Relay 109 - Main Power Supply Fuse

Ztdi

New member
Joined
Jul 26, 2014
Location
San Diego
TDI
2000 Golf
im wondering if my issue could be relay 109.... i was driving.. got on gas pretty good and all the sudden dash beep and guages drop off... battery light comes on...car started and ran fine afterward and at idle no issue... once i hit accelerator. guages drop and battery light on. 24 hours later of being parked battery dead. thanks. do you think this could be it?
 

TornadoRed

Top Post Dawg
Joined
Aug 3, 2003
Location
Saint Paul (ex-San Diego)
TDI
2003 Golf GL 5-spd, red; 2003 Golf GLS 5-spd, indigo blue; 2003 Jetta TDI wagon, Candy White
im wondering if my issue could be relay 109.... i was driving.. got on gas pretty good and all the sudden dash beep and guages drop off... battery light comes on...car started and ran fine afterward and at idle no issue... once i hit accelerator. guages drop and battery light on. 24 hours later of being parked battery dead. thanks. do you think this could be it?
It could be ... and it's a cheap fix. If it turns out to be something else, then you'll have a spare.
 

bri vw harper

New member
Joined
Aug 28, 2014
Location
yorkshire
TDI
gt tdi 110 1999
ive have a relay 109 issue i had the grey one then got a black one which sorted the problem out for about 200 miles then the same problem has just come back , but this time the car is not starting back up has something else known gone wrong as it cant just be the same relay can it???
 

Passattdi863

New member
Joined
Sep 21, 2014
Location
florida
TDI
Volkswagen Passat
problem with my 2004 Volkswagen Passat tdi

Hey guys I am not really good at using this site but have a huge problem my 2004 Volkswagen Passat in is in limp mode throwing off the code 16629 the car has no pick up to it and is throwing off a emissons workshop on the dash if anyone can help me it would be appreciated I am 1400 dollars in without a fix
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
Hey guys I am not really good at using this site but have a huge problem my 2004 Volkswagen Passat in is in limp mode throwing off the code 16629 the car has no pick up to it and is throwing off a emissons workshop on the dash if anyone can help me it would be appreciated I am 1400 dollars in without a fix
Yo can go to the B5 Passat section and on the left side of the screen is a box to start a new thread. Try there.
 

TownsendTDI

Member
Joined
Dec 7, 2010
Location
Tn
TDI
2000 Golf TDI, 5 spd 2003 Golf TDI, 5 spd
Just wanted to say a huge "Thanks!" for this thread! I picked up a relay 109 5 years ago when I bought my car and read this. Then today, my car just cranked and wouldn't start. It's very well maintained, and couldn't imagine what it could be. Then I remembered that relay in my parts box in the back, popped it in, and she cranked right up! It had a little blip and felt like the engine "missed" one or twice the trip before, I'm glad it didn't die in traffic and waited till I got home, definitely should have installed it before it gave me trouble!
 

powerfool

Veteran Member
Joined
May 25, 2012
Location
Indianapolis Metro Area
TDI
None anymore
Does anyone have a list of replacement relays, in general?

My concern is that the previous owner had shoddy maintenance performed on my car. I have three different relays that are labelled "53" in my car and I am not sure if that is normal or if they simply bought extras and used these in the place of the proper ones... I am not sure either way, but I am looking to just replace all of my relays at this point, being at over 200k miles.

EDIT: I found this: http://web.mit.edu/dennis/www/vw/relays.html

Does that seem accurate? It looks like it lists 3 different "53" relays, so that is promising.
 
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LittleBlue

New member
Joined
May 21, 2014
Location
Beaverton, Oregon
TDI
2000 golf
Relay 109 once again...

Many thanks to my wonderful cousin "Whitedog"!:)
At 7:30 last night I pinged him with the question...
No glow plug light but cranks and never starts.
less than 2 minutes later was his succinct reply "relay 109" .
I had this issue a little over a your ago on my 2000 Golf and now it had raised it's ugly little head on my daughters 2000 golf and more importantly I had completely forgotten about it!:eek:.
Short version is that I had a spare in my glove box and from his response to getting the car starting was 13 minutes!
THANKS CUZ, I owe you once again!
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
It would have been 11 minutes if your autocorrect hadn't said "it will start".

