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Temp gauge led coming on with blinkers

Discussion in 'T3 & T4 Tech Help Clinic' started by Kew, Mar 14, 2019.

  1. Kew

    Kew New Member

    Messages:
    12
    Location:
    Coffs Harbour
    Hi All,

    I'm new to the Kombi Club and my 1985 T3, and just did a little intro in the new members section.

    After driving around for a few days in Brisbane with no issues, I started to head home, south to Coffs Harbour.

    On the freeway after a couple of hours at 90km/h the temp gauge LED came on, and the needle rapidly rose all the way over.

    I immediately pulled over and inspected the coolant system: no leaks, expansion tank was full and overflow was midway. I measured the temp of the temp sensor at the thermostat housing and it read 80 deg C. The engine block read 70 deg C. Oil was fine.

    Suspecting the thermostat was faulty, I had the guys at Stokers VW Byron change the thermostat and waterpump. They pressure tested and inspected the coolant system and everything looked good.

    Carrying on down the highway for another hour, the same problem occurred - temp gauge went from sitting at 12 oclock to LED flashing and needle rapidly rising to max.

    Engine inspected again and temperatures taken with multimeter and everything look fine. This is when I started suspecting in may be electrical.

    I took off again later that day and then found that if I put the indicator on, the LED would start flashing and when the indicator was off, the LED would turn off. This happened several times before the LED stayed on for good again.

    I did the simple test someone recommended to test the temp gauge, by unplugging and grounding the temp gauge sender and the gauge at the dash seemed fine.

    I unplugged and the temp gauge sender and drove, and got the same result - LED flashing and needle from 0 - 100 very rapidly.

    Any advice on where to start looking for this one?

    Cheers,

    Kew
     
  2. Barry

    Barry Well-Known Member

    Messages:
    3,134
    Location:
    Abbotsford NSW
    I would be starting by looking at the blue foil in/on the instrument cluster.
    Known trouble maker and it is all up there together - leds, indicators etc

    Lift the plastic housing off from the windshield side and it is fairly obvious how it all comes out.
    Need to get your hand behind / under to disconnect the speedo cable

    Might just need reseating the connector?
     
  3. Kew

    Kew New Member

    Messages:
    12
    Location:
    Coffs Harbour
    Thanks Barry - ill get in there and have a poke around
     
  4. Grantus

    Grantus Well-Known Member

    Messages:
    15,114
    Location:
    Southern ACT
    As Barry said, and while you are in there, clean up the contacts on the 14 pin connector. ;)
     
    Barry likes this.
  5. syncro

    syncro Well-Known Member

    Messages:
    9,189
    Location:
    Southern Highlands
    Normally I would say it's the coolant level sensor but as it is flashing with the indicators I would be looking at an earthing problem around the dash area. Maybe in the foil or the earth tree near the fuse panel.
     
  6. Kew

    Kew New Member

    Messages:
    12
    Location:
    Coffs Harbour
    Looks like there has been a few repairs to the foil side of the 14 pin connector in the past - there’s evidence of a number of the strips being glued down. Certainly looks like an area that cause some troubles.

    I’ll look at the grounding today, cheers syncro.

    Any preference with the two alternatives I’ve seen for the foil - i.e. gowesty vs. Vanagon.org?
     
  7. Barry

    Barry Well-Known Member

    Messages:
    3,134
    Location:
    Abbotsford NSW
    Hmmm....... see if you can beg, borrow, steal a spare to check.
    Not cheap to go replacing with the hard wire kit
     
  8. Grantus

    Grantus Well-Known Member

    Messages:
    15,114
    Location:
    Southern ACT
    Last time I had the same symptoms, it was a faulty temp sensor, (which I note was your first thought and action), but then more recently, I had a new temp sensor fail.

    Only suggesting, as new parts are now sometimes faulty out of the box, perhaps fit another new sensor. Cheap and easy enough, and if it doesn’t sort the issue, one for the spares shelf. :rolleyes:

    Only heard good reports from the expensive GoWesty replacement. But as suggested, a borrowed known working one, would confirm whether the foil is faulty or not.
     
