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mikewire
Samba Member
Joined: March 22, 2010
Posts: 805
Location: San Antonio, TX
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 Posted: Sun Apr 25, 2021 8:50 pm Post subject: Help me understand this odd double relay issue |
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Hey all - I have a strange issue and wondering what to do here. As as primer, my Bus is a 1972 with a 1977 FI 2.0 Type IV swap. So for all intents and purposes of this issue, it's a 1977.
Today I replaced my aging double relay (0 332 514 104) with the newer type (0 332 514 120)
I very carefully transferred all the wires from old to new, replaced a few connectors with better type of terminal and made sure all the terminal numbers matched up with my wiring labels (all wires are labeled because I am missing the connector blocks).
The result was that the Bus would start and run, but the starter would never disengage. I would turn the key on, start it and it would fire up and I could hear the starter still turning. That was not happening with the old relay.
I double and triple checked all my wiring and followed all the wiring diagram and testing/troubleshooting I could find in many of the double relay threads and replies, all looked correct and didn't see anyone else with an issue like this.
Instead of simply putting my old DR back in, I sat and studied the diagrams for a minute and resolved the issue by disconnecting 86a at the relay, which terminates to starter #50. For whatever reason, 86a is still being energized, causing the starter to continuously run.
So my question(s) are - do I need to run 86a -> #50 at all? The Bus starts and runs with no issues. And, can anyone hep me understand why this newer double relay works properly as long as 86a is not connected? The old relay is basically the same as the new, from what I can tell.
I thought the culprit could be the ignition switch but that ignition switch has been replaced, and works just fine. What could I be missing here?
Old double relay:
New double relay:
How it's installed currently, running fine:
_________________
-Mike
@countdowngarage
@bigskyeuro
1972 VW Kombi 9 Passenger Deluxe w/ 2.0L F.I. VWAC swap
1965 VW Beetle Deluxe Bahama Blue |
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aeromech
Samba Member
Joined: January 24, 2006
Posts: 16960
Location: San Diego, California
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| Posted: Sun Apr 25, 2021 9:25 pm Post subject: Re: Help me understand this odd double relay issue |
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Telford Dorr should be along soon. He’ll be able to help you I think
_________________
Lead Mechanic: San Diego Air and Space Museum
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telford dorr
Samba Member
Joined: March 11, 2009
Posts: 3551
Location: San Diego (Encinitas)
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| Posted: Sun Apr 25, 2021 11:17 pm Post subject: Re: Help me understand this odd double relay issue |
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| Quote: |
| So my question(s) are - do I need to run 86a -> #50 at all? The Bus starts and runs with no issues. And, can anyone hep me understand why this newer double relay works properly as long as 86a is not connected? The old relay is basically the same as the new, from what I can tell. |
Without the wire to terminal 86a, you are likely going to have to crank a while on the first start of the day to build up fuel pressure. And you'll definitely need it for cold weather starts, as it runs the cold start jet.
Let's take a look at the schematic (specifically the double relay - yeah, you're gonna have to magnify it a whole lot...):
Notice that terminal 86a feeds starter power to (a) the fuel pump relay, (b) the cold start valve, and (c) the FI controller. Also note that the fuel pump relay is also fed power by a set of contacts in the air flow sensor. This signal passes through a resistor (value unknown) which limits the current flow into this relay coil (purpose unknown). Also, this signal is prevented from backflowing to the starter solenoid by a diode.
Now, assuming you have the relay wired correctly (do re-check it all very carefully: why no nylon connector block on the engine harness? It had one stock, and the self-retaining terminals are available...) then one has to assume a bad relay (missing resistor and diode). I somehow find this unlikely...
Here's a test: get a 1 amp diode (1N4001 or bigger - electronics store on-line) and wire it in series with the wire going to terminal 86a, with the band end of the diode towards the relay. This will stop the double relay from backflowing to the starter. If this works, measure the voltage on terminal 86a with the engine idling. It should be zero. If not, carefully disconnect the wire(s) going to terminal 86. Does the 86a voltage go away? No? Bad relay. Yes? Trace those wire(s) and see where the voltage is coming from. There should be no voltage coming from the FI controller or cold start circuit.
Note that the starter solenoid draws a lot of current (even in 'holding' mode), and I'd hate to thing that was coming from the air flow sensor contacts.
Perchance, do you have a 'cold hard start' relay installed? They take a whole lot less current to operate...
