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    Thread: Can the voltage regulator in gauge cluster be defective if the digital temperature works?

    1. 06-25-2008 03:52 PM #1
      My 95 Corrado has a temperature gauge that gets up to about 70-80C's when I turn on the ignition, the fuel gauge stays at 0.

      I have read around and found that it might be the voltage regulator, however the temperature on the MFA is working, so before I solder in a new voltage regulator I'd just thought I should check if it can be faulty even if the digital temperature is working.

      If not, any other tips on what's wrong are welcome...


    2. 06-25-2008 04:42 PM #2
      If there is anyone who have tips on what else it could be it would be great, as I just did a check of the voltage regulator itselfe.

      Input: Aprox 12V (ignition on).
      Output: Aprox 9.99V.

      So I guess it's functioning properly ?...


    3. Member sdezego's Avatar
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      06-25-2008 04:50 PM #3
      What exactly is workign and not working? The temp gauge on the MFA has nothing to do with the Voltage regulator iirc.

      If the Coolant gauge AND the fuel gauge are both not working or are both inacurate, then it can be the voltage regulator. The output voltage should be 9.5-10.5 volts, so it sounds like you are within specs unless it is intermittent.

      Is you coolant gauge working at all?

      Is your Fuel gauge working at all?

      Speedo work?


    4. 06-25-2008 05:13 PM #4
      Speedo works fine, also RPM works fine, and MFA works fine.

      But when I put the ignition on it will put the temp-gauge to aprox 70-80C's and the fuel gauge will stay at 0, so these 2 gauges doesn't seem to be working properly....


    5. Member sdezego's Avatar
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      06-25-2008 05:28 PM #5
      sounds like it certainly could be the Voltage regulator as those are the symptoms of a bad one (one one that is not putting out enough voltage).

      You can get the regulator type off the the package (LM2940T) and order it from Digikey.com or mouser.com (should only be a couple of bucks). The factory one is riveted to the heat spreader, so you will need to carefully drill the rivet head off first. You could probably use a small screw and nut to but it back (nut on top). This would require you to desolder the heat spreader stantions first, bolt the reg to the spreader (properly bending the reg's pins first, then slip it onto the PCB and solder the stantions and then the regulator pins.

      G/L and let us know how you make out.

      Shawn


    6. 06-25-2008 05:31 PM #6
      ok, guess it still can be f'ed then even if it measures ok?.....I'l get around to ordering a new one soon.

      btw, any chance it can be the temp/fuel cluster itselfe that's erroring?....


      thnx again for the reply...


    7. Member sdezego's Avatar
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      06-25-2008 05:59 PM #7
      doubtful. Even though they are on the same physical module, they are two separate gauges.

    8. 06-25-2008 06:04 PM #8
      ok, thnx for the input.

      btw, you happen to have any idea if I could connect a gauge cluster from my Passat VR6 (a bit older, and it's a "motometer" cluster, and VDO in the Corrado), just to check it.......or does it have other differences too ?


    9. Member sdezego's Avatar
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      06-25-2008 10:07 PM #9
      I am pretty sure it would work even being a motometer. VW did not mix match the wiring on the cluster plug. I can't guarantee it, but I am 99% sure.

      ..as long as it is a digital cluster (mileage) which I am assuming it is since it is a Motometer.


    10. 06-26-2008 06:06 AM #10
      sure did work, however the temp gauge still seem to ba failing, going up to 80-90 C's, but the fuel gauge worked on this one.

      Could it be something else that's malfunctioning then the voltage regulator on the corrado cluster?


    11. Member sdezego's Avatar
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      06-26-2008 08:30 AM #11
      I have found that in the the different generation clusters, the temp gauge senders are different (i.e. the resistance curves). For instance, I tried to use a later type coolant sender in my Corrado, and as the engine started to warm, the gauge would skyrocket. Had to switch to the ABA, 4 pin which is correct for the gauge generation.

      Not sure if that is the cause or not in your case, but would be suspect. Are you sure your CTS is good?


    12. 06-26-2008 08:40 AM #12
      CST meaning soldering or?.

      I'm gona try to "bend" the "clips" that the gauge itselfe gets connection from on the Corrado cluster to see if that might help.

