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borninabus
Samba R&D Dept.
Joined: May 18, 2006
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Location: Arizona Highways
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 Posted: Fri Jan 05, 2018 8:47 am Post subject: Re: Electrical Meltdown! What Happened? |
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| Vanagon Nut wrote: |
| Assuming the PS wire was causing the short, I have to wonder why that PS wire didn't fail first? |
think about how a welder works.
the hottest place is where the ground is.
left to it’s own devices, that wire was next.
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crazyvwvanman
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| Posted: Fri Jan 05, 2018 10:26 am Post subject: Re: Electrical Meltdown! What Happened? |
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I have the same concern. The PS wire is a smaller gauge than the wire that badly fried. If that PS wire was the cause, I'd expect obvious signs of heat on that PS wire also. I've seen such damage several times.
There are 2 wires to the PS switch. Only 1 of them is the unfused power wire. If the other wire came loose and contacted bare metal it would do no harm. I wonder which wire is shown in the photo laying on the metal intake runner? What color is it and what year van?
One partial explanation for how the larger main power feed is fried while the smaller PS wire isn't fried is that the main power wire carries all of the current for the injection system and fuel pump so if the PS wire shorts to metal that short circuit current is added to the existing normal current in the power feed wire. So the melted wire would have to carry a bigger load during the short than the shorted PS wire would. I doubt that fully explains why the PS wire looks ok though.
I would do more investigation of the full FI harness.
Mark
| Vanagon Nut wrote: |
Assuming the PS wire was causing the short, I have to wonder why that PS wire didn't fail first?
Neil. |
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djkeev
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eeebee
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| Posted: Fri Jan 05, 2018 11:32 am Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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https://www.thesamba.com/vw/forum/viewtopic.php?t=610628
My harness fried too. I am pretty sure that it was the flag connectors at the power steering switch. I believe that these connectors had covers to prevent grounding. Leaving them bare is a risk.
The power steering wire disintegrated back to the idle control module and melted the wiring in the fuel injection harness. The harness was a real mess.
I sourced a used harness which is handy because I now have a bunch of extra connectors and have used some to make test leads and stuff.
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1987 Vanagon Wolfsburg Special Edition
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crazyvwvanman
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| Posted: Fri Jan 05, 2018 11:45 am Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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Early Digifant harnesses had the PS switch power wire daisy-chained from the idle control module socket power wire but later years did not. So the version of harness makes a difference as to where and how much damage is likely.
Mark |
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borninabus
Samba R&D Dept.
Joined: May 18, 2006
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| Posted: Fri Jan 05, 2018 11:53 am Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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continued thanks 
its an 86 van (3/86 on the door sticker) and i have a complete replacement FI harness.
the wire laying on the intake is from the right side (as you look at the switch).
had to source the fuel pump harness of an 85 van which is a bit different and took some time. some cut & paste and a couple new wires will have to happen.
gonna have to put it down for the day, but i’ll check in here from time to time.
resume repairs tomorrow.
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crazyvwvanman
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| Posted: Fri Jan 05, 2018 12:06 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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Yes, up to mid 86 there was only a 1 pin fuel pump wire in the engine FI harness and the pump had a separate ground wire to a point on the body near the fuel pump. From mid 86 on the FI harness got a 2 pin connector for the fuel pump and the fuel pump ground wiring point got moved to the engine compartment grounding bolt with other ground wires.
edit: if you are switching to a different 86 version harness you may have a little bit of head scratching to do regarding the black wire connection.
Mark
Last edited by crazyvwvanman on Fri Jan 05, 2018 1:25 pm; edited 1 time in total |
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Merian
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| Posted: Fri Jan 05, 2018 12:53 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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| crazyvwvanman wrote: |
Early Digifant harnesses had the PS switch power wire daisy-chained from the idle control module socket power wire but later years did not. So the version of harness makes a difference as to where and how much damage is likely.
Mark |
do you know which VIN has what?
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djkeev
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crazyvwvanman
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| Posted: Fri Jan 05, 2018 1:40 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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The PS switch power wire shorting to metal can cook all versions of the Digifant harness, just differently on different versions.
This particular wiring change happened after 87 vans. The most obvious way to see which way a given harness is done is looking closely at the wires to the idle control unit behind the pass side tail light. If there is a black and 7 whites it has a shared power wire from there to the PS switch. You can see that there is a white wire crimped into the same socket pin as the black wire. Black is power into the idle control unit and the paired white is power out to the PS switch wire. Later versions don't have 2 wires paired on that socket pin and have fewer white wires. On those later ones the PS switch power comes from elsewhere inside the harness, still un-fused.
I have seen at least 5 versions of the Digifant harness and I wouldn't much trust any given van to still have the one it came with anymore. I'm sure most do.
Mark
| Merian wrote: |
| crazyvwvanman wrote: |
Early Digifant harnesses had the PS switch power wire daisy-chained from the idle control module socket power wire but later years did not. So the version of harness makes a difference as to where and how much damage is likely.
