VW 2005 mk4 Jetta - Hood Latch Question

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rbb1485

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Hello all,
So on my 2005 VW Jetta wagon 1.8t I do not get a confirmation "beep" when I lock the car. I first thought it was due to faulty door lock modules because I had signal communication error codes to several doors, and intermittent locking issues, I have since replaced them all and all are now in working order. Upon my last replacement, I went to do the celebratory lock anticipating the "beep" and to my disappointment I did not receive it (although all doors lock/unlock now correctly, so that was a plus). I then used my lovely VCDS and measuring block 08 in central convenience and noticed the front hood latch showed "open" even though the hood was shut. Ahhhhaaaa! So while looking at measuring block 08, with hood open, i manually clicked up and down on the hood latch contact switch, and sadly the measuring block value stayed at "open". So I thought to myself, OK, easy fix, i'll just purchase a new hood latch switch + harness.

Fast forward to today, before tearing apart the front grill + hood latch assembly, I simply unplugged the harness at the easily accessibly harness connector (front of engine bay on passenger side) and plugged in the new OEM one. Started up my VCDS, went to measuring block 08, and clicked the contact switch up/down and the valued stayed at "open". !! :mad: I then thought, OK maybe it is a defective part (unlikely) so I tested the new part on my older 2003 VW jetta and sure enough the value in VCDS went from "open" to "close" etc etc. So i know the new OEM switch (and most likely the original is good too). I then grabbed my trusty test light, unplugged the connector and found with the ignition ON (engine off) on my older 2003 VW jetta I get +12V on pin #2 (brown wire with red stripe). I then go repeat this test on my 2005 mk4 jetta and wouldnt you know I do not have power at pin #2 !!

So I start trying to trace this wire all over the engine bay, tearing things apart and thanks to my lack of electrical wire tracing skills, cannot find where it terminates or really where it even leads too.

So my question to the VCDS community is this: Can I make a program / coding change to trick the car to think it is a always "closed" signal ? This would avoid tearing apart wiring looms trying to find where the single wire is open? Oh and I should mention before I started tearing thru, I was able to de-pin the #2 to inspect the crimped connector and all was secure with a good connection.

If I cannot, does anyone have a clue where this wire has a common failure point? FYI, my full auto scan is below:


Code:
Sunday,28,July,2019,20:24:04:53404
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 7 x64
VCDS Version: 19.6.1.0 (x64)  HEX-V2 CB: 0.4508.4
Data version: 20190529 DS308.0
www.Ross-Tech.com


VIN: WVWSE61J25W010683   License Plate: BR76LB
Mileage: 273120km-169708mi   Repair Order: 



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 1J (9M - VW Jetta IV (1998 > 2014))
Scan: 01 02 03 08 09 15 16 17 19 22 29 35 36 37 39 46 47 55 56 57
          75 76
 
VIN: WVWSE61J25W010683   Mileage: 273120km-169708miles
-------------------------------------------------------------------------------
Address 01: Engine        Labels: 06A-906-032-AWP.lbl
   Part No: 06A 906 032 SK
   Component: 1.8L R4/5VT     G   0030  
   Coding: 07500
   Shop #: WSC 01266  
   VCID: 79AF10D230C45B0F8D7-5160
   WVWSE61J25W010683     VWZ7Z0D9180863

3 Faults Found:
16804 - Catalyst System; Bank 1 
            P0420 - 35-10 - Efficiency Below Threshold - Intermittent
16795 - Secondary Air Injection System 
            P0411 - 35-10 - Incorrect Flow Detected - Intermittent
16840 - EVAP System 
            P0456 - 35-10 - Very Small Leak Detected - Intermittent
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels: 1C0-907-37x-ESP-F.lbl
   Part No: 1C0 907 379 M
   Component: ESP FRONT MK60      0102  
   Coding: 0019970
   Shop #: WSC 01266 785 00200
   VCID: 3431E1E6522666671E1-5184

No fault code found.

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 6Q0-909-605-VW5.lbl
   Part No: 1C0 909 605 F
   Component: 17 AIRBAG VW61 0108 0003  
   Coding: 12599
   Shop #: WSC 01266  
   VCID: 270B06AA96F01DFFAB3-513C

No fault code found.

-------------------------------------------------------------------------------
Address 16: Steering wheel        Labels: 1J0-907-487-A.lbl
   Part No: 1J0 907 487 A
   Component: Lenkradelektronik   0005  
   Coding: 00118
   Shop #: WSC 01266  
   VCID: 2F3BEE8ABE0045BF633-5184

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 1J0-920-xx5-17.lbl
   Part No: 1J5 920 906 J
   Component: KOMBI+WEGFAHRSP VDO V03  
   Coding: 05232
   Shop #: WSC 00000  
   VCID: 3431E1E6572666671E1-513C
   WVWSE61J25W010683     VWZ7Z0D9180863

No fault code found.

