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kamzcab86
Samba Moderator
Joined: July 26, 2008
Posts: 7917
Location: Arizona
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 Posted: Tue Oct 01, 2019 11:31 am Post subject: Re: '89 Westy - no start (no power to fuel pump) ~ solved |
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| Vanagon Nut wrote: |
Thanks for posting those pics. Did you see anything obviously wrong with the relay? |
Good thing for the "bump"... missed your question from two weeks ago. 
Nothing was obvious to the naked and magnified eye. Dad used a 9V bolt battery and DVOM to test it and the only conclusion he could come up with was a faulty (not completely dead) diode. There may have been something else in the circuitry that was bad, but can't access that part.
| [email protected] wrote: |
This is fantastic!!!
I just got through testing my 5-pin and it was good, but... looked up the price for replacement. ugh! i found one on rockauto |
Yep... one at Rock Auto and one through NAPA. That's it. You can find a small supply on German eBay, but it'll cost you around $70 + $40 shipping. But then you're still stuck with a stupid 5 pin relay.
Take a preemptive strike and convert to 4-pin... or, at the very least, have the tools on-board to swap to 4-pin if the 5-pin ever fails out on the road.
The parents went to Jerome Jamboree with the van last weekend, and plan to camp at Hualapai Mountain in a week or so... the relay conversion is still going strong! 
You're very welcome! 
_________________
~Kamz 
1986 Cabriolet: www.Cabby-Info.com
 1990 Vanagon Westfalia: Old Blue's Blog
2016 Golf GTI S
"Real knowledge is to know the extent of one's ignorance." - 孔子 |
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Ahwahnee
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Joined: June 05, 2010
Posts: 9799
Location: Mt Lemmon, AZ
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kamzcab86
Samba Moderator
Joined: July 26, 2008
Posts: 7917
Location: Arizona
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| Posted: Tue Oct 01, 2019 2:25 pm Post subject: Re: '89 Westy - no start (no power to fuel pump) ~ solved |
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| Ahwahnee wrote: |
| Is there something special about that relay? |
Yes... it's 40A with an 87a terminal and uses a diode across the coil to prevent damage to the ECU. You could use the relay you linked to, if the pin layout is the same, but you would still want to remove the black/white wire to eliminate the risk of potentially frying the ECU. So, if you're going to do that, might as well convert to a 4-pin setup, which all other year Digifant vans use. 
Here's a better explanation of how it works:
When voltage is removed from terminals 85/86 and the coil is de-energised, the magnetic field that has been created around the coil collapses rapidly. This collapse causes a voltage across the coil in the opposite direction to the voltage that created it (+12V), and since the collapse is so rapid the voltages generated can be in the order of several hundred volts (although very low current).
These high voltages can damage sensitive electronic devices upstream of the +12V coil supply side, such as control modules in alarm systems, and since it's common to take low current alarm output signals to energise relay coils, equipment damage is a real risk.
Using a relay with a diode across the coil can prevent this damage by absorbing the high voltage spikes and dissipating them within the coil/diode circuit (this is known as a blocking or quenching diode). The diode will always be installed in the relay with the stripe on the diode body facing towards terminal 86 (reverse biased) and it is important that +12V is connected this terminal (with 85 connected to ground) or the diode could be damaged.
https://www.12voltplanet.co.uk/relay-guide.html
_________________
~Kamz
1986 Cabriolet: www.Cabby-Info.com
1990 Vanagon Westfalia: Old Blue's Blog
2016 Golf GTI S
"Real knowledge is to know the extent of one's ignorance." - 孔子 |
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Ahwahnee
Samba Member
Joined: June 05, 2010
Posts: 9799
Location: Mt Lemmon, AZ
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| Posted: Tue Oct 01, 2019 2:38 pm Post subject: Re: '89 Westy - no start (no power to fuel pump) ~ solved |
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| Thanks. Every day is an education here. |
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ogelneb
Samba Member
Joined: October 09, 2019
Posts: 37
Location: ON
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| Posted: Mon Aug 17, 2020 11:21 am Post subject: Re: '89 Westy - no start (no power to fuel pump) ~ solved |
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| kamzcab86 wrote: |
I retract my previous posts, in part.  Parents went to drive the van today and no go, even after playing with the wire. Long story short, the problem was not the wire but my previous hunch: Digi power relay. It appears the diode may have gone bad and it was purely luck that we drove across town and back last night without issue. That 40A 5-pin relay is practically NLA, so what to do? 
