HELP: Installing Electric Temperature Gauge in 1992 240

Discussion in 'Volvo 240' started by Fort Worth, Oct 6, 2003.

  1. Fort Worth

    Fort Worth Guest

    My engine temperature gauge on the dash of my 1992 240 does not work on a
    regular basis - in fact, I would be surprised if it's accurate even when it
    does work...

    I was advised by my local Volvo mechanic I should probably install a new
    temperature gauge, but it probably wouldn't be worth the expense to change
    the one out in the instrument panel if I just needed one for
    functionality...

    He did advise it would be electric so I could purchase a new one and just
    wire it into....

    That's my question. Where do I wire the thing? I looked through my Haynes
    manual but couldn't find much information about the temperature gauge. I
    pulled the instrument panel out to see if I could figure out where current
    one runs but I couldn't determine which connections were for the temperature
    gauge.

    I would like to get a small gauge and just install it on one of the empty
    squares by the radio.

    Any feedback would be appreciated. Any time I've needed help you all have
    always been very responsive and supportive. Thank you to all of the Volvo
    enthusiasts out there that make up this delightful group...

    Ray
    Fort Worth

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    Fort Worth, Oct 6, 2003
    #1
  2. Fort Worth

    Mike F Guest

    If you install a new gauge, it would be very unlikely to be compatible
    with the existing sender. The sender is under the intake manifold #3
    runner, look for the yellow wire.
     
    Mike F, Oct 6, 2003
    #2
  3. Fort Worth

    Fort Worth Guest

    Thanks Mike.

    I found the sender. Thank you for your feedback and your help.

    Do you know of a way to test the resistance in the sender to make sure it's
    working properly?
    Is there a way to remove or ground out the yellow wire to see how the
    existing temperature gauge responds?

    Thanks again...

    Ray

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    Fort Worth, Oct 6, 2003
    #3
  4. Larry McDonald, Oct 6, 2003
    #4
  5. Larry McDonald, Oct 6, 2003
    #5
  6. Fort Worth

    David Guest


    *That* explains why I noticed my temp gauge never ever ever swings high
    or low from the 9:00 position, even if the A/C is kicking on and off
    in hot weather.... So if it did actually start to move higher, how
    hot would the coolant temp be ?
     
    David, Oct 7, 2003
    #6
  7. Fort Worth

    Sean Nugent Guest

    I was in a Volvo specialist the other day where they were taking an
    engine out of an V70 that had cooked. Apparently the temperature guage
    moved rapidly upwards when one of the hoses blew off and dumped the
    water. The driver saw this and started to slow down but then the guage
    moved back downwards.

    They tell me that the ECU interpretes the temp reading and then
    displays it on the dash which is why it never moves. However, if it
    rises too high then the ECU can decide that the sender is faulty and
    just ignore it returning the guage to normal. Result - cooked head!!!!

    Sean
     
    Sean Nugent, Oct 7, 2003
    #7
  8. Sean Nugent wrote:

    Morons. Isn't the whole point of a temperature gauge to see the
    small fluxuations and alter your driving accordingly? Especially
    in an emergency situation like you posted, you WANT the gauge to show
    that it is climbing fast and not going down.

    That information would have been enough to save that engine.

    Funny, though - it would cost them less to make it the old way
    and it would be more reliable.
     
    Joseph Oberlander, Oct 7, 2003
    #8
  9. Fort Worth

    Bill Stehlin Guest

    As everyone has already pointed out, 240 temp gages are notorious for
    problems, but most (probably 98%) of the time it's the temp comp
    board, and that usually can be fixed just by cleaning the contacts.
    In over 20 years of driving 240s, and now have 4, have only replaced
    one temp gage, have replaced lots of temp comp boards (before I found
    out about cleaning), and for past several years have revived most just
    by cleaning and dielectric grease. If you do need to replace gage,
    used OEM are generally around $20. The test for the gage is easy and
    can be found in Bentley manual, which is a must for 240 owners.
     
    Bill Stehlin, Oct 7, 2003
    #9
  10. Fort Worth

    Mike F Guest

    Actually it costs more the old way, but for a totally different reason.
    The old way, people notice the small fluctuations, then complain to
    their dealer who just replaces some parts under warranty to make the
    person happy. This is paid for by Volvo. The new way, they don't
    notice the fluctuations, so they don't complain, and therefore Volvo
    doesn't have to pay anything.

    In this particular case, the check engine light should have come on with
    a temperature sensor code. Which goes to show you, if the check engine
    light comes on, it could be something not worth worrying about, or it
    could mean that your engine has 15 seconds to live!
     
    Mike F, Oct 7, 2003
    #10
  11. I think it's more a time/temperature thing, if it's running slightly hot for a long
    enough time, the comp board will allow the gauge to show it. This was done because so
    many folk will bring the car in for service if the needle is ever above it's "normal"
    spot, so the comp board lies about the current temperature. I've noticed, now that my
    car has the comp board yanked, that when I hit the freeway offramp and stop, the gauge
    will go up to about the 10:00 position for about 30 seconds before going back down.
    There must be some threshold, tho, 'cos my car was always rock solid at 9:00 with the
    comp board, and actually runs slightly higher than that normally with the board
    removed. On cold winter days the temps run at about the 8:00 position.

    Newer Fords with temp gauges don't even have analog senders. There are two temp
    switches on the engine, one that sends the gauge to the middle, and one that sends it
    into the red.

    The comp board's connections, as found on the 240, are really a work of crap. In my
    family there are five 240s ranging from an '86 to a '92, and they have all had comp
    board problems.

    When my mom's '86 was new, they and a couple of friends were driving across the desert
    when the comp board decided to act loopy and show an overheating condition. Since
    they were miles from anywhere, they opened the windows in 110 degree heat, cranked up
    the heater to help cool the car, and kept going. By the time they go to town, the
    70-something friend in the back seat suffered from heat stroke and they got to spend
    the rest of the day in the ER. Of course, nothing was actually wrong with the engine
    and we weren't yet aware that the temp gauge lies. This is why I prefer to remove and
    bypass the comp board rather than try and fix it, I'd much rather know what's going on
    now and not trust a device that's sole purpose is to lie.
     
    Larry McDonald, Oct 7, 2003
    #11
  12. Hi Fort,

    The board, as far as I know, never fails. It's always the contacts that do.

    However, I prefer to know what the temps are, so I jumpered my board out.
    As I recall, it takes two jumpers. If you can follow the traces on the back of
    the circuit board, it should be easy to figure out. I did publish on usenet
    about 15 years ago the pins to jump. :) Maybe google groups would still have
    it...

    Best,

    Larry
     
    Larry McDonald, Oct 16, 2003
    #12
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