      According to the bentley manual my voltage regulator is within spec of that it's suppose to do......

      The motometer cluster is older then the one in the Corrado (1991), but see it also have a vacume hose connected to it, no idea what that does, but sure it can be some differences between the clusters.

      Any idea if the temp sensor for the temp gauge would throw an error on VAG-COM?

      (as I have no errors).....


    13. Member sdezego's Avatar
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      06-26-2008 08:49 AM #13
      CTS = Coolant temp sensor (the one for the temp gauge in the cluster, not the one for the ECU).

      I would make sure it is it working and in proper spec. There is a resistance curve in the Bentley you could check against.

      The Motometer has a MAP sensor just like the pre 93 clusters. Used to measure engine vacuum for MPG calculations.


      Modified by sdezego at 8:50 AM 6-26-2008


    14. 06-26-2008 08:53 AM #14
      Ok, will do, happen to have any tip on how to remove the plastic cover that's over the temp gauge sensors?

      I presume it's the black one besides the blue one?


    15. Member sdezego's Avatar
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      06-26-2008 09:36 AM #15
      Quote, originally posted by Mawrick »
      Ok, will do, happen to have any tip on how to remove the plastic cover that's over the temp gauge sensors?

      I presume it's the black one besides the blue one?

      You can take the plastic plug right off of the sensor to measure (squeeze those wire clips together and it should unplug).

      Yes, Blue should be for the ECU, Brown for the A/C and such and the other should be for the Temp gauge and Fan Control unit.

      I think it should be a yellow 4 pin sensor plug and I thought the sensor was yellow too?? Maybe you have the wrong one in there? The Blue/white wire should be the pin for the gauge (and the brown directly across from it).

      (pins 2 and 3) if you look real closely on the plug (tiny lettering).

      Here is a pic -> http://www.wgcinc.com/sd/shawn...5.jpg

      Shawn


    16. 06-26-2008 03:09 PM #16
      yea, it might be yellow, haven't gotten to look at it yet, (just some mentioned that it was black on the G60's, so presumed it was the same... ).

      But there is a plastic cover covering all the sensors, any idea on how to remove that without damaging it?.


    17. 06-26-2008 05:37 PM #17
      Just tested the Corrado gauge in the Passat, and it seem to me that the temperature is working, so I guess the corrado temp-sensor is bad.

      However the fuel gauge doesn't seem to operate at all, so I guess that part of the gauge has gone bad.

      Also tried to ohm the gauge, the temp gauge is about 50Ohm, but the fuel gauge seem to have a very high ohm value.

      Is it possible to buy these gauges loose ?

      And if you know how that plastic cover over the temp sensor works, feel free to put in a tip about it.......remove it without breaking it...

      regards


    18. Member sdezego's Avatar
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      06-26-2008 08:28 PM #18
      Quote, originally posted by Mawrick »

      And if you know how that plastic cover over the temp sensor works, feel free to put in a tip about it.......remove it without breaking it...

      regards

      Ping the two metal wire clips on each side of the connector and pull. It will come right off the sensor.

      The temp and fuel gauges senders will have waaay different resistances. The Fuel gauge resistance from the sender should be between 50 and 350ohms iirc. You can try grounding out the fuel sender to see if the gauge goes up to full, but it requires:

      - lifting the trunk carpet
      - removing the three sheet metal screws over the round fuel pump access panel
      - unplug the connector on the fuel pump
      - connect the fuel gauge sender wire to ground and the fuel gauge should peg fuel with the key on

      The key has to be on and make sure you don;t ground out the +12v fuel pump lead.

      If the gauge didn't work in the passat though, I would presume there is something screwed with the gauge itself. I have experienced, unpluging and re-plugging in the gauges to help issues on occasion.

      G/L

      Shawn


    19. 06-27-2008 02:21 AM #19
      yea, I guess the gauge is f**, I have had it in and out of the cluster itselfe a couple of times so doesn't seem to respond.

      It's not the sensor itselfe I'm not sure how to remove, but there is a plastic cover, covering all 3 sensors, wich I'm not sure how it's "clipped" on.....just thought I should figure that out before I break it....


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