Converted the relay socket to 4-pin: Moved the black wire terminal from 87a to 86 and removed the black/white wire terminal (capped it off). Installed a 40A 4-pin relay, and voila, problem solved... hopefully, for good (edit: if you are reading this & decide to fo this modification, disconnect the battery first!!). It was started and run a handful of times in the garage tonight without a single issue, including no delay in the pump priming. The two fuel pump wires now have individual continuity too (they did not before). Now, if that relay happens to fail out on the road and they happen to not have a spare, the parents can stop at any FLAPS and get a new relay immediately.
Test drive tomorrow! |
Had to revive this thread...
You’re a life saver, I needed to replace this relay but couldn’t source a replacement for a reasonable price. Your “hack” worked like a charm, used a 53 equivalent from Napa. Cheers, and thanks! |
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kamzcab86
Samba Moderator
Joined: July 26, 2008
Posts: 7917
Location: Arizona
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| Posted: Tue Aug 18, 2020 9:10 am Post subject: Re: '89 Westy - no start (no power to fuel pump) ~ solved |
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| ogelneb wrote: |
Had to revive this thread...
You’re a life saver, I needed to replace this relay but couldn’t source a replacement for a reasonable price. Your “hack” worked like a charm, used a 53 equivalent from Napa. Cheers, and thanks! |
Excellent!
Parents' van has now gone nearly 5,000 7,000 10,000 15,000 20,000 miles since the "hack"... still starting and running like a champ.👍
_________________
~Kamz
1986 Cabriolet: www.Cabby-Info.com
1990 Vanagon Westfalia: Old Blue's Blog
2016 Golf GTI S
"Real knowledge is to know the extent of one's ignorance." - 孔子
Last edited by kamzcab86 on Sun Sep 24, 2023 7:43 pm; edited 3 times in total |
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rubjonny
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Joined: April 12, 2021
Posts: 1
Location: Bracknell, UK
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| Posted: Mon Apr 12, 2021 2:19 am Post subject: Re: '89 Westy - no start (no power to fuel pump) ~ solved |
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Bit of a bump on this one, but I might be able to offer a bit of extra insight on your expensive relays. If these ECU setups are like the MK3 golf, the purpose of this extra white/black wire is to allow the ECU to keep itself switched on for a few seconds after you turn the engine off. If so, you'll notice if you switch the ignition on, off and on again the fuel pump doesn't prime the 2nd time, same as what happens in the MK3 Golf. Leave the ignition off for a few seconds and you'll hear the ECU relay click, then if you turn ignition on again the pump will then prime.
I remember reading about it in some tech manual somewhere, something about issues with warm restarts or bump starts?
The diode inside the relay is there so the ecu ignition live keeping the relay energised doesn't also back-feed the rest of the car ignition circuits, as 87a and 86 terminals would otherwise be linked.
This particular 5 pin relay is also used in the MK2F polo (G40 shape) but even so is still pretty hard to get in europe. If you want to retain this feature you can replace it with a '30' relay from a MK3 Golf, it does mean re-wiring the relay socket to take it but then again you have to rewire the socket to take a standard switched relay anyway. As you already know this feature doesn't really do anything in the real world so no reason to go for a 30 relay over a switched relay tbh.
If you wanted to use the 30 relay the 87a terminal is renamed '86a' and is a smaller 2.8mm terminal. Rest of the terminals numbers/functions are the same but the layout might be different. the 'main 4' terminal layout on a 30 differ to a 53, not sure how it compares to the 5 terminal ones off hand |
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