-------------------------------------------------------------------------------
Address 19: CAN Gateway        Labels: 6N0-909-901-19.lbl
   Part No: 6N0 909 901 
   Component: Gateway K<->CAN    0001  
   Coding: 00006
   Shop #: WSC 01266  
   VCID: 70B92DF663BE1A473A9-513C

1 Fault Found:
01332 - Door Control Module; Passenger Side (J387) 
            49-10 - No Communications - Intermittent

-------------------------------------------------------------------------------
Address 46: Central Conv.        Labels: 1C0-959-799.lbl
   Part No: 1C0 959 799 C
   Component: 8A Komfortgerát HLO 0004  
   Coding: 00259
   Shop #: WSC 01266  
   VCID: 372BD6EA46508D7F3B3-4B1E

   Subsystem 1 - Part No: 1C1959801A
   Component: 8A Tõrsteuer.FS KLO 0202  

   Subsystem 2 - Part No: 1C1959802A
   Component: 8A Tõrsteuer.BF KLO 0202  

   Subsystem 3 - Part No: 1C0959811A
   Component: 8A Tõrsteuer.HL KLO 0202  

   Subsystem 4 - Part No: 1C0959812A
   Component: 8A Tõrsteuer.HR KLO 0202  

1 Fault Found:
00930 - Locking Module for Central Locking; Rear Left (F222) 
            27-10 - Implausible Signal - Intermittent

-------------------------------------------------------------------------------
Address 56: Radio        Labels: 3B7-035-1xx-56.lbl
   Part No: 3B7 035 180 G
   Component:    Radio PM6        0016  
   Coding: 04031
   Shop #: WSC 01266  
   VCID: 241111A6E7C6F6E78E1-513C

No fault code found.
I know this is small potatoes, but i am a mechanical engineer and it bugs me when a system is designed in a certain way and it does not perform as expected! Cheers and thank you for reading!
 
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rbb1485

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Oh and FYI, on my correctly operating 2003 jetta, while viewing measuring block 08 with the hood open, the value shows "open". When I unplugg the connector, it switches to "closed". On my 2005, with the connector plugged in or unplugged it always stays at "open". So obviously this +12v wire has a continuity issue somewhere but god only knows where or how I can find it!!
 
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rbb1485

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Just to throw up my latest auto scan:
Code:
-------------------------------------------------------------------------------
Address 16: Steering wheel        Labels: 1J0-907-487-A.lbl
   Part No: 1J0 907 487 A
   Component: Lenkradelektronik   0005  
   Coding: 00118
   Shop #: WSC 01266  
   VCID: 2F3BEE8ABE0045BF633-5184

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 1J0-920-xx5-17.lbl
   Part No: 1J5 920 906 J
   Component: KOMBI+WEGFAHRSP VDO V03  
   Coding: 05232
   Shop #: WSC 00000  
   VCID: 3431E1E6572666671E1-5160
   WVWSE61J25W010683     VWZ7Z0D9180863

No fault code found.

-------------------------------------------------------------------------------
Address 19: CAN Gateway        Labels: 6N0-909-901-19.lbl
   Part No: 6N0 909 901 
   Component: Gateway K<->CAN    0001  
   Coding: 00006
   Shop #: WSC 01266  
   VCID: 70B92DF663BE1A473A9-5160

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv.        Labels: 1C0-959-799.lbl
   Part No: 1C0 959 799 C
   Component: 8A Komfortgerát HLO 0004  
   Coding: 00259
   Shop #: WSC 01266  
   VCID: 372BD6EA46508D7F3B3-4B1E

   Subsystem 1 - Part No: 1C1959801A
   Component: 8A Tõrsteuer.FS KLO 0202  

   Subsystem 2 - Part No: 1C1959802A
   Component: 8A Tõrsteuer.BF KLO 0202  

   Subsystem 3 - Part No: 1C0959811A
   Component: 8A Tõrsteuer.HL KLO 0202  

   Subsystem 4 - Part No: 1C0959812A
   Component: 8A Tõrsteuer.HR KLO 0202  

No fault code found.

-------------------------------------------------------------------------------
Address 56: Radio        Labels: 3B7-035-1xx-56.lbl
   Part No: 3B7 035 180 G
   Component:    Radio PM6        0016  
   Coding: 04031
   Shop #: WSC 01266  
   VCID: 241111A6E7C6F6E78E1-5160

No fault code found.
I've read the CCM can get a "hiccup", and to clear it you can try disconnecting battery + and - leads and briefly touching them together to clear the "hiccup". Not sure if I should try this or not....
 
