109 relay symptoms

DSlaunwhite

New member
Joined
Mar 16, 2018
Location
Nova Scotia
TDI
2003 TDI, 2011 TDI, 2001 TDI
Hey

I have read quite a few posts regarding the 109 relay problems and the symptoms that go along with it. I have a 2003 Jetta ALH. That has all the classic symptoms of faulty 109 relay. I have changed the 109 relay with 2 others that worked on other cars. No Change. I thought it may be the ECU so I changed that, still no change. When I jump terminals 30 and 87 on the block where the 109 goes The car will start, but if left connected it will kill the battery. Any ideas what to check next. If there is an answer somewhere on this forum can someone post the link.

Thanks.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Other than the apparent start issue, what are the other symptoms?
 

Mongler98

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Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
?????
your buying a used relay from a parts car? DUDE, its a 5 /4 pin simple 30/40amp relay. like $8 for a pack of 5 on amazon. dont get a used one, paint or write 109 on it if you want to feel happy about it.

So on to your issue. First off, replace it some times does not work, on my mk3 the issue was that the socket was getting worn out. I had to take it apart and solder in new pins into the harness block and that involved a LOT of work to get to it. But if yours is not corroded, just get a tiny pick and get the seat to be a bit more tight for the relay prongs, a supper thin needle nose pliers works also.

symptoms of 109 being bad
no 12v to the shut off solenoid to open. there are a host of other things for the ip, and what not that run off that relay from the ECU, your getting voltage at the relay on the 12v side right and NOT the other side right?

just fix the connection it makes and get a new relay for like $2 on amazon
 

ToxicDoc

Veteran Member
Joined
Mar 1, 2018
Location
Virginia, US
TDI
2001 Jetta, S7, .216
Well I suspect it's a 100% duty cycle relay, so not just any generic one. Some reliable brand would be ideal
 

KLXD

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Joined
Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
:rolleyes:

Idunno. If I were troubleshooting and had access to a relay from my other car I wouldn't waste time waiting for Amazon to ship me one.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Any time I am at the U-pick junk yard, I grab any and all Relay 109s. The dude basically gives them to me. Then, I install and see if they work. If so, they become emergency spares! Seems one of my friend's 01 Golf is still running with on of those old used 109s from at least 4 years ago!

But, as Mongler98 said, they are cheap... even the name brands offered by the Vendors that are a part of this community!

The OP needs to give us some more clues!:D
 

DSlaunwhite

New member
Joined
Mar 16, 2018
Location
Nova Scotia
TDI
2003 TDI, 2011 TDI, 2001 TDI
109 relay

other symptoms.... The glow plug indicator will not come on with the key and when I connect the computer interface cable it has intermittent connection errors. no connection to the controller. that is all I can think of right at the moment. :confused:
The other 2 109's relays I have tried have been from 2 other
jetta's that I have in the family that are working fine. Didn't see much since in buying a third. :)
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Here's some good reading on the Relay 109. Drafted this when I was doing the TDI install in my Vanagon.

Relay 109 and associated Circuits (Based on 2002 Jetta TDI)

Located at Position 12 in the upper relay panel
Relay 109 is identified as J317, Power Supply from Terminal B+ (hot at all times) with power activation by the ECU when the key is in the ON position.

Power Circuit to Relay 109
1. Power (6.0 size red wire) comes from Fuse S176 (110amps) at the plastic box on battery to Threaded Connection 500 at the relay plate -1- (30). (fuse panel under dash)
2. From the Relay Plate, at Connection 501 (not 500) the power (6.0 size red wire) goes to Splice A98 (buried in the wiring harness)
3. From Splice A98, the power (4.0 size red wire) goes to Terminal 2/30 of Relay 109

Relay Circuit (activated when the Ignition is turned ON)
1. Connection 9/85 goes to Blue Connector T10h/8 on to ECU at T121/18 (So, another power source to the ECU provides the current to Activate the Relay 109 which in turn activates the rest of the ECU.....make sense?)

