[T3] Fuel Pump Relay - 69 Fastback
willjahn975 at gmail.com
Sun Jul 11 17:02:21 PDT 2021
I've never worked on or saw a 69 . They are similar yet different from my
73 . Still there is one wire from the pump relay to the ECU that supplies
the ground 85 on the pump relay. the Bentley does not show the 69 pump
relay yet the other end of that wire on a 73 is in the engine compartment
left side . I assume that connector would be near where the main harness
enters through a grommet on the left side it will be a single connector in
a plastic cover; by now they are not clear see through any more. It's
possible that the connector which is inside a by now no longer clear
plastic cover is a 1/4" male and female spade connector is corroded and not
making good contact which seems odd because you did say I worked a few
times. Yes it's possible . I may also be the ECU and those are year
Try grounding the disconnected 85 on the pump relay , just make sure it is
disconnected , if it',s not you can kill the ECU.
Jim knows more about the earlier models than most also Tram on Samba knows
On Sun, 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
> " 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>
>> 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>
>> > 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
>> > ign switch might be the problem. It seems intermittent to me and they
>> > 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.
>> > It's just a thought and after what he has already checked and really
>> > nothing it might be a good place to check . Never tried to bypass the
>> > 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
>> > the battery hot to the run just to see if the pump and relays have
>> > voltage could even unplug the coil during the test so it will not
>> >> 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
>> >> 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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