Mark |
do you know which VIN has what? |
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dhaavers
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| Posted: Fri Jan 05, 2018 4:20 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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(re:...flag connectors at the power steering switch... )
| eeebee wrote: |
| ...I believe that these (^^^) connectors had covers to prevent grounding... |
According to Kam, the insulated connectors only showed up towards the end of the 1990 model year... 
| kamzcab86 wrote: |
| dhaavers wrote: |
| What year do you suppose the protector showed up? |
All I can tell you is that the parts catalog shows 2 in use for the MV (part #211971921) up through VIN L-045388. The peculiar part is, #045388 has a production date of December 31, 1989. Mine was built in February 1990 and has just one (certainly plausible one went missing over the years).
Brickwerks sells a retrofit: https://www.brickwerks.co.uk/wiring-connector-6-3mm-flag-white.html .
From L-045389, the vans allegedly came with a fuel injector-type connector (#357972752), which mine certainly does not have. 
Moral of the story: Who the hell knows...  |
Indeed. 
- Dave
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dhaavers
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| Posted: Fri Jan 05, 2018 4:29 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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| crazyvwvanman wrote: |
...I have seen at least 5 versions of the Digifant harness and I wouldn't
much trust any given van to still have the one it came with anymore... |
Exactly why I chose to rebuild my original harness rather than deal with a potentially wonky mismatch.
As noted, there are two different wiring diagrams and fuse listings just within the 86 model year...
- Dave
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kamzcab86
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Joined: July 26, 2008
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| Posted: Fri Jan 05, 2018 5:31 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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| dhaavers wrote: |
| According to Kam, the insulated connectors only showed up towards the end of the 1990 model year... |
No, no... they were in use up through VIN L-045388 according to the catalog. That means: Who knows when they first appeared, but they ended with 1990 #045388 (which is incorrect, since my '90 is in the 056000 range and has at least one). 
And this thread reminded me that I still haven't heat-shrunk the one naked connector on mine.  Tomorrow's to-do project along with adding that fuse!
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1986 Cabriolet: www.Cabby-Info.com
 1990 Vanagon Westfalia: Old Blue's Blog
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"Real knowledge is to know the extent of one's ignorance." - 孔子 |
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borninabus
Samba R&D Dept.
Joined: May 18, 2006
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| Posted: Fri Jan 05, 2018 6:38 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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i am aware of the different 86 wiring harneses. fortunately, the one i have is an exact match kinda pissed that i sold off my late model harness with the crankcase vent heater provision and color coded wiring. best of all, the replacement harness i have has both insulators on the power steering switch terminals 
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Aryana
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| Posted: Fri Jan 05, 2018 7:53 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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To double check before I install this, will retrofitting a 10A fuse inline on the red wire below protect the power steering pressure switch from melting down my harness as well as the other fuel injection circuits?
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dhaavers
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| Posted: Fri Jan 05, 2018 8:12 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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^^^ YES...Perfect!
- Dave
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dhaavers
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| Posted: Fri Jan 05, 2018 8:48 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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| kamzcab86 wrote: |
| dhaavers wrote: |
| According to Kam, the insulated connectors only showed up towards the end of the 1990 model year... |
No, no... they were in use up through VIN L-045388 according to the catalog. That means: Who knows when they first appeared, but they ended with 1990 #045388 (which is incorrect, since my '90 is in the 056000 range and has at least one). |
Sorry...misunderstood. 
All I know for sure is my late 86 (build date Jan '86) had NOTHING on either connector...
~~~~~
On another note...
FWIW: My (late 86) harness was burned the WHOLE length of the black wire from the (26) connector (inside
the harness left side of the engine bay) to within 12" of the ICU (@ right side tail light) and then from that
point back to within 3" of the PS switch (center) & of course seems to jibe with Mark's description:
| crazyvwvanman wrote: |
| Early Digifant harnesses had the PS switch power wire daisy-chained from the idle control module socket power wire but later years did not. So the version of harness makes a difference as to where and how much damage is likely... |
And...
| crazyvwvanman wrote: |
[On 86-87 vans]...the idle control unit behind the pass side tail light...there is a black and 7 whites...has a shared power wire from there to the PS switch...there is a white wire crimped into the same socket pin as the black wire. Black is power into the idle control unit and the paired white is power out to the PS switch wire...
[after 87 vans]...don't have 2 wires paired on that socket pin and have fewer white wires. On those later ones the PS switch power comes from elsewhere inside the harness, still un-fused... |
I didn't see in OP's post, but I assume from this ^^^ information and from the completely
different nature of his burned harness that he has a later (post-87) van...??? Seems logical, yes?
Inquiring minds...
- Dave
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Aryana
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| Posted: Fri Jan 05, 2018 9:29 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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| Thank you for the confirmation Dave! |
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?Waldo?
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| Posted: Fri Jan 05, 2018 9:39 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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| Is the power steering switch unfused on the 1.9 Digijet? Is the same fuse location recommended? |
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dhaavers
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| Posted: Fri Jan 05, 2018 11:08 pm Post subject: Re: ATTN: Check Your Power Steering Switch Wiring!!! |
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Not an expert on the 1.9, but I did spend some time scanning Bentley and didn't see
any fuse in the FI circuit...no sign of a PS pressure switch, either...
Anyone...???
- Dave
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