Power Circuit "away" from Relay 109
1. Power away from Relay 109 (Terminal 6/87) is via 4.0 Blue Wire to Splice A71 (internal of the wiring harness)
2. At Splice A71, there are three circuit branches (A, B, & C, my terminology)
Circuit - A. 1.5 Wire goes to Fuse 34 (10 amp)
Circuit - B. 4.0 Wire goes to Fuse 32 (30 amp)
Circuit - C. 1.5 Wire goes to Fuse 43 (10 amp)

Circuit A (with two branches) ........ engine operation functions
From Fuse 34 goes to Splice 100, first branch provides power to: MAF (G70), Wastegate Bypass Regulator Valve (N75), EGR Vacuum Solenoid Valve (N18) and Change-over Valve for intake manifold flap (N239) Note: tied to this same circuit, is another circuit with a 1.0 size wire that goes to connection 6/87 of the GP relay. The second branch , Splice 100 goes to the 14 Pin Connector at T14a/6 on to Cold Start Injector (N108)

Circuit B (with two branches)
From Fuse 32 goes to Splice B168, first branch (4.0 wire) goes to Brown Connector point T6/4 on to splice D74 and provides power to: ECU at T121/1 and T121/2 via the two branches at Splice D74. The second branch goes to the 10 pin connector at the Injection Pump (G149), connection T10f/5

Circuit C (with three branches)
From Fuse 43 goes to Splice A155 , the first branch goes to Clutch Vacuum Vent Switch (F36). The second branch goes to Brown Connector at T6/6 with double wire of which one goes to a 53 Relay J359 for Low Heat Coolant GP and the other goes to the Positive Crankcase Ventilation Heating Element (N79). The third branch goes to the Brake Vacuum Vent Valve Switch (F47)
 

 

Alchemist

Veteran Member
Joined
Nov 3, 2007
Location
Lethbridge, Alberta
TDI
'04 ALH Golf
Check fuse 29. If it is good, check for 12V on it when the key is on. This is the signal from the ignition switch that wakes the ECU up and causes it to turn relay 109 on. If there is no 12V at fuse 29, it is probably a bad ignition switch.
 

DSlaunwhite

New member
Joined
Mar 16, 2018
Location
Nova Scotia
TDI
2003 TDI, 2011 TDI, 2001 TDI
109 Relay

I did all the checks suggested and still nothing. So I started chasing the blue/yellow wire from the 109 relay block back to the ECU. Found the problem!:) I wouldn't have believed it. Inside the harness about 1/2 way along there was a small deformation in the insulation. pulled in the wire and it came apart wire was broken. Cleaned it up put it back together and it works great.
Thanks for the help
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
I did all the checks suggested and still nothing. So I started chasing the blue/yellow wire from the 109 relay block back to the ECU. Found the problem!:) I wouldn't have believed it. Inside the harness about 1/2 way along there was a small deformation in the insulation. pulled in the wire and it came apart wire was broken. Cleaned it up put it back together and it works great.
Thanks for the help
I TOLD YOU to check the connections. i had this problem in similar form. glad you got it fixed. Cheers. good work!
 

Powder Hound

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Joined
Oct 25, 1999
Location
Under a Bridge, Crestview, FL, USA
TDI
'00 Golf 4dr White 5sp, '02 Jettachero 5sp, Wife's '03 NB Platinum Gray auto(!)
That wasn't a connection, that was a continuity problem, which is even more difficult to find when the wire insulation is intact.

Without an obvious clue such as a rodent chew site, this is a VERY difficult problem to find.

Nice work!

Cheers,

PH
 

algirdas

Veteran Member
Joined
Jan 23, 2009
Location
Cincinnati,OH (Dubwerx)
TDI
98 jetta AHU
Just had the same problem with 03 ALH. Would crank but no start and no glow plug light.
Turned out to be a broken wire in the harness that triggers the 109 relay.
It was the blue/yellow wire from ECU connector to the blue plug in plenum passthru.
Fixed by running an overlay wire using Vw wire repair crimp kit.
 