    David H likes this.
  9. Kew

    Kew New Member

    Messages:
    12
    Location:
    Coffs Harbour
    Thanks for the tips Barry and Grantus, I’ll see how I go getting a known working foil to continue the process of elimination.

    At least I’m getting an early familiarisation week with Bentley’s and the T3!

    I still have only seen the cool temp gauge needle and light flash and max out after 1 - 2 hrs of freeway driving (2 occurrences but once it happens it continues to happen) which is now steering me towards to coolant level sensor..?

    Anyway back into it today, some more diagnostics, and hit the freeway. The novelty of going for a spin is strong haha. Appreciate the pointers!
     
  10. Barry

    Barry Well-Known Member

    Messages:
    3,134
    Location:
    Abbotsford NSW
    There is someone Lucky Phil put me onto that does something similar to the GoWesty set up

    I will see if I can find the link
     
  11. syncro

    syncro Well-Known Member

    Messages:
    9,189
    Location:
    Southern Highlands
    Try cleaning the level sensor.

    What does your coolant look like?
     
  12. Kew

    Kew New Member

    Messages:
    12
    Location:
    Coffs Harbour
    Sensor is nice and clean, coolant is the right stuff, clean and was recently done too.

    The hunt continues...
     
  13. Kew

    Kew New Member

    Messages:
    12
    Location:
    Coffs Harbour
    Went for a run on the highway today and all seems ok now. Coolant temp climbed slightly above 12oclock but no warning light.

    I cleaned up all the earths near the fuses on the passenger side and the 14pin connector, thanks everyone for the pointers.

    Unfortunately I got caught in a downpour and am now idling roughly and stalling when trying to drive haha.

    Lots of info on this problem in various forums so I’ll dive in now!
     
  14. syncro

    syncro Well-Known Member

    Messages:
    9,189
    Location:
    Southern Highlands
    Check distributor cap.
     
    Syncro27 likes this.
  15. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    5,724
    Location:
    Gosford
    Agree 100% with Syncro, repla
    Agree 100% with Syncro, replace dizzy cap, while you are there prob good idea to replace rotor
     
  16. David H

    David H Well-Known Member

    Messages:
    3,955
    Location:
    newcastle
    Throw in some WD40 to dissy cap in humid conditions;).
    Cheers
     
  17. Grantus

    Grantus Well-Known Member

    Messages:
    15,114
    Location:
    Southern ACT
    Once the flashing light is triggered to come on, it will stay on until reset by turning off the ignition, even if it was triggered by low coolant, and you top it up, it will still flash until it’s reset. ;)

    I get a fake reading often when starting the SC, although the coolant level is full. When the needle leaves the cold zone, a quick ignition off, then back on, and it’s happy for the rest of the day. A bit annoying, and haven’t worked out why yet, but one of the idiosyncrasies of that vehicle.

    Luckily, it still gives a true low coolant flash after distance, if it really is lacking 100mls or more of coolant.

    Probably worth pointing out, with the VW electrickery design, the flashing light has two triggers to come on. 1, if the coolant pressure bottle is a bit low, even if the operating temp is normal, and 2, if it detects a serious temperature rise. ;)
     
  18. syncro

    syncro Well-Known Member

    Messages:
    9,189
    Location:
    Southern Highlands
    Better off fixing it properly and buying a decent brand cap.
     
  19. Kew

    Kew New Member

    Messages:
    12
    Location:
    Coffs Harbour
    Turned out to be water in the fuel from a cracked expansion tank on the passenger side. The crack wasn't visible until it was removed as it was on the inside. Possibly dodgy fuel adding to the equation - as I had just filled up from a little, low traffic servo that apparently has a bad reputation for bad fuel!

    The valve on the top of the tank is pretty old and haggard looking too - might have been some water getting in there too...

    Do you guys normally start a new thread if the conversation deviates to a new topic?
     
  20. syncro

    syncro Well-Known Member

    Messages:
    9,189
    Location:
    Southern Highlands
    Tech Tip; Do not fill up from a little, low traffic servo that apparently has a bad reputation for bad fuel! (or Caltex)
     

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