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST)
Last edited by telford dorr on Mon Apr 26, 2021 11:12 am; edited 1 time in total |
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mikewire
Samba Member
Joined: March 22, 2010
Posts: 805
Location: San Antonio, TX
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| Posted: Mon Apr 26, 2021 8:47 am Post subject: Re: Help me understand this odd double relay issue |
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Thank you Telford!!
| telford dorr wrote: |
Without the wire to terminal 86a, you are likely going to have to crank a while on the first start of the day to build up fuel pressure. And you'll definitely need it for cold weather starts, as it runs the cold start jet.
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Makes sense. My Bus has always been a bit cold blooded, and I never have been able to track down the root cause. I wonder if the issue has been persistent the entire time, and the issue wasn't present with the older relay.
| telford dorr wrote: |
Let's take a look at the schematic (specifically the double relay - yeah, you're gonna have to magnify it a whole lot...):
...
Notice that terminal 86a feeds starter power to (a) the fuel pump relay, (b) the cold start valve, and (c) the FI controller. Also note that the fuel pump relay is also fed power by a set of contacts in the air flow sensor. This signal passes through a resistor (value unknown) which limits the current flow into this relay coil (purpose unknown). Also, this signal is prevented from backflowing to the starter solenoid by a diode.
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Agreed - very good call out and exactly why I asked for some expert advice here. Thanks for helping me understand that diagram in a more meaningful way. when doing the 2.0L swap, I ended up having to make my own FI harness on the fuel pump side because it was not included with the rest of the FI parts I bought - where is this resistor located? I may be missing something there. (I see your note about adding the resistor below).
| telford dorr wrote: |
Now, assuming you have the relay wired correctly (do re-check it all very carefully: why no nylon connector block on the engine harness? It had one stock, and the self-retaining terminals are available...) then one has to assume a bad relay (missing resistor and diode). I somehow find this unlikely...
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I need to go back and check all my wires/labels on the FI side of the harness, back to the ECU connector, and verify that those are ID'd correctly. You got me thinking now, and I wonder if I don't have a wire/terminal mislabeled and on the wrong terminal of the DR. I am missing the fuel relay side nylon block - do have the FI nylon block, but removed the connectors from the block to help troubleshoot, and didn't put it back yet. Oh and my double relay is brand new out of the box, so we agree that it's probably not an issue (but ya' never know). I have another new one, just in case.
| telford dorr wrote: |
Here's a test: get a 1 amp diode (1N4001 or bigger - electronics store on-line) and wire it in series with the wire going to terminal 86a, with the band end of the diode towards the relay. This will stop the double relay from backflowing to the starter. If this works, measure the voltage on terminal 86a with the engine idling. It should be zero. If not, carefully disconnect the wire(s) going to terminal 86. Does the 86a voltage go away? No? Bad relay. Yes? Trace those wire(s) and see where the voltage is coming from. There should be no voltage coming from the FI controller or cold start circuit.
Note that the starter solenoid draws a lot of current (even in 'holding' mode), and I'd hate to thing that was coming from the air flow sensor contacts.
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Will do - probably have to order a few from Mouser, I'll get that order in today.
| telford dorr wrote: |
Perchance, do you have a 'cold start' relay installed? They take a whole lot less current to operate... |
Edit: do you mean 'hard start' relay?
I do not, I've read up on them and my assumption was that it's something not needed unless there's issues...I may be there right now lol. Probably makes sense to get one and wire it in.
_________________
-Mike
@countdowngarage
@bigskyeuro
1972 VW Kombi 9 Passenger Deluxe w/ 2.0L F.I. VWAC swap
1965 VW Beetle Deluxe Bahama Blue |
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telford dorr
Samba Member
Joined: March 11, 2009
Posts: 3551
Location: San Diego (Encinitas)
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| Posted: Mon Apr 26, 2021 11:09 am Post subject: Re: Help me understand this odd double relay issue |
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| mikewire wrote: |
| when doing the 2.0L swap, I ended up having to make my own FI harness on the fuel pump side because it was not included with the rest of the FI parts I bought |
I did the same on mine ('75 bug FI onto a '71 bus engine).
| Quote: |
| where is this resistor located? I may be missing something there. |
It's inside and a part of the double relay itself.
| Quote: |
| I need to go back and check all my wires/labels on the FI side of the harness, back to the ECU connector, and verify that those are ID'd correctly. You got me thinking now, and I wonder if I don't have a wire/terminal mislabeled and on the wrong terminal of the DR. |
Good idea!
| Quote: |
| I am missing the fuel relay side nylon block - do have the FI nylon block, but removed the connectors from the block to help troubleshoot, and didn't put it back yet. |
When I built my new engine FI harness, I sourced a used connector housing for the body side harness from a junkyard. Makes it much more serviceable. German Supply in Canada sells new ones.