ELM

Veteran Member
Joined
May 25, 2011
Location
Sutter Creek CA
TDI
2002 Beetle 5 speed swap
I have 02 Beetle that had a no start problem but it would turn over. It wasn't getting power to the fuel shut off valve on the injection pump and it ended up being the 109 relay that was bad.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
I have 02 Beetle that had a no start problem but it would turn over. It wasn't getting power to the fuel shut off valve on the injection pump and it ended up being the 109 relay that was bad.
Glad you got it going ...
 

Randomhomelesstdibeetlegu

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Joined
May 12, 2022
Location
Stinking onion land
TDI
00 ALH Tdi
I know this thread is ancient and I want to thank AndyBees immensely. Your analysis saved my ass with my junk beetle that wreaks like hobo stank.

Anyways I discovered the early ALH or at least my early ALH had what looks like 16 gauge terminal 30 feed to the 109 relay and 16 gauge out blue to the 3 fuses and current paths. A new 109 relay ran super hot scary too hot to touch. I found the very undersized wire and took the fuse 32 circuit and isolated it to its own relay 109.

I used 10 gauge and ring/spade terminals crimped soldered to feed terminal 30 fuse panel power to the 30 side of the relay. I had only a 12 gauge inline fuse to put on the 87 out of relay 109 so I made it short and soldered 10 gauge to the 10 gauge on the side of fuse 32 that goes to injection pump and a t6 connector in the plenum.

You read that right. Fuse 32 in my beetle is 10 gauge out to the motor and 14-16 coming into it with a 30amp fuse.

🤮

Now the isolated relay 109 runs super cool to the touch and my motor even sounded different after ran smoother etc etc. No joke.

This thread and data saved my homeless divorced self. The ALH is eternal.

I left what Andy calls circuit A and C on the old relay 109 wiring with a repaired cleaned old white 109 relay. Guess what? This still gets hot. Too hot to touch for long.

Once I validate components I am likely doing the same with larger fresh not 20 year old undersized wire. I need to look again but the fuse 34 and other blue wire branch looked super small going to each fuse.


I am going to do this right with actual oem relay sockets in the relay panel and thick wire straight from terminal 30.

Also the battery fusebox to relay panel cable seems undersized for everything in the car heated seats etc.

If you have issues beyond relay replacement look at this, especially I'd you have a beetle or early car. Andy did an 02 harness.

Oh to add the new relay and repaired old one both ran super hot on factory wiring even after isolating. Just hopefully can help someone else in a bind. This was after doing a melted ignition switch harness properly far back with a low mileage clean donor and loads of other electrical repair. These cars are old enough they need this level of repair now.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Wow! I'm glad the info I posted was helpful.

Thanks very much for sharing your work and findings. Honestly, I never realized that the 109 Relay gets hot. Actually, I've never given it any thought. But, considering that relay is prone to fail, likely heat is the primary contributing factor.

In the photo below, if you will look real close, near the center of those wires, you will see a large red wire with a lilac stripe and then to the left of it is a Small Blue Wire ... Yep, that's a screw-up during assembly. The Large Blue Wire to the right and behind the taped bundle was supposed to have been inserted in place of the smaller blue wire! Those wires were flipped during the assembly process. IIRC, the large wire carries current to the ECU!

Those "blue wires" are "feeds" from the 109 Relay.

 

Randomhomelesstdibeetlegu

Veteran Member
Joined
May 12, 2022
Location
Stinking onion land
TDI
00 ALH Tdi
Wow! I'm glad the info I posted was helpful.

Thanks very much for sharing your work and findings. Honestly, I never realized that the 109 Relay gets hot. Actually, I've never given it any thought. But, considering that relay is prone to fail, likely heat is the primary contributing factor.

In the photo below, if you will look real close, near the center of those wires, you will see a large red wire with a lilac stripe and then to the left of it is a Small Blue Wire ... Yep, that's a screw-up during assembly. The Large Blue Wire to the right and behind the taped bundle was supposed to have been inserted in place of the smaller blue wire! Those wires were flipped during the assembly process. IIRC, the large wire carries current to the ECU!

Those "blue wires" are "feeds" from the 109 Relay.


