easier and cheaper than getting to the root of the actual problem (like a whole new wiring harness for instance)...since the starter engages when you jump it out its ok and the problem exists between the small terminal on the booster and the key....disconnected on the other end, bad ignition switch, no power into the ignition switch etc...grab your test light and go for it...jumping out the red wires on the ignition switchwill crank the starter but the car wont actually start without power to the black wire that goes to the coil

Last edited by volksworld on Sun Oct 17, 2021 7:43 pm; edited 1 time in total
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volksworld
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PostPosted: Sun Oct 17, 2021 8:59 am    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

oh and checking stuff like this is easier with a test light than a multimeter...a bright light on the test light will generally show a good connection where a meter can show that 12v is getting through but virtually no amps are flowing
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Bugnooby
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PostPosted: Sun Oct 17, 2021 4:52 pm    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

Thanks everyone. Still some digging to do but narrowing it down. I discovered that I can turn the key to start and jump from the feed wire on the solenoid to the hot side of the battery and it starts right up. Now if I can just keep my wife from running up and down the street in it long enough for me to finish. Fun little car.
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Busstom
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PostPosted: Sun Oct 17, 2021 5:32 pm    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

Just so everyone is clear on this, including any future readers: there ARE no solenoids under your back seat, those are ALL relays, plain and simple. You guys are all jumbling terminology which is confusing matters.

A solenoid is an electromagnet which converts electricity into some form of mechanical motion with a plunger/actuating rod. And thus, the only solenoid present on your car, is on the starter, and it is indeed STILL working, you said as much because you said you got the car to start. You absolutely cannot put a solenoid anywhere in/on the vehicle other than ON the starter and expect it to somehow mysteriously reach out to the starter and push out the bendix in your starter and crank the engine. That is why the solenoid MUST be on the starter, it must physically touch and actuate the bendix to crank the engine.

The hodge podge of relays under the seat are a compilation of clumsy, misguided attempts to correct a low current problem of getting power from your starter switch to the starter, as was alluded to earlier. I'm not against relays for starters, but the example you posted is a total mess. They should all be removed and you should start from scratch with the original wiring and see if it even works that way. THEN add a relay, fused and wired cleanly/correctly, if needed, near the battery, ideally using one of the methods defined in some of the many threads in these forums which discuss the topic.

Did I already say the ONLY solenoid on that car (other than maybe on the carb) is on the starter?
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OTTO 1303
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PostPosted: Sun Oct 17, 2021 6:11 pm    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

Definitely looks like band-aids in the form of a hard start relay and external starter solenoid.
Now you have problems with the repairs someone else performed to attempt to remedy problems.

Research the wiring of a hard start relay and why it is used and VERIFY that the starter solenoid that is on the starter is actually bad.

You may be able to simplify the circuit and be closer to original setup.

Good Luck
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PostPosted: Sun Oct 17, 2021 6:55 pm    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

Busstom wrote:
Just so everyone is clear on this, including any future readers: there ARE no solenoids under your back seat, those are ALL relays, plain and simple. You guys are all jumbling terminology which is confusing matters.

A solenoid is an electromagnet which converts electricity into some form of mechanical motion with a plunger/actuating rod. And thus, the only solenoid present on your car, is on the starter, and it is indeed STILL working, you said as much because you said you got the car to start. You absolutely cannot put a solenoid anywhere in/on the vehicle other than ON the starter and expect it to somehow mysteriously reach out to the starter and push out the bendix in your starter and crank the engine. That is why the solenoid MUST be on the starter, it must physically touch and actuate the bendix to crank the engine.

Did I already say the ONLY solenoid on that car (other than maybe on the carb) is on the starter?


I'm glad you clarified this because it drives me #%&%$@#%*&#$#%^%& nuts trying to decipher what folks post sometimes !!!

Typically folks post "she won't turn over" and I refer them to a sex counselor, because I cannot tell if that's the issue, the engine won't crank/spin at all, or it spins/cranks and just won't start.

And is it that really that difficult to know what a hex head screw/bolt is compared to a stud or a nut????
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volksworld
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PostPosted: Sun Oct 17, 2021 7:23 pm    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

yes except the ford solenoid under his seat IS called a solenoid by every ford owner, service manual and parts book in the world...so anyone who has worked on more than one kind of car in his lifetime knows what he's referring to....in this case its being used as a relay...and that isnt an awful jumble of wires...someone simply mounted a new rear defogger relay in there without removing the old one....the wiring of both devices under there is completely independent of each other...the other couple of wires are abandoned ones from the factory diagnostic plug in the engine compartment...this is what a daily driver looks like
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ashman40
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PostPosted: Sun Oct 17, 2021 7:52 pm    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

Busstom wrote:
A solenoid is an electromagnet which converts electricity into some form of mechanical motion with a plunger/actuating rod.

Totally agree with your description. Smile

Unfortunately, you are incorrect about those larger style relays used in Fords and Dodge cars from the '60s and '70s. While they function as a relay... internally they have a coil of wire (electromagnet) that actuates a plunger to close the contacts between the two large studs. I'm not certain all of the large relays work this way but definitely some do. Since they use an electromagnet to create motion they are definitely a solenoid, as well as a relay.

Here is a YouTube video that tears one of those Ford style solenoids apart. You can see the electromagnet and the steel cylinder that slides in/out to push on a pin that closes the contacts.

