Water Temp Gauge Not Working...

Discussion in 'Fox 5.0 Mustang Tech' started by GreatWhite, Sep 7, 2013.

  1. As many people have expressed like a thousand times over, the stock temp gauge in my 89 LX has stopped working -- it just hangs in the bottom-most cold position regardless of how hot it gets.

    Replaced the sending unit. Nothing.

    Disconnected and grounded the pigtail, and the gauge went up to full hot (as I'm told it should). Nothing once reconnected.

    Replaced sending unit again ... Still nothing at all.

    It's more annoying than anything else because I can't figure out why it won't work at all.

    Advice? Aside from the obvious "get aftermarket gauges..."

  2. Are you using a ton of teflon tape or dope on the threads? That can interfere with the sender's ability to ground. If you want, ohm the sender body out to ground, or just alligator clip a temporary ground wire to the sender body (away from the gauge's wire connection) to see if it affects the reading.
  3. I will try that. It was just replaced the second time at the mechanic this past weekend when I went in for PA inspection.
  4. While it could have potential to cause other problems too, check the engine ground strap.
  5. As simple as this sounds make sure the pigtail connector is making a solid connecti0n on the sending unit. After 20+ years of on and off, it may be loose and not giving a good signal. Also be careful of grounding out that sending wire too long, as it will fry the gauge.
  6. To add to Mikestang63's post, you could check the resistance at the sender (where the gauge wire attaches to the sender) on a cold engine. Then on a hot engine. If the readings are quite different but the gauge isn't moving much, that at least tells you the sender ostensibly functions and that the issue is downstream.