99.5 stalling, ECM appears 'dead'

atomic777 · May 25th, 2006, 20:45

Hey everyone,

I have a rather troubling problem with my 99.5 jetta tdi.

While driving, for no apparent reason, something seems to short out and the car will die. When the short happens, often i will just get a bit of a hiccup, see the glowplug light for a split-second, and the car will keep going. Usually this is a warning that a bigger stall is coming. Today I was stuck on sunset blvd (not a fun place) for a good 2-3 minutes, trying in vain to start. When I turn the key to the start position, I won't see the glow plug light flash even for a second, and I know the car is not "ready" to start. After waiting a while it will come back and I can start the car again without a problem.

I was lucky to have the car in this 'dead' mode when I got home and hooked my vagcom. Much to my surprise, when the car is in this 'zombie' mode where I don't get the glowplug light indicating that I can start, my VAGCOM can't even get a connection to the ECM, it's as if it's not there. After a while when it comes back to life, I can connect without any issue, and I get no codes other than the cruise control switch problem and the charge pressure/control deviation 17958. (I'm having the symptons of a N75 issue on my car going into limp mode, which have been getting worse in the last week or two. Not sure if it's related though.)

I also checked the sticky on TDI 101 for the anti-shudder valve being stuck, and this is a different issue. My car will crank indefinitely when in this dead mode. Putting the anti-shudder valve into the stuck position still gives me the glowplug light when I put the key into the ignition position, so I know that's okay.

Anyone have any other ideas for things I can check, or is this something I need to take it into the shop for? (Any good mechanics on the LA Westside?

MOGolf · May 25th, 2006, 20:47

This is known as a failing 'relay 109' problem. A search will reveal lots of reading on this topic.

compu_85 · May 25th, 2006, 20:54

atomic777 · May 25th, 2006, 21:04

MOGOlf thanks so much... you've likely saved me 100's of dollars. With the scare i got today, i'd have gladly paid a lot of money to be certain the problem would go away.

atomic777 · May 25th, 2006, 21:06

compu_85 you read my mind! I was just wondering if i'd be lucky enough to find a picture of what it looks like

compu_85 · May 25th, 2006, 21:31

Couple of torx screws and the dash pannels come off. The relay pannell is right there.

The new gray relays have the 109 printed upside down compared to the old black ones.

-Jason

LNXGUY · May 25th, 2006, 22:11

Jason, have you had any probs with your relay 109? *crosses fingers* I got 218,000 miles and mine hasn't done a thing...

compu_85 · May 25th, 2006, 22:26

I changed mine at ~130K. I hadn't had any problems, and didn't want to have any

I had to get an accessory belt from Impex anyway and added a 109 to the order. I took the old one apart and it still looked great inside. I should keep it in the trunk I guess... It's sitting on the table downstairs.

When I took it apart, it looked different inside then the one GeWilli took pictures of. The solder joints looked a little bigger, and the board was shaped different. His golf is a real early 99... mine is a real late 99, so I wonder if there was a partial update at some point?

-Jason

atomic777 · May 25th, 2006, 23:05

I'm amazed that such a trivial part could do so much damage and be of such poor quality. An inopportune stall could quite possibly get someone killed... for a $20 part. What if my engine died as I was making a left turn on a busy intersection?! This is Hyundai-level quality control, not what I expect from a German car. Not to mention the stupid faulty N75 I have which has reduced my car to a 45hp tractor, I'm basically driving a Lada right now. What good is a bullet-proof engine that will last 500k if I can't rely on a basic relay to keep the ECM powered?!

Sorry, these two stalls today have really soured my mood....

ofhs93 · May 26th, 2006, 05:06

Welcome to the wonderful world of VW electronics....the engineering has always been great...the electrical execusion...well...let's not go there. N75 should not be too difficult to replace...why not just order it with the 109 and git r' done?

atomic777 · May 26th, 2006, 22:48

Glad to report that I replaced the black 109 relay with a shiny new grey '601' relay, and my car ran for a 30min test drive without any problem.

Not sure if it's my imagination, but the car seems to be running a bit smoother now; appeared to start easier and i wasn't getting as much smoke out the tailpipe going uphill as I used to. Also never went into limp mode and had full power the whole time. Could a nearly-dead 109 have a connection to such problems or is this all in my head? From this thread, http://forums.tdiclub.com/showthread.php?t=31070, it seems this relay is providing power to a lot of pretty critical things, including the N75.

In any case, thanks a bunch to everyone that helped!!

bcres978 · March 6th, 2010, 13:26

Ok I just tried the 109 relay to fix a computer issue my car failed inspection because they said the computer cant read my cars diagnostics so I tried the local autozone ant the OBD-II wont connect either any ideas?

MOGolf · March 6th, 2010, 13:34

Blown fuse 12?

atomic777 · March 6th, 2010, 14:00

Doesn't sound like the issue i had -- the VAGCOM couldn't connect when the relay was cutting out, which prevents the car from running entirely

Dave_D · March 7th, 2010, 05:05

Quote:

Originally Posted by bcres978

Ok I just tried the 109 relay to fix a computer issue my car failed inspection because they said the computer cant read my cars diagnostics so I tried the local autozone ant the OBD-II wont connect either any ideas?

Do you have an aftermarket radio/deck in the car? If so, you need to check the wiring. You can verify this is the problem by disconnecting the radio/deck and seeing if you can connect with VAG-COM/OBD-II then.

Dave