Relay 109 - Main Power Supply Fuse

torquey

Member
Joined
Jan 6, 2001
Location
Montreal
My car's engine died a few times lately... no check engine lights.... no RPMs.... changed relay 109 with the new grey one and all is fine now !
Thanks to this thread.
 

Romi

Veteran Member
Joined
Jun 21, 2002
Location
NM
Time to resurrect an old post...I'm thinking we might have a 109 issue on our 2002 Jetta automatic. We drove it around town running errands then parked it to go into a restaurant to eat dinner. When we came out the car wouldn't start, it would crank over with plenty of power and the glow plug light would come on and work as normal. The car just wouldn't start. After sitting around checking fuses for a half hour, I decided to disconnect the battery to "reset" the computer. Car didn't start the first time, but on the 2nd try it fired up and ran fine
. Over the last 2 days it has started and run fine. I haven't had a chance to check the relay color yet but could this be a relay 109 issue?
 

dieselron

Active member
Joined
Oct 12, 2004
I am having trouble with my 2000 Golf TDI dying out now and then, and will turn over but not start unless you wait awile. The engine malfunction light then comes on and the following codes are stored; VAG 17109 SAE P0725; VAG 18265 SAE P1857; VAG 18258 SAE P1850. Could this be a 109 relay problem? I have an appointment for dealer service but would like some experienced opinions to know what to expect.
 

bennyvatten

Member
Joined
Mar 25, 2005
TDI
Audi 80 Avant 1,9tdi
Does a bad 109 cause fault codes? My car has a problem on highways. For like a split second it seems that it stalls, but then it doesn't. It's almost like it lost all power for about a second. It might do this couple of times in a row, but than run fine for hundreds of miles. A bad 109 relay? It had a fault code which I don't precisely remember but I interpreted it as the ECU loosing electrical supply intermittently...
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
Yes, it can do that. You also dropped out of cruise (if it was set). Replace it before it goes all the way out and leaves you stranded.
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
I haven't heard of this being a problem with 2003 or thereabouts forward. However, the description of the problem is quite consistant with a 109 going out. It might be something else (bad grounds, etc) but odds are....

Also don't know what bennyvatten has - his profile indicates an Audi - 1.9tdi.
 

bennyvatten

Member
Joined
Mar 25, 2005
TDI
Audi 80 Avant 1,9tdi
My car is old. It's a 1994 80 Avant with a 1z-type engine. Any details concerning this type and 109-relay?
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
no direct knowledge of what was using in your vintage - I'm just going on the 97-era VW's. We have a relay stamped 109 (sometimes viewed as 601, depending on how it's mounted) and those from that era have proven themselves to be somewhat flakey. If you take a look in your fuse/relay box and see a black cube as shown in compu_85's post above, it is suspect.

That being said, they may have used a different system then - my Bentley's doesn't go to Audi's and not quite that old.

I'd look if I were you. You may also be able to pick up a manual from a used book store - it will come in handy.
 

bennyvatten

Member
Joined
Mar 25, 2005
TDI
Audi 80 Avant 1,9tdi
Thanks for the advice! I'll look into it.Is there any way of telling or testing if it's good or bad?
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
The problem with these, iirc, is in the soldering of the wires in the relay to the plug sections - the joint just starts cracking and failing because of it. Around here they're about US$20 for a replacement from the dealer. You should look to see if you have one to start with. If so, just replace it since it is working - most of the time. This irregularity is one of it's problems, since when it's working you can't test the problem. You can do a search using a 2 year time frame and get enough reading material to keep you busy for quite a while. I don't recall any "fixing" of these, but my memory's not perfect.
 

Doc_Oc

Veteran Member
Joined
Feb 22, 2005
Location
Orangeville, Ontario
TDI
03 Golf TDI
Good to know this is a problem...if your car doesn't start anymore. Why would you change it in advance though? Safety on the highway.
You roll on to the side. What if your tire blows up? I don't think this is such a GREAT issue. There are so many other things that can go wrong in a car and make the engine stall. Are we going to change them all?
Does anybody have a certain statistic on how many of these relays out of a hundred will fail? Does anybody know what is the average life time in 1000 miles of these relays?
A real threat would be if the car would get on fire.
Sorry guys...20 bucks? 1000 clicks. Way more worth it.
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
La Conner, WA
TDI
... None :S
Think of the Ford ignition coil recalls. This was a similar issue... the engine would stall at a random time. Say your passing someone and the engine quits. You loose power steering and quickly loose power brakes. Not that safe of a situation...

-J
 

Doc_Oc

Veteran Member
Joined
Feb 22, 2005
Location
Orangeville, Ontario
TDI
03 Golf TDI
I am not saying is not dangerous. I am saying that the same thing (engine to stall) can happen from 100 other reassons. I am saying that a blown tire is more dangerous than that.
I guess after driving for 5 years for no PS or powerbrakes I don't see this as such a big issue.
Just to be cleare...I thing it is a safety issue...but not that big.
By all means...if it makes you feel safer in your car...20 bucks is not that big of a deal. Just don't expect that your engine will never stall.
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
La Conner, WA
TDI
... None :S
Good point Doc. But if we can spend $20 to prevent a source of failure, isn't it well spent? You wouldn't run your tures 20 PSI low would you?

The realay in the dash, at the top of the relay pannel.
 

frugality

Top Post Dawg
Joined
Sep 19, 2003
Location
Spring Lake, Michigan
TDI
none, 2016 GTI
Bump for an oldie but a goodie. :)

I have a '00 Golf and knew I had the old, black Relay 109, but kept forgetting to get the new, improved, gray one to have on hand if/when the original went out. Well, I got into my car to go to work last week and.........dead. All the lights/windows worked fine, but nothing from the engine. I was pretty sure it was Relay 109 and I was right.