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Uwe

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So my question to the VCDS community is this: Can I make a program / coding change to trick the car to think it is a always "closed" signal ?
I don't think so. Those early CCMs aren't smart enough to have much in the way of programmable option.

Proper investigation would involve the use of a wiring diagram. But if you're convinced that the the problem is a missing +12V on the one side of the switch, how about running a new wire there, at least temporarily, for testing purposes)? I'd put a 1 amp in-line fuse in that wire just to be sure you don't fry anything.

I've read the CCM can get a "hiccup", and to clear it you can try disconnecting battery + and - leads and briefly touching them together to clear the "hiccup". Not sure if I should try this or not....
This often helps when those CCMs get into a mode where they don't talk to a scan tool, but I'm skeptical that it will help here. OTOH, it can't hurt much to try it either.

-Uwe-
 
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rbb1485

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I don't think so. Those early CCMs aren't smart enough to have much in the way of programmable option.

Proper investigation would involve the use of a wiring diagram. But if you're convinced that the the problem is a missing +12V on the one side of the switch, how about running a new wire there, at least temporarily, for testing purposes)? I'd put a 1 amp in-line fuse in that wire just to be sure you don't fry anything.


This often helps when those CCMs get into a mode where they don't talk to a scan tool, but I'm skeptical that it will help here. OTOH, it can't hurt much to try it either.

-Uwe-
Hello Uwe,
Thank you for your response, truly appreciated. I have in fact pulled the wiring diagram from my bently manual, I'll post a pic below. The hood latch switch F120 is a simple 2 wire switch....1 wire (brown/red) to the CCM, and 1 (brown) a ground connection in headlight wiring harness.

I am sure that there is to be a +12V with ignition ON as i checked this on my correctly functioning 03' jetta, and this same test on my 05' wagon results in no +12v. So If i understand your suggested test, are you saying to run a 1 amp fused "test wire" with a +12v directly to the appropriate lead in connector going to the switch? Do I then manually depress the hood latch contact lever up/down and watch the measured value in block 08? Expecting it to change between "open" and "close" ? And if this is successful, that confirms I have a continuity issue in the brown/red wire going to the CCM ?

I will start tomorrow by simply touching the + and - battery leads, as you confirmed this cant hurt anything.

Thank you again.


 
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Uwe

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I am sure that there is to be a +12V with ignition ON as i checked this on my correctly functioning 03' jetta, and this same test on my 05' wagon results in no +12v. So If i understand your suggested test, are you saying to run a 1 amp fused "test wire" with a +12v directly to the appropriate lead in connector going to the switch?

Do I then manually depress the hood latch contact lever up/down and watch the measured value in block 08? Expecting it to change between "open" and "close" ? And if this is successful, that confirms I have a continuity issue in the brown/red wire going to the CCM ?
Yes, that's what I was suggesting.

BUT! Based on the wiring diagram you posted, it looks to me like the other side of that switch goes to a GROUND connection in the headlight harness, not +12.

-Uwe-
 
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rbb1485

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Hi Uwe, yes that is how I read it as well. So what test would you suggest now? Thanks
 
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rbb1485

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Just to provide an update. On my correctly functioning 03' jetta, when checking voltage with a multi-meter across wires T2a/1 and T2a/2 on the F120 hood latch switch, I get a steady +8V at all times. When I repeat this test on my problem 05' wagon, I do not get any measurable voltage.
 
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Zenerdiode

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T2a/! and T2a/2 aren't on the switch itself. They're a plug-coupler that your WD says is near the right headlight. That's a good place to start and narrow down your testing. Personally, there's possibly a whole load of the green crusties in that coupler that's causing things, but please test properly. At the coupler, separate it and test from T2a/1 to ground with a multimeter on resistance. Also test its current-carrying potential using an incandescent test light with the croc clip on the Bat + and the probe on T2a/1.

Next, at the same plug-coupler, short T2a/2 to ground whilst watching the Measuring Blocks on VCDS. Report back please.
 
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rbb1485

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Thank you Zenerdiode. here are my results:
Test T2a/1 to ground = I am getting around a 5.5ohm resistance.
Current carrying potential = Incandescent test light LED shows steady "green"
Short T2a/2 to ground while watching measuring block on VCDS = the value does not change from "OPEN"
 
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Zenerdiode

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...and that's at the connector near to the headlight? :confused: Does it look clean, without corrosion? Photo?

If so, your next port of call is the connection to J393 - at T15/1. If you can, use a back-probe and get a connection to the terminal in chamber 1. Test its voltage with respect to ground. Short it to ground whilst viewing VCDS MVB. Unplug the 15-pin connector, test from terminal 1 (T15/1) and T2a/2 on resistance.
 
