SOLVED: Crank - No Start, No Glow Plug Light, No MIL Light, Low Voltage at Fuse 29 to ground

[bhef]

So my 2000 Jetta TDI refuses to start besides the 2 times out of probably 40 tries.

Symptoms:
1)No MIL Light
2)No Glow Plug Light
3)No power to relay 109 fuses
4)No Start (Will crank just fine)
5)Programmer cannot communicate with ECU
6)Fuse 29 only weakly illuminates test probe light
7)Windows fail to roll up or down (worked at first when having no start problem)
8)Relay 109 will not engage with key turned to ON


NOTE: Called dealer who saw this car before I bought it and said "loose wires under dash. Just wiggle them around"
-Tried this so many times and only once did it briefly cause the glow plug light and MIL light to illuminate with key turned to on (still no start)


What I've done:
Confirmed power to relay 109 (12.4V)
Confirmed relay 109 works by swapping with one from working vehicle (1st try the car started and only once since then)
Confirmed fuses are good
Checked for power at corresponding fuses powered through relay 109 (only power present when manually engaging relay I took the cover off of)
Confirmed good ground at relay 109 socket (VERY little resistance, audible continuity setting beeps)
Checked for evidence of mice chewing wires in engine bay (none found)
Checked grounds under battery (great condition)
Checked fuseable link fuses on top of battery (all good no resistance across)


What I have left to try:
Confirm continuity to ECU from relay 109 on the small blue wire (rig dummy wire up between those components to confirm the wire is bad if dummy wire fixes problem)
Confirm Socket pins are not loose so that relay actually makes full contact on every blade


ANY help and direction would be so appreciated and if anyone can tell me how much power is sent to relay 109 from ECU or if the relay actually sends power to the ECU that would be helpful. Basically, if someone could explain how the ECU (and what requirements are needed for) ties into activating relay 109 that would be great

I JUST got this car and it's amazing when it worked before this problem last night causing me to need a tow home. Roughly 190hp manual conversion NO corner cut in restore/tune/mod/conversion/perf upgrades. Only 40k miles on everything except frame, body and window glass. PLEASE help me get this back on the road.

 

[mittzlepick]

Loose wires probably refer to conversion job, persnicikty dealer service notes

 

[mittzlepick]

Check for voltage to fuelpump shutoff

 

[bhef]

No voltage at fuel distribution shutoff.

So I've done more trouble shooting and realized that with ground the test light illuminates fuse 29 (Engine management) weakly with key in ON position. measuring voltage across there is no voltage so I'm thinking bad ground there and then that would mean no ground signal from ECU to relay 109 so no start.

Where does ECU ground enter and where is power wire for ECU located?
I need to get into that because when I test voltage to ground NOT across fuse 29 there is only 5V. Should be 12V

 

[bhef]

So from quick internet search its in the plenum chamber right next to ECU. I will be pulling the plenum and checking for ground to ECU from there and then power to fuse 29. Fuse 29 and Fuse 5 both splice from the ignition switch. will be checking fuse 5 for voltage across fuse. Maybe it's a bad ignition switch or bad splice

 

[tdidieselbobny]

Try a new ignition switch. One going bad can cause many funky things. Easy to access without pulling steering wheel. 4 small phillips screws hold the column trim pieces on - 2 each side and 1 torx above the tilt handle on bottom of column. lift top cover up. let bottom one hang on tilt handle. You should see 2 red paint marks on the lock column, scrape paint off and use tiny flat blade to turn those 2 set screws out some to pull the switch out( underneath the turn stalk)...

 

[bhef]

UPDATE:
fuse 5 also has no current across and 5V to provided ground so that splice seems good

ECU has ground with very few ohms or none for all ground pins except for one which has 25 Ohms (not sure if that is an issue or the issue here

I really think this is a bad ignition switch at this point due to airbag light going on and off with no rhyme or reason for a week before issue, window switch working and then not working back and forth with no apparent reason, and the low/no power to ecu. also, power to mirrors not working any longer now. Lastly, the switch has become very hard to turn to ON if I leave it alone for 5 minutes. at times I feel I might break the key.

