Alaska Green Jetta - My First MK4

[P2B]

Well.... I attempted the procedure (numerous times) in the video.. and I discovered that the second key fob does not electronically unlock the doors...it will lock them electronically occasionally.. and it will not lock from a distance of 10 feet like my 1st (original ) key does.. both of them have new batteries in them.

Does the unlock button register (LED flash) on the fob?

 

[Jesterking]

Does the unlock button register (LED flash) on the fob?

Both Fobs emit a red light when either button is pressed

 

[PradoTDI]

On my fob only the lock and trunk buttons work intermittently, the unlock button never works. This weekend the trunk latch mechanism quit working, forcing me to crawl in through the back seat and remove the trunk lid liner to unlatch the trunk. I pulled the latch motor out and hooked it up to my bench top power supply, it works perfectly. The correct lights flash when I pull the trunk release button or push the button on the fob, but no power is getting to the latch motor.

Upon further investigation, the "trunk open" dash light does not illuminate when the trunk is open, and the license plate lights aren't working, so I suspect the trunk harness might be bad. Does anyone know how to get at the harness where it goes into body by the tail light? If there's a plug in there somewhere I can get at I'd like to check the harness for continuity before pulling the whole thing out. I suspect the wiring might be shorted here:

IMG_7347.jpeg

• PradoTDI
• Tuesday at 5:26 PM

I was able to adjust the linkages from the key lock to the latch mechanism, so at least now I can open the trunk with the key instead of crawling through.

IMG_7348.jpeg

• PradoTDI
• Tuesday at 5:26 PM

 

[P2B]

On my fob only the lock and trunk buttons work intermittently, the unlock button never works. This weekend the trunk latch mechanism quit working, forcing me to crawl in through the back seat and remove the trunk lid liner to unlatch the trunk. I pulled the latch motor out and hooked it up to my bench top power supply, it works perfectly. The correct lights flash when I pull the trunk release button or push the button on the fob, but no power is getting to the latch motor.

Upon further investigation, the "trunk open" dash light does not illuminate when the trunk is open, and the license plate lights aren't working, so I suspect the trunk harness might be bad. Does anyone know how to get at the harness where it goes into body by the tail light? If there's a plug in there somewhere I can get at I'd like to check the harness for continuity before pulling the whole thing out. I suspect the wiring might be shorted here:

IMG_7347.jpeg

• PradoTDI
• Tuesday at 5:26 PM

I was able to adjust the linkages from the key lock to the latch mechanism, so at least now I can open the trunk with the key instead of crawling through.

IMG_7348.jpeg

• PradoTDI
• Tuesday at 5:26 PM

The wires break at the flex point above the hinge. I just slice the rubber cover open, repair the wires inside, add a piece of plastic to spread out the flex point, and cover with electrical tape.

 

[d24tdi]

Or maybe there's a ground strap somewhere that is loose or broken? Kind of weird that every single function in the trunk lid is being disabled at the same time despite it being several different circuits, and it doesn't sound like any of those circuits are giving hard shorts to the other stuff they are tied to (running lights etc)? That would make me think of the ground point for the circuit, wonder if that's something that could be found in the wiring diagrams. I've got the Bentleys for the Mk4 if ya need to go digging!

Old Volvo 240 wagons were notorious for breaking the tailgate hinge wiring due to a poor design that exposes the wires to too much flex, leading to incremental failure of the functions in the tailgate, but usually they'd fail one by one as the individual wires broke. Lose the wiper, then the defroster a few weeks later, then the license plate lights after that.... Usually something would keep working intermittently too. Definitely a little odd that everything is totally and consistently dead.

Interesting to read the immo discussion. I was told one time years ago by someone who is a fan of keeping immo active that once you disable immo, you are no longer able to pair new keys to the cluster. Of course that doesn't really matter too much once you no longer need the immo to run the car and can use any key that's cut correctly. But there was some kind of valid downside he brought up, maybe someone who is commenting here knows.

 

[d24tdi]

Ah, well there's good info from @P2B that sounds like the answer.... Interesting, not a failure I have ever seen but of course that is with a small sample size. Maybe some cars get unlucky in how the wires happen to lay up in the harness and fail faster....

 

[PradoTDI]

The wires break at the flex point above the hinge. I just slice the rubber cover open, repair the wires inside, add a piece of plastic to spread out the flex point, and cover with electrical tape.

That's a great idea, I'll see about pulling a bit of harness out of both sides to make some room to work.

 

[PradoTDI]

Or maybe there's a ground strap somewhere that is loose or broken? Kind of weird that every single function in the trunk lid is being disabled at the same time despite it being several different circuits, and it doesn't sound like any of those circuits are giving hard shorts to the other stuff they are tied to (running lights etc)? That would make me think of the ground point for the circuit, wonder if that's something that could be found in the wiring diagrams. I've got the Bentleys for the Mk4 if ya need to go digging!

Old Volvo 240 wagons were notorious for breaking the tailgate hinge wiring due to a poor design that exposes the wires to too much flex, leading to incremental failure of the functions in the tailgate, but usually they'd fail one by one as the individual wires broke. Lose the wiper, then the defroster a few weeks later, then the license plate lights after that.... Usually something would keep working intermittently too. Definitely a little odd that everything is totally and consistently dead.

