[T3] Fuel Pump Relay - 69 Fastback

William Jahn willjahn975 at gmail.com
Sun Jul 11 17:17:01 PDT 2021


If the pump relay works then you need to find out what the issue is ,
either it's the wire or the ECU has an internal issue . The other end of
that wire to the ECU  should exit the large grommet on the left where all
the wires enter the engine and tail lights and so on . It will be a single
plastic cover with a male and female 1/4" spade connector inside . It could
be corroded .  Just do not leave the wire connected and ground it however
you do it. If you just ground it connected you will kill the ECU.

On Sun, Jul 11, 2021 at 5:07 PM William Jahn <willjahn975 at gmail.com> wrote:

> Take the pump relay connector off and remove 85 from the connector . Then
> ground the relay pin . DO NOT ground the wire , if you do it will kill the
> ECU . If you want you can cut the wire don't let the end running to the ECU
> touch any ground . strip that wire at the pump relay end and use a jumper
> to ground it .
>
> On Sun, Jul 11, 2021 at 5:02 PM Tim Schiller <schillertim at comcast.net>
> wrote:
>
>> Ground the wire or the pin? I assume the pin
>>
>> Sent from my iPhone
>>
>> > On Jul 11, 2021, at 4:28 PM, William Jahn <willjahn975 at gmail.com>
>> wrote:
>> >
>> > you can take the pump wire off the pump relay to rule out the pump
>> being
>> > the problem , it won't hurt anything. I wouldn' ground the ECU wire.
>> Keep
>> > in mind the reason there is a fuse for the pump is in case either the
>> pump
>> > or the wiring from the pump relay to the pump shorts.
>> >
>> > I doubt you have faulty relays since you changed both and it made no
>> > difference.
>> >
>> > " I was reading out of a Clymer manual and it discussed pulling the wire
>> > from the 85 pin on the pump relay that I believe goes to the ECU #19. It
>> > says to ground this wire to Bypass ignition. Says the pump should run
>> full
>> > time when doing this to test if pump is good " That does not bypass the
>> > ignition it just grounds the pump relay coil that pulls the contacts
>> closed
>> > to send power to the pump though the pump relay contacts. 30 and 87.
>> >
>> > When you turn the key, what does it feel like? Is it stiff , does it
>> > return back when you release the key?
>> >
>> > The reason I ask is because the ign switch the electrical part when you
>> > start the car it powers the starter and supplies power to the fuse box
>> and
>> > relays , when you release the key it just powers the electrical to run
>> the
>> > coil and ECU and headlights and so on. Once you release the key all that
>> > does is remove power to the starter.
>> >
>> > All I'm getting is it did work a few times and will not most of the
>> time.
>> >
>> > The pump relay 30/51 battery voltage great. 86 fine. 85 is the ground
>> from
>> > the ECU both 86 and 85 are the relay coil 30 and 87 are the contacts. So
>> > the power relay is doing it's job or you would not have 13 volts on 30
>> on
>> > the pump relay. You can ground 85 as long as you remove it from the pump
>> > relay and use another ground like a jumper . I never checked if 85 had
>> > voltage on it because it's a ground and I don't feel it's a good idea to
>> > check for voltage there and I don't know how much resistance the coil
>> has ,
>> > it may read battery voltage I just never did that. To not have voltage
>> on
>> > 87 tells me the ground 85 is not grounding via the ECU so the coil is
>> not
>> > closing the contact to send voltage from 30 to 87. Try removing 85 from
>> the
>> > pump relay and ground it. If that works then either ECU is not working
>> that
>> > ground circuit or there is an issue with that wire from the pump relay
>> to
>> > the ECU. The mystery is why it did work a few times.
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > '
>> >
>> >> On Sun, Jul 11, 2021 at 3:03 PM Tim Schiller <schillertim at comcast.net>
>> >> wrote:
>> >>
>> >> Without putting a bigger charger on battery, it is at 13V now. There is
>> >> also 13V at the power relay.
>> >>
>> >> Thought I would start at beginning at check pump relay again. There is
>> 13V
>> >> at the 30 pin. When ignition is turned on, there is also 13V at the 85
>> and
>> >> 86 pins.
>> >>
>> >> When I check the 87 pins it is pretty consistent at zero. This is true
>> >> with multiple new relays. If I disconnect pump wire, should I get 13V
>> at
>> >> the pin? I was just trying to eliminate the pump causing a short.
>> >>
>> >> The negative braided battery cable has some corrosion. I will need to
>> >> order one if I’m to replace.
>> >>
>> >> Harbor Freight has an ignition bypass to allow starting of car when you
>> >> can’t fully turn key. Is this the type of bypass you are referring to?
>> >>
>> >> I was reading out of a Clymer manual and it discussed pulling the wire
>> >> from the 85 pin on the pump relay that I believe goes to the ECU #19.
>> It
>> >> says to ground this wire to Bypass ignition. Says the pump should run
>> full
>> >> time when doing this to test if pump is good. Didn’t want to do until
>> >> asking someone much smarter than I.
>> >>
>> >> I still need to check the ground from the frame to the transmission. I
>> >> also need to follow the wire from the starter as suggested. How do you
>> >> follow a wire when it disappears inside the harness and is covered
>> with the
>> >> rest of the wires?
>> >>
>> >> It seems like the biggest problem is the is no power at the 87 pin on
>> pump
>> >> relay.
>> >>
>> >> Sent from my iPhone
>> >>
>> >>>> On Jul 11, 2021, at 2:03 PM, William Jahn <willjahn975 at gmail.com>
>> wrote:
>> >>>
>> >>> When I checked mine a while back I unplugged the ign coil . Since
>> this
>> >>> issue seems to work sometimes and it runs wouldn't it make sense that
>> the
>> >>> ign switch might be the problem. It seems intermittent to me and they
>> >> don't
>> >>> last forever and it's a moving part.  We know it's not the relays he
>> >>> replaced both with the same result. Seems  since the ign switch could
>> be
>> >>> the cause. I don't know if 69 has a replacement part.
>> >>>
>> >>
>> https://www.westcoastmetric.com/c-1182978-vw-type-3-1969-vw-type-3-electrical-ignition-switches-harness.html
>> >>>
>> >>> It's just a thought and after what he has already checked and really
>> >> found
>> >>> nothing it might be a good place to check . Never tried to bypass the
>> ign
>> >>> it's possible to do as long as one can use a jumper to pull from the
>> >>> starter circuit once it starts . Or for the sake of just a test just
>> jump
>> >>> the battery hot to the run just to see if the pump and relays have
>> >> battery
>> >>> voltage could even unplug the coil during the test so it will not
>> >> overheat.
>> >>>
>> >>>> On Sun, Jul 11, 2021 at 1:34 PM Jim Adney <jadney at vwtype3.org>
>> wrote:
>> >>>>
>> >>>>> On 11 Jul 2021 at 11:21, William Jahn wrote:
>> >>>>>
>> >>>>> When checking for a voltage drop in one wire to the power relay one
>> the
>> >>>> pump
>> >>>>> relay times out the only draw on the power relay is the ECU .
>> >>>>
>> >>>> Also, the ignition
>> >>>> --
>> >>>> *******************************
>> >>>> Jim Adney, jadney at vwtype3.org
>> >>>> Madison, Wisconsin, USA
>> >>>> *******************************
>> >>>>
>> >>>> _______________________________________________
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