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Thread: 2005 VW Jetta TDI BEW no cruise control

  1. #11
    NostraJackAss Jack@European_Parts's Avatar
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    Anything is possible, but why speculate? Fix the things that obviously need fixing anyway first. I think there's a good chance that doing so that one of them (the ABS sensor or the Cam Position Sensor will restore a speed reading to the ECU. Once the ECU is showing road speed again, if the cruise still doesn't work, them we can pursue other possibilities.

    -Uwe-


    Agreed but re-coding a login authorization doesn't but take a few seconds too check too and can be done with VCDS for the price of nothing?
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  2. #12
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    I've become quite familiar with the daisy-chain VSS wiring in BEW automatics from doing a few manual swaps with them.

    The BEW in the Golf/Jetta that comes bolted to the 09A transmission are pretty backwards from how VSS is normally wired on VAG engines from the era.

    Most Mk4s that don't have the Jatco 09A transmission (whether it be a manual or 01M 4 speed auto) are wired with the G22 VSS going straight to the cluster, then the cluster sends the VSS on another wire to the ECU.

    The Jatco transmission does not have the traditional G22 VSS on the differential. It uses the transmission output speed sensor, sends the signal to the TCM, the TCM then repeats the info to both the cluster and engine computer directly, on separate output wires from the TCM.

    So, if the TCM sees the VSS as well as the instrument cluster, I can see 3 possible issues. Either the wire between the TCM and ECU for the VSS is broken or otherwise damaged to the point of being unable to carry the VSS signal, or the TCM is not outputting the signal correctly... or the ECU is not recognizing it internally for some other reason.

    I suppose at that point the only way to really narrow things down from there if you can't find fault with the wire is to use an oscilloscope to verify if the TCM is at least outputting the signal to the ECU on the correct wire, then you'll know if it's a TCM or ECU issue.

    Looking at my notes from one of the BEW manual swaps I did awhile back, T68a/63 is the VSS output from the TCM (T68a being the code the wiring diagram uses for the 68 pin TCM connector, pin #63). Should be a blue/purple wire, but don't just go for any blue purple wire, as there are more than one. Make absolutely sure it is pin 63.

    It goes to T94/90 at the ECU (T94 being the larger, 94 pin connector at the ECU, pin #90). The smaller ECU connector is a 60 pin (aka T60).

    Check for continuity between those two pins, do a pin drag test as well, make sure the terminals on either end aren't spread. If everything there checks out OK, then either play the guessing game with replacing the TCM or ECU, or try and use an oscilloscope to at least verify if the TCM is ouptutting the VSS signal to the ECU.

    For the record, the official VW wiring diagrams do NOT show this correctly. I had to find this out the hard way when I was doing a manual swap and verify continuity with a meter to figure out with absolute certainty how the factory had it wired. Most of the 09A diagrams that do show in more detail the VSS signal only really give you the info for the gas engine wiring between TCM and ECU (J220 instead of J248) and the pin number IS different.

    So, I found where the VSS wire is supposed to go on the manual trans wiring (comes from the cluster on the manual), used the automatic trans diagram to figure out where the output wire from the TCM is, put two and two together and verified with the meter.

    EDITING TO ADD:

    It is unusual to not see a code in the ECU for no vehicle speed signal. Normally when they don't see vehicle speed, it sets a code.

    Beyond that, you can easily verify the pedal switch positions and cruise control switch positions looking measured value block 006 in the engine computer. Knocking out a few more possibilities for inop cruise control.

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  4. #13
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    As I scrolled down further in the log, I noticed you actually had some MVB 006 info. Now, it doesn't tell me if the Set and Res switches are working, but it is at least recognizing that the system is switched ON.

    The one thing that does concern me, again not knowing the status of what you were doing while the snapshot of MVB 006 was taken, field 2 which has pedal monitoring:

    00101100 Cruise Control Pedal Monitoring

    Here's what I have to decode that for PD measured values:

    xx1xxxxx means the main cruise switch is on
    xxxx1xxx cruise control enabled
    xxxxx1xx CLUTCH SWITCH ACTUATED

    If that last one quoted (bit 2, counting from the RIGHT, the first bit being considered bit 0, then counting 1, 2 etc) was done with you NOT pressing the clutch pedal, that is a problem that needs to be addressed. That's a bad clutch switch or a broken wire between clutch switch and ECU.

    It's not unusual for the later blue clutch switches to break if someone has removed it before and attempted to reinstall it. I see it a LOT. In order to properly remove and reinstall one of those switches, you should press the clutch pedal far enough so the switch pin is fully extended, THEN twist the switch out. It has an odd, overcomplicated auto-adjust mechanism to it and if you attempt to reinstall the switch without that pin being properly, fully released, IT WILL BREAK UPON REINSTALLTION. End result being that it's either shorted on full time, or broken contact altogether.

    To test if at least the wiring itself is OK, you can watch measured value block 006, unplug the switch and jump the two pins together yourself. Normally with the pedal released, that wire should be sending 12V to ECU at T94/43. And when it is sending 12V properly, MVB 006/2 should look like xxxxx0xx. And when the 12V is taken away, it should look like yours with xxxxx1xx.