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rbb1485

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Hi Zenerdiode, to answer your qeustion, yes it is the hood latch switch connector plug near (in my case) passenger side (right) headlight. See photo:



With it unplugged you can see the spade terminals appear to be without corrosion, no green corrosive stuff you had mentioned earlier. See picture:



Corrosion was one of my first thoughts, so I actually de-pinned the signal wire (brown/red) to inspect the crimped spade connector and all looked good, very nice clean connection. I actually did not do the same however for the ground (brown) wire. I will do that next. High resistance from this wire to ground makes me think maybe bad ground connection in the headlight harness where it tries to find ground, or the wire itself is compromised?

Before I go tearing the front dash apart to find J393 (this will have to wait until at least next weekend), would it be appropriate to simply add a new ground using a wire tap off of the brown T2a/1 wire to a chassis point in that location? I know this is not the "proper" fix, but is this a logical approach?

lastly, not sure what you mean by a "Back-probe" ? Thanks again
 
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rbb1485

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Actually, thinking about it more, adding a new ground from a wire tap off of brown T2a/1 wire would not help the situation, as I still do not have voltage present at the T2a/2 pin....correct? Its a mute point to fix the ground when I do not have the voltage I should have coming in...
 
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Zenerdiode

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Ah, thank you for posting the pictures; they are indeed worth a thousand words. :)

Yep, ~5Ω is a little high, but we know that doesn't need addressing yet, as shorting T2a/2 directly to ground isn't toggling the indication.

Back-probing is where a connector remains connected to its receptacle; (so all other power, ground, sensor and actuator wires remain connected) and a thin probe is passed into the connector to the pin under test, from the back of the connector. I appreciate it is not always possible with the style of wire seals on some connectors in harsh environments, but with J393 being inside the cabin, it maybe just possible.
 
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rbb1485

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Hi Zenerdiode,
Okay I now understand what "back-probing" is. I was actually wondering that this morning how I am I supposed to test T15/1 voltage at J393 with respect to ground with it still plugged in....now it makes sense! I will order a "back probe kit" from good ole trusty Amazon.

So hopefully this weekend I will perform the next logical tests to trouble shoot this issue:
1) Test T15/1 voltage with respect to ground. What should I expect to see in the measuring block whilst shorting it to ground?
2) Unplug 15 pin connector and confirm signal wire continuity by measuring resistance from terminal 1 (T15/1) to T2a/2

Will report back! Thanks again!
 
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rbb1485

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Also, could anyone shine a bit more detail as to what the physical connection point of "B161 - Connector (anti-theft warning system) in wiring harness interior" is....looks like.....location....? This Saturday, I plan to first backprobe T15/1 at J393, if I do get voltage there with respect to ground, my next thought is there is something going on with this "B161" connector.... as I believe (will confirm) I have voltage at T8/1 on the radio 8 pin connector. Thanks!
 
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DV52

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^^^^rbb1485: I know nothing about the mk4 Jetta, but I am enjoying (in a perversely voyeuristic way) reading your unfolding story with zenerdiode. It's a kind-of master-class in fault diagnosis - very well done indeed!!!:popcorn:

Anyhow - enough of the hagiography (as the saying goes) - with my opening comment as a caveat (i.e. my ignorance in matters Jetta related), here's an extract that might shed some light on your question



If I read your WD correctly, B161 looks like one of these "welded connections" - I think. As to where this little beastie is in the car's wiring loom - I'll leave that answer to someone who actually knows the car intimately!!

Don
 
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The exact location of those points is not given in the wiring diagrams unfortunately, only the general location (dashboard wiring loom or interior wiring loom for example).
 
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rbb1485

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Hi all, thanks for the feedback! Well on to the next troubleshoot tests results:
1) Test T15/1 voltage with respect to ground --> Using my new "back probes" i was able to measure voltage at T15/5 (oddly enough the red/brown wire was in terminal 5 location, not 1 as the WD shown) and i got 0.01V, and the MBV of the hood switch F120 showed "OPEN" the entire time......confirmed I had a good ground by testing another terminal and got 12V.

2) Unplug 15 pin connector and confirm signal wire continuity by measuring resistance from terminal 1 (T15/1) to T2a/2 --> The resistance dropped to nearly 0ohms (~0.5ohm) so I believe the 0.5mm red/brown signal wire is intact and OK

I then removed the CCM entirely from the vehicle, and opened it up to inspect for any water damage, corrosion, and oddly enough it looked very clean, all good solder joints, etc. Below are the actual photos:





So I guess my next step is to match a used CCM from a wagon and picked one up from ebay or something, any other thoughts? Thanks again
 
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Dana

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Make sure that Radio is fully seated/locked into the dash. If memory serves one of the locks on the right side is directly tied to the switch that powers your hood latch switch.
 
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