Help - 97 1Z buzzing 109 relay

Fixed - 97 1Z buzzing 109 relay

Hey guys,

***FIXED*** - Ended up being the nut on the mounting plate for the ECU which was lose. For those that don't know (like I didn't) that's also where your ECU goes to ground

Summary:
Friday night - wife goes to start car after 6hr work shift, glow plug light doesn't come on and buzzing from dash. Car cranks but no fire. Starts immediately when jumped. Drives car home and same thing
I come home and isolate sound to said relay. Pulled off housing and basically changed the shape of a braided wire to push onto gate and keep it from opening as the buzzing sounds was a result.of gate trying to close but failing. Leave overnight.
Car works for drive to work, drive after work, drive to and from Edmonton (to Pick N Pull for new relays) on Sunday, about 120kms on Monday, sits all day Tuesday
Car is completely and utterly dead Tues morning. No lights left on only possibly the rear defrost but that has never previously caused issues (seems to shut off fine when car is turned off)
Tried swapping power relays as I figured the closed gate is causing constant draw.
New relay now buzzes and original problem is back
Alt is putting out 13.8V, batt at rest is 12.4, I'm getting 12V to 30 on the relay and with the buzzing one in I get 3V to 87 (slot 6) and 10.5V to 85 (slot 5)
With modded relay, I get 3V to 85 (slot 5), 13V to 87 bottom (Slot 6) and no V on 87 top (Slot 1) but car runs and provides 13V to 30
If I turn the fan and defrost on then 87 top (Slot 1) goes to -1.5V and the 87 bottom (Slot 6) and 30 drop to 11.3V
Possibly unrelated but with rear defrost on there is a noticeable loss of power

the black 109 relays are defective from the factory, buy a new gray 109

What is battery voltage when cranking?

Check your pin numbers, I think that you have them mixed up.

And check your grounds.

@lowrider - the "modded" relay is already one of the grey ones

@whitedog - battery passed all tests with voltage only.dropping to 11 when cranking and yes, i got 85 and 87 mixed up with the modded relay. Will edit

K retested and I'll edit original post

Alt is putting out 13.8V, batt at rest is 12.4, I'm getting 12V to 30 on the relay and with the buzzing one in I get 3V to 87 (slot 6) and 10.5V to 85 (slot 5)

With modded relay, I get 3V to 85 (slot 5), 13V to 87 bottom (Slot 6) and no V on 87 top (Slot 1) but car runs.

If I turn the fan and defrost on then 87 top (Slot 1) goes to -1.5V and the 87 bottom (Slot 6) and 30 drop to 11.3V

Those should be 87 and 87A. 87A should be the one in the center of it all and that would be the normally closed circuit. 87 would be the normally open circuit and is the one that would be sending power to the ECU.

30 is from battery 86 is ground and 85 is the signal wire. You are only getting 3 volts to power the windings for the solenoid in the relay. You need to find out why you are only getting 3 volts. I don't know these MkIII cars very well, but someone has mentioned the key switch. I think it was in the relay 109 thread.

Whitedog, Thank you. You busted this open for me

I was assuming that the 30 (Slot 4) was supplying the power to close the relay which then passed it through to 87 (Slot 6) so, thinking that, I assumed that the relay switch was getting power.

I think my older relay is different from what you're talking about but same basics (and I also found a wiring diagram which is much nicer than what's printed on the relay)

So, like Whitedog said, 85 is just a signal wire to allow power from the ignition through Slot 1 (86), what I was calling "87 top", to go through the coil and pull the switch closed, allowing power from 30 (Slot 4) to go to 87 (Slot 6) or what I was calling "87 Bottom"

So with that in mind, going after the ignition switch since, as my tests show, I'm getting no voltage to 86 (Slot 1) when cycling the key.

Thoughts? Am I going the right direction? Or just sounding like an idiot?

Just to be clear:

85- signal in to winding

86- winding ground

30- power in

87a- normally closed output

87- normally open output.

Nope, now you've lost me

From the diagram I'm seeing (I don't know how to post pics from my phone) it looks like this (I only have 4 pins/slots)

86 (Slot 1) - Pwr from IGN to winding
85 (Slot 5) - winding ground

That closes the switch for power to go from

30 (Slot 4) - power in
To
87 (Slot 6) - power to ecu

Found this as the closest thing except I have no 87a pin as mine is only a 4 pin

OK 85&86 can be swapped since its just a solenoid and there are no resistors or diodes in there. And don't worry about not having the 87a pin since that's for a generic relay. Otherwise you have it right.

Either way, I'm not getting power to the coil to close it up when, previously, I thought I was

Ignition switch then?

Out of curiosity...how much voltage should be going into that coil to close the switch?

It should be battery voltage as far as I know.

The 109 relay is a bit different from the normal relay in that it has 30 and 86 connected together internally. It has 4 pins, but only 3 of them are active, the extra being used to make it fit in only the right socket.

Terminal 30/86 is connected to battery power, 87 is switched output to the ECU and 85 connects to the ECU. When the ECU gets power from the ignition switch, it grounds the relay terminal 85. This completes the circuit for the coil, and the relay pulls in supplying power to the ECU. It is a bit of a long way around to get there, or maybe it is an engineer's shortcut.

I would be more suspicious of the ECU grounding as being the cause of the buzzing relay than the + supply side.

So you're saying I shouldn't ever have voltage at Slot 1?

Mitchell wiring diagram 97 Passat TDI

This is the diagram I've recently been going off of. Please let me know if the link doesn't work

Thank you Alchemist for further clarifying how this relay works which helped me confirm that I WAS getting power to the relay.

**FIXED*** - Ended up being the nut on the mounting plate for the ECU which was lose. For those that don't know (like I didn't) that's also where your ECU goes to ground

It sounds like you were getting power, but not the signal. For grins, can you do the same voltage check again and see what you have now?

Buehler said:

Thank you Alchemist for further clarifying how this relay works which helped me confirm that I WAS getting power to the relay.

**FIXED*** - Ended up being the nut on the mounting plate for the ECU which was lose. For those that don't know (like I didn't) that's also where your ECU goes to ground

Click to expand...

Something is not quite right here. The ECU ground is through 3 Brown wires on Pins 1, 24, and 46. There is an internal connection to the case, so if that is how your ECU is grounding the wires are not connected to ground. It would be a good idea to follow the harness to find out what happened to those ground wires.

Damn

No chance those just complete the ground as they'd assume you'd also have your ECU bolted in?

Are you able to tell if all 3 of those grounds go to the circle by the fuse panel?

And, sorry, but just clarifying:

"There is an internal connection to the case"

Do you mean there must be one since I am grounding that way but there isn't supposed to be

Or you're confirming that there is one that is supposed to be there

The three wires are spliced together in the harness and come out as one wire. This is done to allow enough capacity for the current the ECU handles.

The internal ground connection is just the mounting screws for the circuit board touching the ground foil on the board and going into the case. It was never intended to carry any load current.

You have gotten away with it so far, but I would expect bad things to happen inside the ECU if left this way.

Where does the splice occur as I'm having trouble finding the ground wire off the loom once it comes through the firewall. Wouldn't I be having issues with the MAF as well as it looks like it shares the same ground?