I'll get.pictures later but my 00 beetle had three BABY blue feeds to the three ecu fuses. Then fuse 32 out is 10 gauge red with a purple lilac stripe.

The heat has to be from undersized old wiring but get this! The ends had no signs of heat or corrosion no strange bends or obvious breaks inside insulation.

I don't think they are even enough for the maf and various bits on circuit A bit C being switches should be fine. Either way it shouldn't be this hot once I verify nothing is excessively drawing it has to be old dated bad wire in a poor factory design.

This should be stickied as I bet a lot of cars were junked over this.

Are the early golf/Jetta cars like this with undersized wiring?
 

Randomhomelesstdibeetlegu

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May 12, 2022
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Stinking onion land
TDI
00 ALH Tdi
90 degrees out and so far has not left me stranded and died with no crank signal or signal break up and ECU cycling.

I do feel something is amiss with circuit A as that super hot relay is possibly causing issues with engine electricals still on that current path.

The car left me stranded 4 times the past week over this issue. Now it has a slight misfire and stutter that is probably a power issue to the MAF/N75/ASV.

Correct me if wrong but would circuit A power cuts cause the ASV to flutter shut? I can't remember if the valve is normally open or closed.

I also refuse to delete the ASV as I do not need a runaway. So has to be fixed.

I hope someone else can benefit from this because of how long it drove me mad and how intermittent and heat related this was. It would still die some during cool weather but traffic and heat was a guaranteed 30-60 minute cool down to restart and strand you again later.

Pics:
 

Randomhomelesstdibeetlegu

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Joined
May 12, 2022
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Stinking onion land
TDI
00 ALH Tdi
And it died out twice but only when "cold" or in warmup mode with the blue coolant light. so perhaps the N108 circuit is malfunctioning now. Time to get proper wire to the other two circuits.

I get strong tach signal when cranking and it wants to catch after a while of cranking.

Prior to this when it died you'd have weak or no tach signal likely due to power cutting of the ECU fuse 32 k
 

Randomhomelesstdibeetlegu

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Joined
May 12, 2022
Location
Stinking onion land
TDI
00 ALH Tdi
14.2-3 volts at ECU and the red purple 10 gauge out fuse 32 from new wiring mods.

N75 N18 still on old wiring? 13.2v or so. That's a lovely voltage drop.

Have to wire around that factory wiring for fuse 34 later. May as well do circuit c also. 🤔

Still a dying junk.

Had a cheap fuse half blow as well for circuit B. Replaced with a decent one.
 

Randomhomelesstdibeetlegu

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Joined
May 12, 2022
Location
Stinking onion land
TDI
00 ALH Tdi
Removed the injection pump connector seal and gained .5 volt at the start stop solenoid when running. That has swelled up and is causing very difficult locking of the connector and pushing the connector apart causing pins not to seat fully.

Next up is finish this:








Thin blue wire is the extended yellow/blue ECU trigger wire for relay 109. This is quick and dirty to get it running and minimize movement of spade connectors now crimped very tight to terminals.

Literally going to heat shrink and solder the two relay 85 terminals together daisy chained and leave it until I get parts to do this in the relay panel properly.

This should get rid of the resistant and voltage drop in the ancient undersized blue wires, because all are gone.

I still think some of the wire going out is undersized... Oh well it should be fine and better than new.
 

Randomhomelesstdibeetlegu

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Joined
May 12, 2022
Location
Stinking onion land
TDI
00 ALH Tdi
Top relay is getting a 10 gauge inline fuse holder and redone/shortened out to fuse panel. Was sort of proof of concept and all.

This would probably last forever but later this year I'll do it proper with oem ends and less bodge.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
The fuel shut-off (start-stop solenoid) get's full voltage when the ignition is first turned On. Then, the voltage will drop very fast to 0. Keep in mind, this is just with the ignition On. Obviously, the voltage doesn't go completely to zero with the engine running.

Below are 4 photos taken in about 15 seconds from beginning to end. (voltage at the Fuel Shut-off Solenoid)







 
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