Diodes:
| Quote: |
| Will do - probably have to order a few from Mouser, I'll get that order in today. |
FYI: the latching connector pins are available from DigiKey.
| Quote: |
Edit: do you mean 'hard start' relay?
I do not, I've read up on them and my assumption was that it's something not needed unless there's issues...I may be there right now lol. Probably makes sense to get one and wire it in. |
Uh, yeah - hard start relay. The only reason I mentioned it is because it draws so little current (compared to the starter solenoid) is that it wouldn't take much backfed current to hold it closed.
If your bus starts fine without one, don't sweat it. It means that your electrical system is in good shape. [Now that said, it will remove the starter solenoid load from the ignition switch, which will extend the switch life significantly...]
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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mikewire
Samba Member
Joined: March 22, 2010
Posts: 805
Location: San Antonio, TX
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| Posted: Fri May 07, 2021 8:54 am Post subject: Re: Help me understand this odd double relay issue |
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Thanks Telford for all your advise. I found the issue, and it must have been self-inflicted lol.
All the information is out there, I just had to compile it just a bit (see below), but after tracking back all the harness connectors to the proper ECU and components, I must have had the connectors on the FI harness relay side connected incorrectly.
After a methodical test and verification procedure, I inserted the locking pins into the single connector block, and it fired right up with no issues. All seems good now!
| Code: |
Bus Double Relay -> ECU pins
Fuel pump side:
85 - 2.8mm -> Ground
86a - 2.8mm -> Starter #50 (12v cranking)
86c - 2.8mm -> Coil + #15 (12v key on)
88d - 3.5mm -> Fuel pump (12v cranking or key on, AFM flap open)
88y - 3.5mm -> Battery + (12v always)
88z - 3.5mm -> Battery + (12v always)
FI harness side:
86 - 2.8mm -> Thermo time switch, (12v cranking) -> ECU pin #4
86b - 2.8mm -> AFM #36 (12v key on) -> and ECU #20 ('76-'79 only)
88a - 3.5mm -> AFM #39 (12v key on)
88b - 3.5mm -> Resistors (12v key on) -> and ECU #10
88c - 3.5mm -> AAR (key on AFM, flap open) |
After looking into the issue with the double relay, I noticed the resistor pack looked a bit sad, so after inspecting it I found one of the wires had broken off - so there's no way I was running on 4 cylinders. Anyway I ended up using a butt connector as temp fix, and all was decent, but ended up buying a used resistor pack.
The cause of the broken wire seemed to be caused by wire strain on the 5 wires coming from the resistor pack, so I set out to solve that problem. I figured I could 3D print a bracket that would hold the connector on the resistor pack and help relive the wire strain.
Here's a before the bracket, and after below bracket after:
The bracket is a little bit of a prototype, and I used an o-ring to help support and hold the entire connector to the bracket.
Hopefully it will help keep the resistor pack wires high and tight (or not so tight) 
Again, huge thanks to Telford!!!
_________________
-Mike
@countdowngarage
@bigskyeuro
1972 VW Kombi 9 Passenger Deluxe w/ 2.0L F.I. VWAC swap
1965 VW Beetle Deluxe Bahama Blue |
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secretsubmariner
Champagne Wrangler
Joined: January 08, 2011
Posts: 3104
Location: Tulsa, OK
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| Posted: Fri May 07, 2021 1:00 pm Post subject: Re: Help me understand this odd double relay issue |
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Nice bracket! Robbie and I found a snapped wire on the resistor pack, too. Cylinder 3 or 4 wasn't firing at all because of that. Swapped in a spare, and the engine pulled like I've never felt before. Way cool.
Congrats, and happy cruisin'!
_________________
-Tony
ᏣᎳᎩᎯ ᎠᏰᎵ
1978 Champagne Edition Bus FI
1970 Auto Fastback FI |
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telford dorr
Samba Member
Joined: March 11, 2009
Posts: 3551
Location: San Diego (Encinitas)
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| Posted: Fri May 07, 2021 11:58 pm Post subject: Re: Help me understand this odd double relay issue |
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Very nice solution to a common problem.
You should sell those on theSamba...