Going to pull steering wheel cover to check ignition switch for burnt blades and also test switch wires for resistance/see if they are burnt.

 

[bhef]

Try a new ignition switch. One going bad can cause many funky things. Easy to access without pulling steering wheel. 4 small phillips screws hold the column trim pieces on - 2 each side and 1 torx above the tilt handle on bottom of column. lift top cover up. let bottom one hang on tilt handle. You should see 2 red paint marks on the lock column, scrape paint off and use tiny flat blade to turn those 2 set screws out some to pull the switch out( underneath the turn stalk)...

I can't believe it took me until about 30 min ago since this problem started to decide to try a new one out. Your timing is perfect. Thanks man

 

[bhef]

Try a new ignition switch. One going bad can cause many funky things. Easy to access without pulling steering wheel. 4 small phillips screws hold the column trim pieces on - 2 each side and 1 torx above the tilt handle on bottom of column. lift top cover up. let bottom one hang on tilt handle. You should see 2 red paint marks on the lock column, scrape paint off and use tiny flat blade to turn those 2 set screws out some to pull the switch out( underneath the turn stalk)...

took it out. wow so easy.

Nothing looks burnt. I turned it to ON and get ~50 Ohms between battery supply and fuse box blade. Should this be close to zero??

Ohms look good around 2 when testing continuity between other blade for battery and "B+ to load reduction relay"

No continuity between any blade and blade 86s which works for power windows, radio, and instrument cluster

Have no idea what this all means. any insight is much appreciated

 

[PakProtector]

There should be no high resistance connections. Either nearly zero, or open circuit. Good luck, but I think you have the issue in hand. Check the Bently, stuff that is supposed to go from open( OFF) to closed (RUN ) should be near zero.
cheers,
Douglas

 

[tdidieselbobny]

Order it from IDPARTS or Rock Auto, Napa, Advance, Autozone are close to $60 for it, if they even have one...

 

[tdidieselbobny]

Forgot to mention it’s a little easier if take left knee panel out...

 

[bhef]

Tested wire to Fuse 29 and 5 socket from ignition switch connector (share same wire before splice to ignition switch) and it shoes full continuity (0.1 ohms) resistance. All wires look good as far as I can tell and so does connector sockets for ignition switch. I'm am picking another switch up in a couple of hours. Will report back when new switch is installed

 

[bhef]

Forgot to mention it’s a little easier if take left knee panel out...

Already had all of that out to get into relays and whatnot. Thank you, nonetheless.

And yes, I'll shop around.

For now, I know a guy who led me to the PO of this car so I could buy it. He owns a used car lot specializing in VWs, and AUDIs. He has so many spare parts. He said I could grab a known working one from his assortment of parts to try. I'm doing this because the soonest I can get a new one without driving 80 miles is Monday and I want this resolved ASAP.

 

[tdidieselbobny]

Get a new one ordered, leave everything apart. It's a crap shoot with any used one....

 

[bhef]

Get a new one ordered, leave everything apart. It's a crap shoot with any used one....

Certainly will. Trying to get ahold of local VW dealer to see if they have new in stock. If not, will order one. Friend who owns car lot gets 35% discount on parts from dealer and told me I can use the discount through him.

 

[bhef]

Guy didn't end up having the switch so I got a cheap china one until the OEM comes in. I'll have a backup too just in case this happens again.

PROBLEM SOLVED

Fired up easier than ever before.

Have ~12.5V to ground at Fuse 29. Let it warm up to try hot and it started up just as well. So far 3 good starts, power windows and mirrors both work again.

What a PITA this ordeal was, but after it's said and done I'm stoked with how much I learned about how the car works/runs and how much I leveled up my electrical diagnosis skills in general.

Thanks to everyone who replied. Much appreciated


Diesel exhaust never smelled so good.