Stupid technology!
 

jagster936

Veteran Member
Joined
Nov 8, 2007
Location
Texas
TDI
2002 Beetle TDI Manual
I always get the fun ones. Every day once or twice, the engine will briefly cut out for no more than one second. It's nearly the same every time. I thought maybe it was getting air bubbles in the fuel pump but then I noticed the TACH would drop out and then recover, again never more than one second in time. If it was a loose wire I would think it would be more random lengths of time. It seems to do it mostly when warming up.

I do have Malone stage 1 tune. Any ideas what could cause this? It seems to be ECU related or possibly a sensor, the tach thing is really strange though and is a clue!

I guess I may have to log it with VCDS every time I drive and catch it, but what parameters should I log?

I am going to go ahead and replace relay 109 to rule it out, I think.

Thanks
 

bobpaul

Member
Joined
Feb 9, 2007
Location
North Dakota, USA
TDI
2002 Jetta TDI
Could this be my problem?

My symptoms were a little different than what most of the people in this thread have been reporting... I was driving 2002 l when headlights, gauges, interior lights and engine all turned off. No click or anything from the keyswitch that I noticed. But when I went under the hood, the radiator fans were still running. After 20 minutes or so, it came back to life and I was able to drive a whole mile down the road before it happened again.

Does that match a possible symptom for the 109 relay? I found someone with the exact symptoms as me, but he has a 2006 and the faulty relay for him is under the hood. Should I be looking somewhere else?

edit: No, my symptoms are not indicative of a relay 109 problem
In my case it was the fuse box on top of the battery. The 2nd fuse from the left (S176) is a 110a fuse that powers the entire fuse box next to the driver's door. Tightening that down solved the problem for now. I'll be replacing that fuse box I think.
 
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bobpaul

Member
Joined
Feb 9, 2007
Location
North Dakota, USA
TDI
2002 Jetta TDI
So as an emergency road repair, you can jumper the fuse connector from fuse 12 to fuse 28 and bypass relay 109 altogether. Just pull the wire when you shut off your car...

Fuse 12 is the unswitched power source for DLC.
I have a 7.5a in 12, but no fuse in the slot for 28. Is that normal and expected?
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
300k miles on the '03 Jetta and this is the first time (I think...) that it's let me down.

About 6 weeks ago, 4 blocks from home after sitting overnight, cool start (60F) the car shuts off, just like you turned the key off. Cycled the key and it fires back up and no further issues until Friday when leaving work.

It was about 40F out and I rolled the key over and crank, crank, crank no start. Try it again and noticed no Glow Plug light. Try it a few more times and get it to start and it dies, couple more times and it runs fine the 24 miles home. Forgot about the issue over the weekend, went to go to work this morning and no Glow Plug light, no start.

Pulled 109 relay, popped the cover off, looks brand new inside, contacts clean, etc. Re-install - can feel it click and can manually hold it closed, still no Glow Plug light and no start.

Take the TT to work, get home tonight, review the wiring schematics, find nothing amiss, fuses 32, 34 and 43 are good, have power when the key is on, 109 clicks like it did before, car fires right up.

So...now what? I've got no problem getting a new 109 relay but until then I'll bring a jumper with me just in case.

No Glow Plug light and sudden engine off seems like 109 and this agrees with the schematics, however I can't make sense of why it wouldn't start this morning with the relay engaged.

Thoughts?
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagen, 2021 Atlas,2003 Jetta 261K Sold but not forgotten
Check fuse 176 on top of the battery.
Its 110 amp.
Make sure the connections are tight & clean.
Check for power on both sides of it.

