Low Coolant Level Sensor

I am currently looking at fitting an external sensor to the header tank, I think I have found a suitable inductive level sensing device that should work, which means I will be able to use my existing tank without having to cut any holes in it.
The sensor should sense when the level drops to 20mm below the centre seam of the tank, which should give me plenty of scope for fluid movement on bumps and gradients.
Will post more when I have fitted and tested the unit.

Sundance

My TF135 has VIN 637249 and was first registered Mar 2005. The assembly date was 6/9/2004 and it was fitted with low level coolant alarm. The float had disappeared completely from the tank so I bought a new tank and reconnected original sensor and it has worked fine since. Around that period it is very much hit and miss what you actually got as, according to Roger Parker's book, cost saving measures were introduced from end of 2002 to end of 2004

Thanks for that info. My VIN is 634712 so I guess it's a little older than yours.
Since starting this post I now know the plug I identified is in fact on the end of a longer wire that comes out of the wiring loom around the centre of the engine bay and it has been tied off to hold it out of the way.
So I believe I do have the correct wiring in place. I assume that at some time the original coolant tank has been replaced with a standard tank.
Before I shell out the best part of 70 quid I need to be sure that my wiring will work but I suspect it will be a case of buy and hope for the best.

Hi Bob
My TF 135 was built 11/06/04 vin no RDWBKC5D634253 .It has the wiring for the sensor,a square black conector.It was cable tied to the back bulkhead by the expansion bottle.I bought a new bottle with sensor and it all works fine.The low level warning light did come on with the ignition and went off after a few seconds before I fitted the new bottle.I thought that it had the level sensor already fitted.The car was built with a tank without the sensor.
I would check the bulb in the dash,if it works just cut some of the cable ties holding the cable to the bulkhead,fit a new tank with sensor and Bob's your uncle
(excuses the pun):woohoo:

That's very encouraging and I think I will take the plunge.
The warning light on the instrument panel does not light up although I believe it does work as it has flickered briefly when the wipers have been on.
As you suggest, the bulb might need changing - there's only one way to find out.
Bob

Hopefully the last question on this topic.
Which light on the instrument panel should light up when the sensor etc is installed, after switching on?
Bob

Hi Bob Its the 2nd one down on the right hand side.Picture below

Many thanks for that info and for the link.
I thought that warning light was the one. I'm waiting for delivery of the new tank and sensor and the info on the link will be very useful for pretesting, before I do the swap.
As always, great knowledge shared between MG'ers.
Bob

PS: I will update the thread after I have installed the new tank and sensor.

I should have known nothing would be straight forward.
The new tank arrived, I connected up the plugs, and tested as suggested before replacing the new tank for the old one.
Absolutely nothing happened, no warning light lit up at ignition switch on or engine running.
That makes me believe there are 3 possibles scenarios:
1. I have got a duff tank (unlikely as it is brand new)
2. There is a fuse or relay somewhere in the circuitry that needs fitting
3. The bulb in the instrument panel is either not there or has blown.

So, does anyone know if there is a fuse or relay that I can check and, if the bulb has blown/gone, how do you go about replacing it?

I have had a look round the How To section but can't actually spot a step by step guide. What I have found looks fiendishly complicated to change a bulb.

Any suggestions will be gratefully received.

Bob

If you have a multi meter check if there is a supply to the plug, I think the switch just grounds the the negative supply so you to find a known positive and check between both side of the plug to 12v and vise versa.

Take the plug off the bottom of the float/reed switch on the underside of the header tank and bridge the 2 connections, switch on the ignition; 30 seconds or so the warning light should come on.

If this light illuminates, then plug into the reed switch and do the same. Ensure that the float is in its down position before switching on the ignition.

Thanks for the advice.
I don't have a multimeter so that one's out.
I tried bridging the plug, waited for about a minute and nothing happened.

Do you think it likely that MG would have put the components in the wiring loom and not carried this through to the instrument panel?

Any other ideas for me to try.

If not I think it will be time to give up and go for an after market solution.