    The other thing to check is if you're getting voltage in the first place TO the switch. It's technically a 4 pin connector, but only has 2 wires going to it, pins 2 and 3.

    Pin 3 is your voltage in, blue/yellow wire. Pin 2 is signal out to ECU T94/43, white/red wire.

    If you're not getting voltage on the blue/yellow wire, check fuse 43.

    Though if that were also bad you'd also have half your brake switch not being recognized correctly... and there's a few other items that fuse powers as well (crankcase vent heater, O2 sensor, control side of the coolant glow plug relays, which DOES set a code on BEWs--once again found that out the hard way doing auto to manual swaps).
    Last edited by dieseldub; 10-21-2019 at 05:25 PM. Reason: Adding more info

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  6. #14
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    Thank you all for your help so far. I now have to take a 1500 mile round trip to take in less than 2 weeks, so I really appreciate the help on figuring this out lol. I'll try to answer everything the best I can.

    I've got the cam sensor ordered to fix the P3007 code (should be in on Thursday. Whether or not it's this issue, I agree that it's an issue that does need to be fixed), and I haven't had any ABS issues since replacing the sensor. I will check the tail lights just to be sure since that's easy enough to do. I'm unsure what's meant by FOD tuning, but I'll attempt to send the CC enable code because it can't hurt. I'm also unsure what G40, and G45 are, however the brake light switch is functioning normally. I've checked that one over several times. For the blocks on my first post, I believe that the car was parked and idling. For the second, the car was moving while I was trying to set the cruise. I'll get another autoscan after work tomorrow, and I'll make a note of everything to be more specific. Also, the car is an automatic, so no clutch pedal switches.

    Regarding the wiring and the controllers, can you tell me where the controllers are mounted at? Also, I'm assuming the VSS output from the TCM is a standard square wave as seen on a scope? I actually have one, and can check it. TBH I'm kind of surprised the vehicle speed isn't transmitted between controllers over the datalink wires, however that would make sense as to why I can pull the data from the TCU and not the ECM. As far as whether it's a switch, I don't think it is. The only one that the car should have since it's an automatic is the brake light switch, and I've checked that one for function repeatedly as I've seen that switch cause issues on trucks. I don't think the clutch switch bit in group 006 should affect anything since the car is an automatic, and I checked the coding to verify that the ECM was coded for the right transmission (I don't remember which part of the code set this, but I went off of the pop-up list in VCDS to verify everything was set properly), however at this point nothing would surprise me. I'll start going through the wiring once I have a chance to pull the car into my shop, which will likely be a couple days as we're pretty busy right now unless the ECM is easy to get to. Also, is there anywhere I can get the diagrams you mentioned? I shouldn't need it thanks to the pinouts and instructions you gave, however I like having the correct wiring diagrams onhand because this is a car I bought with 300k miles for $800.

    As far as the cruise control switches and pedals go, the car was most likely idling in park if you are referring to my first post. I did take snapshots while it was moving, however I did notice that it seems to consistently show I have the clutch pushed in until it hits about 40mph. I'll double check it tomorrow after work to make sure that is the case, and post an autoscan of it with some more specific notes. Again, the car is an automatic, so I would think the ECU would ignore that bit either way. I believe the first post has logs I took of the ECU, TCU, and ABS controller while driving where I had marked each time I tried activating the cruise control. On the autoscan of my second post, I took snapshots of groups 006, 002, and 010 in the ECU, and groups 001, 002, and 003. I chose these groups based on what I've read in other forums, as well as what groups had data that I've needed with similar issues on trucks. All the logs there are at operating speed, with the first few at about 45mph, and the last few at 70mph. I did have it log data while going down the highway while trying to set the cruise control. If you need more data or info, just let me know and I'll get it. Here's a link to download the .CSV fire that VCDS generated from it: https://www.mediafire.com/file/u42zv...ceng3.CSV/file

    Now, this might be a stupid question, but could the code stored in the TCM (01045 Tiptronic Switch - Implausible Signal) be related to this? I just realized nobody has said anything about that one. The way I understand it, that code just means the shift lever isn't reading when I move it over to manually set a gear, and it shouldn't affect anything other than that one feature.

    EDIT: Does anybody know if there are common spots in the wiring harness where it rubs through, or other trouble spots? Also, could this be an issue with a bad ground somewhere? If so, where are the factory grounds?
    Last edited by jawsvy12; 10-22-2019 at 12:56 AM. Reason: additional question

  7. #15
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    I got wiring diagrams from erwin.vw.com, though like I said, for this specific model, the VSS wiring is not 100% accurate in a single diagram. The 09A diagram shows what wire goes between TCM and ECU for VSS on gas engines, but on the ECU side it's a different pin on the 1.8T gas or VR6 vs. the BEW TDI. So, I had to use a MANUAL transmission BEW wiring diagram to find the correct pin and verify using a meter that my assumption was correct putting two and two together.