Link



IMHO, those large relays/solenoids are not a good choice for a HSR. There is already a solenoid on the starter. The solenoid pictured above draws nearly the same current to energize. So the Ford style relay as a HSR does not do much to reduce the current over the #50 wire. The smaller black Bosch style relay shown as the replacement defroster relay is a much better candidate for a HSR.


To the OP, if your ignition switch #50 wire has zero voltage when the key is turned to the 3rd START position you will need a new ignition switch electrical part. You will need to remove the steering wheel to access the ignition switch at the bottom of the steering column housing.
Also, replace that solenoid with a Bosch-style relay (like the black box one under the seat) as your HSR. Aftermarket ignition switches need an HSR to last more than just a couple years.
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PostPosted: Sun Oct 17, 2021 9:34 pm    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

^^^ Okay you guys got me there, you can tell I've NEVER used a Ford "solenoid," nor done much work on Ferds. But there's still no way thay Ferd "solenoid" is gonna kick out that bendix, so it's really nothing more than a relay, the only solenoid that matters is the one on the OP's starter Wink
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PostPosted: Mon Oct 18, 2021 12:14 am    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

I've always heard 'relay' used to describe a relatively low amp electromagnetic switch, driven by a solenoid internally.. what seems more appropriate for the electrical item in question would be 'contactor.'
It is not bad to have one. My personal opinion is that if anyone wants to use a hard start relay, a low current draw relay (IE, typical 30/40A Bosch 4/5 pin) is ideal. What is pictured is NOT low current draw... it will burn the ignition switch contacts just as quickly as the starter mounted solenoid contactor.
I would highly recommend covering up all the red and red/white terminals.. red is hot from the battery at all times, red/white is only hot when ignition is switched to 'start;' then you have black, which is powered only with the ignition in on/run. There should not be a fuse in line, or a better way to put it, a fuse in that run of wire is not stock from VW. The wiring diagram shows connectors in in line, T6 and possibly T20, but I can't read the last number very well.

Ignition switches are a common failure point. You can disassemble and repair some of them, some times. The next place would be the crimped on terminals which are also known for heavily corroding and causing a voltage drop. I don't have a super so I don't know for sure but it looks like there is a connection point in the column multi function switch as well.

https://www.thesamba.com/vw/archives/info/wiring/73-only113wiring.jpg
https://www.thesamba.com/vw/archives/info/wiring/73-only113wiring-key.jpg
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volksworld
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PostPosted: Mon Oct 18, 2021 10:07 am    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

Busstom wrote:
^^^ Okay you guys got me there, you can tell I've NEVER used a Ford "solenoid," nor done much work on Ferds. But there's still no way thay Ferd "solenoid" is gonna kick out that bendix, so it's really nothing more than a relay, the only solenoid that matters is the one on the OP's starter Wink
....ok just to break your chops some more...a bendix is a spring loaded drive(invvented by victor bendix over 100 yrs ago) that sends the starter gear into the flywheel just by the action of the starter motor spinning...and thats what fords used...so their solenoid was just an electrical contact....so of course people started(incorrectly) referring to any means of causing the starter gear to engage the flywheel as a bendix
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PostPosted: Mon Oct 18, 2021 10:27 am    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

To give you an idea of the currents involved...
    Current to energize a Bosch box relay = 0.05A ~ 0.10A
    Current to energize the Ford style relay (solenoid) = 10A~15A
    Current to crank the starter motor = 100A+


The stock VW arrangement had the ignition switch passing the 10-15A needed to energize the starter solenoid. Over time this burns the electrical contacts in the ignition switch. It gets harder and harder to get the starter to engage and crank. The OE German ignition switches lasted years/decades. The current batch of aftermarket switches only last months/years before their contacts get burnt and stop working reliably.

Adding the Bosch relay as a HSR on the #50 circuit means the ignition switch now only needs to pass 0.1A to energize the Bosch relay. The inexpensive (less than $5 in some cases) Bosch-style relay carries the 15A needed to energize the starter solenoid. The starter solenoid passes the 100A+ from the battery cable to the starter motor to get the engine cranking. The HSR arrangement is basically a switch powering a relay which powers another solenoid/relay to energize the starter motor.


The starter solenoid mounted to the starter motor has two functions... it is a high amp relay passing direct battery current to the starter motor and it is also a solenoid that extends the Bendix drive pinion gear to engage the ring gear on the flywheel. Here is a good video that breaks down how the solenoid/starter functions. There are lots of little interesting details well explained with animated videos.

Link

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PostPosted: Mon Oct 18, 2021 2:24 pm    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

volksworld wrote:
...referring to any means of causing the starter gear to engage the flywheel as a bendix

Well, that's not exactly what I was suggesting...I always thought the Bendix was the shaft/gear mechanism, but I see what you're talking about now, after looking at diagrams on the Web...

See? Kinda how ashman is using the term here:
ashman40 wrote:
The starter solenoid mounted to the starter motor has two functions... it is a high amp relay passing direct battery current to the starter motor and it is also a solenoid that extends the Bendix drive pinion gear to engage the ring gear on the flywheel.


(now insert kowtow emoji here) Smile
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Bugnooby
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PostPosted: Wed Oct 27, 2021 11:38 am    Post subject: Re: Key not cranking engine - why solenoid under rear seat ? Reply with quote

Thank you all for your input. I did install a new ignition switch and that works (most of the time) I have some Flakiness in the wire connector at the back of the switch that I’ll now work through. Getting ready for front end rebuild and disc brake conversion and preparing the car for paint, and then will cleanup wiring under rear seat and install proper HSR. Thank you all again.
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