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tikiman71 Wed Aug 21, 2019 12:30 pm

Hi, I thought I had bookmarked a thread about this previously but I can't find my previous reference.

Anyway, if one were to install a kill switch on the fuel pump relay of an EJ22 converted Vanagon, would the best way be to interrupt the D23 ECU ground to pump relay wire (light green and black wire, I think...)? If I recall correctly, this would be the safest and lowest amp draw wire to choose from. The purpose is to help deter potential theft.

Thanks in advance!

Adam

DeLvxe Wed Aug 21, 2019 12:51 pm

Following, for sure.

djkeev Wed Aug 21, 2019 1:32 pm

Don't have your answer but....... IMHO....... any wiring you do should maintain the factory look.
Any new wires, any cheapo crimp connectors will just scream "LOOK HERE!! THIS IS WHY IT WON'T START" to any car savy thief.

Even a GPS tracker should be wired totally out of sight and the unit also located out if sight.

On your conversion, do you still have the black box in the LF of the engine compartment?
Do you still use the next black relay box to the rear with the fuel pump relay in it??
If so, I'd work within those boxes for the fuel pump kill.

Dave

Jahbah Wed Aug 21, 2019 2:57 pm

Adam,


You are correct sir, the ground on the fuel pump relay is an easy simple way to immobilize your van. I located the ecu and relays in a small box under the rear seat. There is a small switch inside that kills the fuel pump. The van will turn over like a champ, but will fail to start. In my mind itís an excellent option because there is no monthly cost and without fuel thereís no question your vans in the same place that you left it. Once the van wonít start there not going to troubleshoot, they might steal your stereo or your tools, but not the van. Very easy to do, solder your connections!

I also have a battery isolator for double protection. This is more for electrical safety, but super easy for theft prevention.
Good luck!
D

sdirghalli Wed Aug 21, 2019 6:54 pm

Yeah, I'm following this for sure too!

sdirghalli Fri Aug 23, 2019 6:25 pm

I've added a "hiding in plain sight" kill switch using the rear blower fan switch but now I'm not getting a ground from the ECU going to the fuel pump relay...

I started a new thread in the hopes that someone out there in The Samba land will have some insight!

https://www.thesamba.com/vw/forum/viewtopic.php?p=9153192#9153192

Stefan

newerwesty1987 Fri Aug 23, 2019 6:59 pm

I saw the other thread about the transistor possibly being blown. Is there isa safer or more simple wire to make this work just as well? What about just interrupting the ignition/starter relay wire from the key switch itself? The kill switch could be near by under the dash or in the ashtray, etc.. or even use that rear heater fan switch if possible (mine is also removed from under the rear seat)

fxr Fri Aug 23, 2019 7:21 pm

I just interrupted the ground wiring right at the pump. I used a relay, whose coil used the +12V provided to the pump and was grounded via a simple slide switch, hidden in plain sight once the driver's door is opened.

Easily bypassed if you know how and if either the switch or relay plays up. I doubt a thief would go to the extent of grovelling on the ground and figuring out how to bypass it. ;)

If you want a picture of the switch location, PM me.


newerwesty1987 Fri Aug 23, 2019 7:50 pm

Thanks, but, why not just switch the ground with the switch? The amp load wouldn't be an issue and it would make it more simple.

drj434343 Fri Aug 23, 2019 9:28 pm

I have two kill switches in two different vans both directly connected to the pump ground. I've been using them daily for years without any issues. No relays, just switches directly in line with the pump chassis ground, sometimes extending the ground path length by 30 ft (to and from the switch).

crazyvwvanman Sat Aug 24, 2019 4:43 am

Why do you say that the amp load won't be an issue?
The exact same amps flow through the pump ground wire as through the pump power wire. The added switch and ground wiring need to be sized for that load.

Mark

newerwesty1987 wrote: Thanks, but, why not just switch the ground with the switch? The amp load wouldn't be an issue and it would make it more simple.

fxr Sat Aug 24, 2019 8:57 am

crazyvwvanman wrote: Why do you say that the amp load won't be an issue?
The exact same amps flow through the pump ground wire as through the pump power wire. The added switch and ground wiring need to be sized for that load.

Mark

newerwesty1987 wrote: Thanks, but, why not just switch the ground with the switch? The amp load wouldn't be an issue and it would make it more simple.
Just that, indeed. I much prefer using a small switch and thinner wire which are OK for up to 1 or 2A rather than parts rated for 10A. A 10A switch for an inductive load is quite large in comparison to the small slide switch I used.

crazyvwvanman Sat Aug 24, 2019 9:54 am

Yes, adding a relay for this lets you choose from a wider array of switches and switch locations, as well as only needing a single very small wire to do the job on a long wire run.

A typical relay might need roughly a tenth of an amp to activate but can switch 100+ times that much.

Mark

Wildthings Sat Aug 24, 2019 10:22 am

A properly installed time dependent relay will allow a potential thief to start the engine and pull out in traffic and then have the engine die. He is not apt to stick around at this point trying to figure out why the engine suddenly quit on him.

newerwesty1987 Sat Aug 24, 2019 11:13 am

My point was missed. Relay's aren't needed for the small draw of the fuel pump, unless like was said you want to route it far away with tiny wires, but even then, it's probably not needed.

My main point is that you are introducing yet another failure point to an already complex set-up full of relays and old electronics. The last thing I want is another relay to worry about way in the back of my mind.

My kill switch will be the most bluntly simple thing; a simple SPST switch.

KISS!

crazyvwvanman Sat Aug 24, 2019 11:19 am

A relay isn't complicated or failure prone. Most of our 30-40 year old vans still have all or most of the original relays, working fine. Don't use no-name crap from you know where and that goes for the switch you prefer to use as well.

Mark

[email protected] Sat Aug 24, 2019 2:07 pm

crazyvwvanman wrote: A relay isn't complicated or failure prone. Most of our 30-40 year old vans still have all or most of the original relays, working fine. Don't use no-name crap from you know where and that goes for the switch you prefer to use as well.

Mark

Thanks Mark. Just to clarify. You gave me a hard time about this before. For us who know less about electrical things, if one were to use a switch correctly sized for the load to discontinue the circuit for the ground path, that would be fine, correct?

The advantage of using a relay would be that the trigger could be of less amperage, so switch and wireing could be sized accordingly.

We're I am having a conceptual issue is that how big does the switch and wireing need to be for fuel pump? And does it really warrant having a relay. For example wouldn't a fog light switch be sufficient?

crazyvwvanman Sat Aug 24, 2019 2:33 pm

You don't need a relay. As long as the switch is rated for the job by a considerable margin it should be fine. There are lots of small switches that wouldn't be suitable for direct pump power but that would be fine with the relay. Either way, doesn't matter to me. For 87 and later I'd use a relay for sure.

Mark

[email protected] Sat Aug 24, 2019 3:11 pm

Ok thanks, why the difference from 87 on?

crazyvwvanman Sat Aug 24, 2019 3:16 pm

From mid 86 on there is a wiring harness change that I find advantageous for adding the relay. It is a small thing.

Mark



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