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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mikewire
Samba Member
Joined: March 22, 2010
Posts: 805
Location: San Antonio, TX
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| Posted: Sun May 09, 2021 9:12 pm Post subject: Re: Help me understand this odd double relay issue |
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| secretsubmariner wrote: |
Nice bracket! Robbie and I found a snapped wire on the resistor pack, too. Cylinder 3 or 4 wasn't firing at all because of that. Swapped in a spare, and the engine pulled like I've never felt before. Way cool.
Congrats, and happy cruisin'! |
| telford dorr wrote: |
Very nice solution to a common problem.
You should sell those on theSamba... |
Thanks! Yep I was surprised to find that little gem was broken and #3 not firing, so bonus that now I get all 4 cylinders and my CHT is reading properly lol. Sometimes it's those types of things that are common sense and in hindsight all I can say to myself is "duhhhh" 
I'll run this bracket in test mode for a bit - it's my own design and it's made from PLA, which is not very heat resistant, so once I know it's going to be the final version I may sell it if there's some demand...send me a PM if interested in testing one. An ABS version would be better, that material will probably tolerate the engine bay heat better in the long term.
_________________
-Mike
@countdowngarage
@bigskyeuro
1972 VW Kombi 9 Passenger Deluxe w/ 2.0L F.I. VWAC swap
1965 VW Beetle Deluxe Bahama Blue |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12721
Location: on a bike ride somewhere
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| Posted: Sun May 09, 2021 11:25 pm Post subject: Re: Help me understand this odd double relay issue |
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I'd be in for a few if you could get them out of ABS!
Robbie
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Learn how your vintage VW works. And why it doesn't!
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mikewire
Samba Member
Joined: March 22, 2010
Posts: 805
Location: San Antonio, TX
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| Posted: Fri May 14, 2021 1:56 pm Post subject: Re: Help me understand this odd double relay issue |
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| airschooled wrote: |
I'd be in for a few if you could get them out of ABS!
Robbie |
Not quite setup yet for ABS, but I'd print a couple up in PLA if you want to test them out. Need to get an enclosure for my printer and a spool of filament, then I should be setup. I could always send off the .STL to a 3rd party to print as well, but it would cost some.
Robbie, you probably could answer this question easily - the glass transition temperature for PLA is around 140F...it may warp, but not melt. How hot does the rear engine bay/firewall area get?
Maybe PLA would suffice for all intents a purposes of this part.
_________________
-Mike
@countdowngarage
@bigskyeuro
1972 VW Kombi 9 Passenger Deluxe w/ 2.0L F.I. VWAC swap
1965 VW Beetle Deluxe Bahama Blue |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12721
Location: on a bike ride somewhere
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| Posted: Fri May 14, 2021 2:29 pm Post subject: Re: Help me understand this odd double relay issue |
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I would PLA for a mock-up but wait until ABS is available to sell/ship them out.
The compartment doesn’t get much hotter than ambient while running, especially at high speeds, but after shutdown it could get past 140*f if you’re tuned properly. You may be able to gusset the design to resist warping, but I dropped FEA and took music theory instead...
Even virgin ABS blends can deform under stress at that temp, but I doubt the compartment gets much hotter. I bet Colin has actual temp readings.
Robbie
_________________
Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com |
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mikewire
Samba Member
Joined: March 22, 2010
Posts: 805
Location: San Antonio, TX
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| Posted: Sat May 15, 2021 8:50 am Post subject: Re: Help me understand this odd double relay issue |
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| airschooled wrote: |
I would PLA for a mock-up but wait until ABS is available to sell/ship them out.
The compartment doesn’t get much hotter than ambient while running, especially at high speeds, but after shutdown it could get past 140*f if you’re tuned properly. You may be able to gusset the design to resist warping, but I dropped FEA and took music theory instead...
Even virgin ABS blends can deform under stress at that temp, but I doubt the compartment gets much hotter. I bet Colin has actual temp readings.
Robbie |
Thanks Robbie - that is all great info, and much appreciated feedback. That pushed me over the edge...I bought some ABS filament and I'll work on building an enclosure for my printer this week. First successful print has your name on it.
There's one tweak I want to make on the retaining tabs for the o-ring and I think the overall design is good to go. My initial testing it seems to be holding everything and supporting the connector and wires just fine, although it's been limited since my distributor is not well (too much vertical play...getting a restored 205S from Bill).
I have a couple of other parts I've been wanting to print with ABS I just haven't changed course to use a different setup. This gives a good reason to try something new with my printer
_________________
-Mike
@countdowngarage
@bigskyeuro
1972 VW Kombi 9 Passenger Deluxe w/ 2.0L F.I. VWAC swap
1965 VW Beetle Deluxe Bahama Blue |
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