    Both TCM and ECU live under the wiper cowl, TCM being the one closest to the cabin filter, the ECU is smack in the middle.

    And yes, the tiptronic switch implausible signal is an issue with the board or the magnet on the gear selector inside the car. That is strictly for manual shifting control, should not affect cruise control and not seeing VSS in the ECU.

    Definitely strange that the MVB definitions I have say that bit is for clutch switch recognition when your car doesn't even have it. Something isn't adding up for sure.

    The brake switch should change xxxxxx00 to xxxxxx11. If those two don't switch to 1s at virtually the same time, that could be a brake switch issue as well, though generally, so long as they both read 0 when you're not touching the pedals, cruise should work. The brake switch is actually two switches in one. One directly signals the brake lights themselves, but also has the ECU monitoring that wire for proper electrical load (it will know if two brake light bulbs are burned out) and also checking switch plausibility by having a second signal that only goes to the ECU. And they operate opposite of eachother. So the switch that sends power to the brake lights themselves is open circuit when the pedal is released (and for reference, it's bit 0, xxxxxxx0) and the plausibility check switch is sending power when the pedal is not pressed (resulting in bit 1: xxxxxx0x). When the pedal is pressed, they flop. The brake light switch itself closes the circuit and sends power, the plausibility check switch opens the circuit, removing power from the pin going to the ECU for the plausibility check.

    So, looking at the other value in field 3, here's what we'd want to see:

    With cruise switched ON, bits 0 and 1 should be 1s (which they were in your log):

    xxxxxx11.

    When you press the SET button, you should see xxx1xx11

    When you press the RES button, you should see xx1xxx11

    At least making sure those are being recognized correctly.

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  9. #16
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    Also, for what it's worth, the Mk4 generation cars are the last ones to have VSS as its own separate set of wires going to modules individually.

    Starting with the Mk5s, the ABS module generates the VSS based on averaging the wheel speed sensors and broadcasting the VSS on the powertrain CAN bus for TCM and ECU to pick up as needed, and the CAN gateway can then also translate the VSS to the other two data buses as needed (for example, on the comfort system data bus so it can know when to tell the auto locks to engage at a specific speed).

  10. #17
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by dieseldub View Post
    Also, for what it's worth, the Mk4 generation cars are the last ones to have VSS as its own separate set of wires going to modules individually.

    Starting with the Mk5s, the ABS module generates the VSS based on averaging the wheel speed sensors and broadcasting the VSS on the powertrain CAN bus for TCM and ECU to pick up as needed, and the CAN gateway can then also translate the VSS to the other two data buses as needed (for example, on the comfort system data bus so it can know when to tell the auto locks to engage at a specific speed).
    I have a fuzzy recollection that there are some cars that could go either way. I.e. depending on how they were equipped, they had separate VSS, or they used the ABS. But I don' remember which cars this was applicable to.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

  11. #18
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    Quote Originally Posted by Uwe View Post
    I have a fuzzy recollection that there are some cars that could go either way. I.e. depending on how they were equipped, they had separate VSS, or they used the ABS. But I don' remember which cars this was applicable to.

    -Uwe-
    Mk4 era, they all definitely have a separate VSS. Even the DSG Beetle (also with BEW engine). Though what's interesting there is the Mech unit generates the VSS and sends it to the cluster, cluster then repeats it to ECU. I've wired one of those for a manual swap too... heh. Kept all the old parts because I keep thinking maybe I'll make a BEW Jetta wagon with a DSG or something. The bellhousing was cracked on the bottom from a DMF failure, but it seemed to operate fine and structurally still seemed OK enough. Just doing what the owner requested of me. heh

    If you're talking Audi, then I don't know. I haven't done near the extensive work or retrofits on them as I have PQ34 VWs. I have manual swapped dozens of 01Ms, a few 09As and the one DSG. Gotten pretty good and figuring out what to do about the VSS wiring... though in the case of the 01M, it's virtually wired the same as the manual, so that doesn't require much effort. Done both 5 and 6 speed swaps.

    The 6 speed definitely needs to have the cluster coded differently for different pulses/mile.

    Now, I HAVE noticed in optional coding in BEW Jetta/Golf and I believe even Beetle clusters that there does exist an option to obtain VSS via CAN (at least so says the coding aid built into VCDS). Now, whether or not those early Mk60 systems are actually broadcasting VSS on CAN or not is something I'm not sure of. Though I have considering experimenting the next time I do a BEW auto to manual swap, see if I could greatly simplify doing the VSS wiring by not having to wire it at all, just tell the cluster to pick up VSS from the data bus instead. But I can confirm that every one I've encountered has VSS still individually wired. It just appears that the cluster can support VSS via CAN but is not utilizing it.

    Now, even though I know mk5 (PQ35) EDC16s do pick up VSS from CAN, I'm unsure on if the EDC16 ECUs for the Mk4 does, or if maybe it can be coded to pick it up via CAN. Or maybe the cluster picks it up from CAN and I still just make sure I have the correct VSS output wire from the cluster to ECU.

    Someone send me a BEW they want to do a manual swap on. Let's experiment. lol

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