Dashboard coolant temperature gauge not working

Technical Area Electrics & ICE
1
  1. My model of MX-5 is: NB 1999 BP4W
  2. I’m based near: Slough
  3. I’m looking for technical help or recommendations on: The coolant temperature gauge in the dashboard is not working. I know it’s the gauge and not the sender because the car has a ME442 aftermarket ECU and I can watch the temperature change in the PC interface, also the cooling fan is going on and off at the correct temperature. Does anyone have any idea what could be wrong and, if the gauge is faulty, what is the possibility of replacing it - it looks like the dash is a single unit and not separate instruments.

Thanks

John

2

The instrument cluster does come apart to enable changing individual gauges. Depending on how handy you are, you may want to do some other tests before chucking parts at it though.

3

Thanks Robbie, do you know where I can buy a new gauge?

Thanks

John

4

If you want a new gauge then you’re probably limited to a Mazda dealer. It’s probably more cost effective to buy a complete used instrument cluster from eBay and use the gauge from that.

5

The fans are triggered by the sensor at the front of the engine. The gauge receives a signal from the sensor at the back near the bulkhead. I’m not sure which sends information to the me442 but you could try unplugging one of them to see what happens to the temp signal in the ecu.

6

Thanks for your input Jacob, however this car, a 1999 MK2 1.8 definitely has only one temperature sensor and it’s at the back of the engine. I know there isn’t one at the front because I have fitted the BOFI coolant reroute kit and there was no sensor at the front. I have the factory wiring diagram and it only show one sensor at the back of the engine.

Thanks

John

7

Thanks Robbie, I may just fit an aftermarket gauge in the dash.