MG LE500 speedometer in TF - wrong coolant temperature gauge

hello,

last year I bought a MGTF built in 2002/03 (vin 6045524). The seller had already bought an MG LE500 speedometer from cowaparts, which I also received. I installed the speedometer with the correct cable over the weekend, but unfortunately something doesn't seem to be working with the coolant temperature gauge. I made a video of it and attached it. I had no problems with the coolant temperature display with the old speedometer. so, what could be the problem?

(I hope I wrote it in a way that you can understand because I come from Germany)

btw - great forum


Video on gmail

The dashboard does not recognise the input from the temperature sensor. It is best to check if a different type of temperature sender was fitted to the LE500.

Although the Chinese built LE500 is closely based on the British made TF there are some differences. Bear in mind that the N series engine in the LE500 is not quite the same as the British made K series; it is very likely that sensors will be different between the 2 cars so you will need the later sensor.

The water temp sensors are the same on later UK TF as the Chinese TF (both water temp ECU and Water Gauge senders) The Chinese temperature gauge lights up one segment after another and three steady lights are 'normal' temperature.

Never seen that happen on mine but my best guess is it is in maybe some sort of test mode, or it is open circuit and it is searching for a signal. Cheapest thing to change is the blue water temperature transducer.

If you want to check the transducer is working it should give 3.25v @ 20c, 2.5v @ 50c and 1.15v @ 80c

By the way, many things on the Chinese MGTF that are different were actually designed by Rover before the collapse and sale to SAIC, the "new" dashboard was one of those things. Rover could not afford to implement them in Project Drive. It was designed to work with the existing sensors.

Cheers, Mark

Thanks for the advice. is this the senor to be replaced?

water temperature transducer YCB100420

Yes, that's the one for the temp gauge. When you take the engine cover off , looking from back of car it is top left rear of engine. There are 2 sensors going to same water union. Brown is for ECU and Blue is for Temp Gauge. It's the bottom one pointing down.

If you are quick you will loose very little water so no need to bleed system. Have replacement ready, remove old one by hand when loose and as you pull it out, put finger of other hand over hole. Swap sensor over , line up, pull finger out and screw new sensor in by hand. I only lost about 20cc of water.

Before you start make sure you depressurise the cooling system before you start, be removing the cap from the header tank, thenr replace it.
Even when cooled there can be minor residual pressure, it’s just so you loose less coolant