Interesting to read the immo discussion. I was told one time years ago by someone who is a fan of keeping immo active that once you disable immo, you are no longer able to pair new keys to the cluster. Of course that doesn't really matter too much once you no longer need the immo to run the car and can use any key that's cut correctly. But there was some kind of valid downside he brought up, maybe someone who is commenting here knows.

Looking at how things are wired in the trunk lid it appears the trunk metal is not used as a ground, so maybe the ground wire in the harness is broken at the hinge point. That would explain the complete failure of all electronics in the trunk all at once.

 

[P2B]

Looking at how things are wired in the trunk lid it appears the trunk metal is not used as a ground, so maybe the ground wire in the harness is broken at the hinge point. That would explain the complete failure of all electronics in the trunk all at once.

Definitely at least one ground wire in that bundle.

 

[wonneber]

Or maybe there's a ground strap somewhere that is loose or broken? Kind of weird that every single function in the trunk lid is being disabled at the same time despite it being several different circuits, and it doesn't sound like any of those circuits are giving hard shorts to the other stuff they are tied to (running lights etc)? That would make me think of the ground point for the circuit, wonder if that's something that could be found in the wiring diagrams. I've got the Bentleys for the Mk4 if ya need to go digging!

Old Volvo 240 wagons were notorious for breaking the tailgate hinge wiring due to a poor design that exposes the wires to too much flex, leading to incremental failure of the functions in the tailgate, but usually they'd fail one by one as the individual wires broke. Lose the wiper, then the defroster a few weeks later, then the license plate lights after that.... Usually something would keep working intermittently too. Definitely a little odd that everything is totally and consistently dead.

Interesting to read the immo discussion. I was told one time years ago by someone who is a fan of keeping immo active that once you disable immo, you are no longer able to pair new keys to the cluster. Of course that doesn't really matter too much once you no longer need the immo to run the car and can use any key that's cut correctly. But there was some kind of valid downside he brought up, maybe someone who is commenting here knows.

I wonder if there would be codes with this if you had the key on & tried the unlock and lock functions through the door window and try to open and close the trunk a few times.

 

[burpod]

No, MPPS is for flashing the ECU. @gmenounos software (kw1281test) is free and can disable the immobilizer and program keys.

You can use mpps v18+ to delete the immobo

 

[PradoTDI]

You can use mpps v18+ to delete the immobo

I knew I had seen that somewhere! I did go ahead and download kw1281test, need to do some reading to get a handle on how to use it. Programming keys will likely be the primary use for me, all 4 MK4's in the family could use an additional key.

I'm planning on just doing an immobilizer delete on my car, since it has been inconsistently causing trouble. That's the one thing I worry could leave me stranded.

 

[PradoTDI]

Finally ran an auto scan on the car yesterday, came up with a few different codes:
Engine:
17978 - Engine Start Blocked by Immobilizer
- P1570 - 35-10 - - Intermittent
16512 - Coolant Thermostat Valve (N214)
- P0128 - 35-10 - Temperature below Control Range - Intermittent

Airbags:
00532 - Supply Voltage B+
- 07-10 - Signal too Low - Intermittent

Instruments:
01176 - Key
- 07-10 - Signal too Low - Intermittent

Central Convenience:
00930 - Locking Module for Central Locking; Rear Left (F222)
- 27-00 - Implausible Signal

Would the 01176 Key signal too low be due to a weak fob battery, or does it have to do with the immobilizer and key talking to each other?

 

[P2B]

Would the 01176 Key signal too low be due to a weak fob battery, or does it have to do with the immobilizer and key talking to each other?

No, key and fob are separate items in the same housing. That code was probably set due to low vehicle battery voltage, same cause as the airbag code. Try clearing them and see if they come back.

The P0128 means your thermostat is stuck open or partially open, needs replacing.

 

[PradoTDI]

Checked the coolant temp reading with the car cold (ambient temp around 12ºC) and it came back with -13.5ºC. After idling for 5-10 minutes while I explored various measuring blocks in VCDS the coolant temp reading was up to around 50ºC. Cleared DTC's in all modules and the only one that came back so far is the 00930 for the rear left locking module.

I checked on the door switches in the CCM and neither of the LH side doors are working. Since the LR door lock doesn't work either, I am planning on just ordering both door actuator modules. As the darkness of winter closes in around here it would be nice to have working dome lights!

 

[P2B]

Checked the coolant temp reading with the car cold (ambient temp around 12ºC) and it came back with -13.5ºC. After idling for 5-10 minutes while I explored various measuring blocks in VCDS the coolant temp reading was up to around 50ºC.

Seems the ECU element of the CTS reads low. Did you check the cluster side in VCDS?

 

[PradoTDI]

Seems the ECU element of the CTS reads low. Did you check the cluster side in VCDS?

I did, actually, it read 20ºC before starting the engine. Perhaps both parts of the sensor are bad? I'll be opening up the cooling system before too long for some other work, so I could swap in a new CTS then.

 

[P2B]

I did, actually, it read 20ºC before starting the engine. Perhaps both parts of the sensor are bad? I'll be opening up the cooling system before too long for some other work, so I could swap in a new CTS then.

Personally I would do a thermostat and CTS and be done.

 

[PradoTDI]

Picked up a FrostHeater for a MK5 TDI on Craigslist for $20, new in box. I emailed FrostHeater and they sent me a conversion kit to use the kit in a MK4.

IMG_0291.jpeg

• PradoTDI
• Wednesday at 7:04 PM

 

[csstevej]

Nice find !