180k miles on the old style Relay 109. Can anyone else top that? :)
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
frugality said:
Bump for an oldie but a goodie. :)

I have a '00 Golf and knew I had the old, black Relay 109, but kept forgetting to get the new, improved, gray one to have on hand if/when the original went out. Well, I got into my car to go to work last week and.........dead. All the lights/windows worked fine, but nothing from the engine. I was pretty sure it was Relay 109 and I was right.

180k miles on the old style Relay 109. Can anyone else top that? :)
180,000 miles from the relay. That's being... Err... Frugal. :D
 

C in Jockland

New member
Joined
Aug 14, 2006
My 1998 A4 2.5tdi (116K) cut out while driving and is now with my local mechanic. Symptoms are that the engine will start but only idle at 500rpm (rough)! No response from the Throttle and this checks out OK on diagnostics. Initial codes were fuel controller fault - which has not returned since being cleared. We replaced the MAF today following a temp fault code yesterday but still no joy. Looks electrical as vacuum pipes and ERG valve checks out OK. This model does not have a Relay 901 - any thoughts .
Thanks
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
C in Jockland said:
My 1998 A4 2.5tdi (116K) cut out while driving and is now with my local mechanic. Symptoms are that the engine will start but only idle at 500rpm (rough)! No response from the Throttle and this checks out OK on diagnostics. Initial codes were fuel controller fault - which has not returned since being cleared. We replaced the MAF today following a temp fault code yesterday but still no joy. Looks electrical as vacuum pipes and ERG valve checks out OK. This model does not have a Relay 901 - any thoughts .
Thanks
Did you look for a relay 109?
 

C in Jockland

New member
Joined
Aug 14, 2006
No Relay 109

901? Looked and then looked again - Seems this model has a 201 relay in beside the ECU. Relay on order will arrive today! However further investigation has shown up Code fault: 01268 - Metering Control N146 Defective (Flow actuator Control Circuit). I am being advised it is likely to be a pump replacement - OUCH!!!!
 

unitacx

Veteran Member
Joined
Apr 7, 2006
Location
Alexandria, VA
TDI
2002 golf
This is for newbies to VW trim.

Turbo Steve said:
Since prevention is much better than redemption, it makes sense to replace the weak Relay 109 ECM Circuit Fuse before it gets too hot and leaves you stranded. The upgraded version of the new Relay 109 circuit has heavier contacts which can withstand the heat better.
There are (obviously) more similar versions than the repair manual pages below suggest


My '00 Golf (should be same as Jetta) has the side clips and a lower panel on the left side of the steering column. The three screws are as shown for the full width lower panel. The 109 relay is visible through the lower panel:


To remove the lower panel, unclip the small fuse door on the left side,

then remove the 3 torx screws,

then remove the larger left side panel, starting with the rear (closest to the back of the car (duh)). The larger left panel has snap-like fastners in the rear, attached to the lower panel, and tabs in the front.

Then with the left side panel off, the lower panel should come out. It also has a set of snap-like fasteners.

The relay can be identified as in the photo. If it says "601" this means that the dashboard is installed upside down, and the instruments were inverted at the factory to correct that mistake. Remove all of the instruments, dashboard, etc. and correct this before replacing the black relay with the light grey one.

I'm not sure if the relay can be reached from below (mine was grey).
 

frugality

Top Post Dawg
Joined
Sep 19, 2003
Location
Spring Lake, Michigan
TDI
none, 2016 GTI
To see where the Relay 109 is, the best way is to open the fuse panel on the left end of the dash and peer behind the fuses with a flashlight. This will give you an idea of where you need to get to.

I believe you can just remove the black panel that's over the pedals, and access the relay. I took off the cowling under the steering column as unitacx did, but I don't think it's necessary from what I read after the fact from a post by MOGolf. Just remove 3 torx screws and remove the black under-panel.
 

Wingnut

Top Post Dawg
Joined
Oct 10, 2002
Location
Toronto & Whitby
TDI
Silver 2003 Jetta Wagon
If you have small hands or good dexterity, you can reach in through the fuse panel and change it. Just pull off the large cover over the fuse panel and you can reach in over top of the panel.
 

SharanTDI

Member
Joined
Oct 12, 2005
Location
Sweden
TDI
Sharan TDI -98 black
I have a Sharan TDI 1998 and the Diesel power relay does not seems to make good contact occationally when I shall start the engine. The start motor works but no fuel injection and no ignition. After a few attemps it will start. If it wount i knock on the central electrical juction box next to the fusebox and it may starts. Sometimes the power goes of for a second or so during the driving. This model has no replaceable relay units. All relays and some integrated circuits are soldered on a PCB-board. The only option is to replace the whole control unit. (expesive piece) I been to some VW workshops and the VAG-COM test show no errors recorded and they cant guarantie that a new unit will solve my problem. I wonder if somone has any idea how to solve this problem?
 

richardtoh

Veteran Member
Joined
Oct 10, 1999
Location
PA
Thanks guys for all the help.
My car died at the parking lot of my local dealer when I stopped by to pick up the Relay 109. My area had been drenched with heavy rain for the few days I finally decided to let the deal install it and perform a state inspection.

I know that, armed with the advice from members here, I would be able to do it myself but I think to do that in a dealership parking lot might cause some discomfort to the business.

Just to share my experience, my Relay 109 died a few days after showing weird symptoms. So if any of you notice that, get it replaced immediately.

Thanks.
 
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