Thread: Gearbox temperature gauge

If the sender is the same type, I would. However, how can you be sure that the new gauge has the same kind of sensor though?
Is this a manual or auto vehicle? I have never heard of manual gearbox temperatures being an issue.

Good luck.

I’ve got a WatchDog TM4 fitted....is your similar to this

What temp does your gearbox get to??

cheapo ebay gauge/sender unit? but which one? Or more specifically, does it work like a std VDO type sensor that uses resistance as the data measure, or does it use a temperature sensor type thing that we couldn't possibly help diagnose?

Reason I ask is that if it's a std type sensor that uses resistance as the data path, then there is a likelyhood that the connection at the sensor is loose .. just enough to cause higher than standard resisitance!
Had this same issue with my VDO coolant sensor. I have it mounted high up on the bleeder nut, so it rubs ever so slightly on the bonnet insulation. Not much, just a whisker.
Originally I had a standard spade connector on the single wire from the sensor to the gauge unit.
That was the actual issue, being just a std spade connector, it'd come loose every so often. When loose, coolant temp would spike up quickly from say 80, to well over 100 or more!
First time around, it scared all the brown stuff out of me too!
After some looking around, it was obvious what the issue was, gave the (female)spade connector a bit of a squish by hand, and back on the sensor .. no problems!
So I eventually found the proper lock on spade connectors used for sensors, along with the usual black plastic protector covers, these ones have a small tab on the spade that locks onto the male spade terminal on the sensor.
No issues since.

So before you go chasing up a complicated solution to what may be a very simple fix .. check the connector on the sensor for fit and tightness.

Also, adding to what Milton said, sensor and gauge need to be 'paired', or at least in sync.

eg. in the VDO range you can get a 40-120°C sensor, which NEEDs to be connected to a 40-120°C gauge. If you use a 50-150°C sensor or gauge with the wrong 'other end' it obviously won't read the correct value.
They work on resistance and need to be matched up.

Thanks for the replies- I can't use thanks button on my phone - it's a digital 52mm guage that I'm sure uses an electrical connection but I don't know what range
It's been reading 60's across the Nullabor but mild weather. It got to low 90's earlier in the Flinders but then went kinda crazy after that, so I was going to buy a new one in Norseman or Esperance. I might just have to swap out the sender too. Thanks for the advice..- BTW we just met another Defender in the most remote track heading to Twilight cove south of Cocklebiddy -small world. David

i would add one of the electric watchdog temp alarms onto the motor and gearbox, they are great and give you a digital readout.
you normally have to use what ever sensor that comes with the guage to get a correct reading.
The other idea is to get an infra red temperature reader.
These are now very cheap from 40 bucks upwards and you can check the temp of lots of other items on your vehicle as well, great for tyres and wheel bearings , radiators , the missus and anything you can think of.

Ian
Bittern

It depends on the output of resistance and how the receiver interprets it. With the madman system you can for instance calibrate a curve or linear line. Vdo has a black and green temp sender with different outputs. The gauge shop in new castle can perhaps help you.