On the fuse box inside the car Check the 2 heavy terminal that relay 109 plugs into.
One should have power all the time. (key off)

If you look close on the relay (inside) there was a plastic block that on mine that was preventing the contact lever to make a good connection.
I sanded it down and it worked fine until I got a replacement relay.
Just wanted the old one to be a spare. :)
 

rotarykid

Top Post Dawg
Joined
Apr 27, 2003
Location
Piedmont of N.C. & the plains of Colorado
TDI
1997 Passat TDI White,99.5 Blue Jetta TDI
I just had one of these fail last week in rush hour Denver traffic in my 99.5 Jetta, ~162k on the clock... Thankfully there were two guys walking down the road that pushed me out of traffic into a parking lot. It Took me longer to find the tools to remove all that plastic than it did for me to pop it out to take the relay apart. Once I got it apart I re-installed it shorting it together to get the car home.

I brought the malfunctioning relay inside putting on my magnifying glasses to get a good look, seeing the failure was from two broken soldered main curcuit board connections....

I fixed the broken connections, ~500 miles later with no issues since....

I still plan to get & carry with me a backup relay if this ever happens again, hopefully it never will again.....
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagen, 2021 Atlas,2003 Jetta 261K Sold but not forgotten
I think I would put the new relay in and keep the old repaired one as a spare.
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
I'm pretty sure it's not the 109 relay. It did it again last week and I was able to re-confirm power at the 3 fuses that the relay powers as well as feel the relay click in with each key cycle and there was NOT a glowplug light on the dash.

Let it sit with the key on for a few minutes, cycle the key and the GP light comes on and it'll fire up.

ECU starting to go flakey maybe? Seems to only happen below freezing - not sure if this is causal or not, but something I noticed.

More puzzle pieces as I find them :)
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
It's a balmy 13F this morning - no glow plug light :( = crank but no start

Check fuses 32, 34 & 43 again - power on both sides, verified 109 is functioning, it is, replace it anyway, still no glow plug light :(.

Look at the schematics and the only other interaction that the glow plug module has is with the ECU, so since I have a few ECU's I figured I'd swap in a different one.

Well, the cowl plastic, connectors and wires are rather stiff when it's 13F so I warmed up the cowl plastic with a hair dryer for a few minutes, lifted it up and aimed the hair dryer at the ECU connectors for ~20 minutes. Came back out and it was nice and warm to the touch, not hot at all, easy to remove like usual.

New ECU fired right up - BUT - remember I warmed things up so we'll wait until tomorrow morning when it's supposed to be 8F to see if I've fixed anything.
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
It was 8F this morning - glow plug light came right on, let the glow plugs run (shorter than the previous ECU) and it fired up on the 2nd revolution and ran on all 4 immediately. The previous ECU didn't start that good at 28F with longer glow time.

We'll give it a few more days to prove itself, but right now it's looking like a slowly failing ECU or possibly an electrical connection that cleaned itself as the ECU connectors were removed and re-installed.
 

jagster936

Veteran Member
Joined
Nov 8, 2007
Location
Texas
TDI
2002 Beetle TDI Manual
Nice thanks for sharing this. Assuming this isn’t tuned.


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Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
So to rule out either the ECU or the wiring/connections, when I got home tonight I swapped the previous ECU back in the car. The theory being that if it was an electrical connection that cleaned itself, the previous ECU should work fine. If the previous ECU still did not start, then it was a bad ECU.

Did the swap - no glow plug light, no start. Put the new ECU back in and it started right up again. I had forgotten about my 6 bar MAP sensor yesterday so I ended up driving back and forth to work in limp mode which was interesting. So after I got done swapping ECU's around tonight I put the 4 bar MAP in which (I think?) this ECU is tuned for.

Interestingly with the new ECU, besides starting better, the car idles smoother, runs better (for the few seconds before limp mode comes on), etc. Here I was thinking that my 200K mile injection pump was going bad and/or my 150k mile nozzles were tired causing the hard starting, white smoke, rough running, etc and it seems that the ECU was the issue?

Has anyone ever had an ALH ECU go bad? I've not heard of it that I can recall?

jagster936 - These ECU's are tuned. I've got a couple from Rocketchip, one from Malone, one from TDTuning.
 

jagster936

Veteran Member
Joined
Nov 8, 2007
Location
Texas
TDI
2002 Beetle TDI Manual
Wow! Good information. I haven’t heard of that. Good to know people with extra ECUs also [emoji48]


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