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ROVER 25 and a ROVER CABRIOLET
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Discussion Starter #1
The Mrs' coolant and its bottle are looking a bit rough on her new 25
so i'm going to swap the coolant and I was going to clean the bottle
out but I thought I would upgrade to a low coolant effort.

I had a low alarm kit for my old MGF that I have fitted to my Cabby
but I had to swap the bottle for a 25 unit, the sensors are the same
but the bottles mount differently but I don't have an alarm kit this
time, just wondering if there is a way to make up a kit ?

Could you just run a switched live through the sensor and wire it to
a light on the dash ?

Seems too simple but it cant take that much to make up can it ?
 

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other_manufacturer
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1,771 Posts
yeah just get a small bulb with holder (removable bulb type preferred ) pull out the bulb and either drill one large hole or 2 small ones at the bottom , pull out all the internals to the holder and trim off the bottom that the bulb usually plugs into power / ground to leave the top part that locks in to position straighten out the bulb wires and place threw drilled hole/s and wire up / soldier a connector on with a plug and a length of wire and run wire/s to coolant sensor and required power and earth ( make sure power one is switched with ignition ) ,place bulb in one of the empty slots and test ,and move to required place if required.
 

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2004 25 1.6
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45 Posts
I don't know whether old thread resurrection or start afresh is the preferred approach around here. I will go for the old thread approach as it seems more likely to come to the attention of those interested .....

Anyway a few weeks ago I got my £200 Rover 25 running, and last week I fitted a header tank from a later model that has the low coolant sensor. I have a couple of spade terminals and lengths of wire attached and that's it.

I don't like the look of getting a wire from the engine compartment into the cabin so I started to look at what's already there.

Pin 62 of connector C0913 looked promising as it's labelled "Instrument pack - engine bay overheat warning lamp".
It appears to pop out to the big connector that on top of the interior fuse box but probing there I found nothing, and shorting it to ground didn't make anything appear in the dash.

The next candidate was the engine warning (MIL) lamp. I found this wire on the same connector above the fuse box and found that warning light off it's at 12V and warning light on it's 0V. Shorting it to ground results in a pull through the short of approx 100mA and the light comes on.
This is expected because inspection of the wiring diagram suggests that the MIL is wired to ignition switched positive through fuse 25, and the engine ECU shorts the other side of the MIL to ground if it wants the light on. If the light is off then the ECU leaves it floating.

So from where I am now I am thinking that I will just wire one side of the switch in the header tank to chassic, and the other side to the MIL wire on the back of the ECU which is conveniently near to the header tank.

If the MIL comes on it means that either the coolant is low or there is an engine fault.

Anyone know any better?
 

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Rover Lifestyle
Rover 200 Rover 600
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12,587 Posts
Resurrection of old thread is not good option since members will start lloking from the first post and will be dissapointed when they come to yours. It is always better to start new thread.

Regarding lamps on the dash, you need to know that some lamps do not have bulb in place, so even if you managed to find out some wires which could light a lamp, bulb might be missing.

From my point of view, mixing two signals which do not have common topic is not a good idea. I think that you will be the first person to be in problem when MIL light goes on and you will not be sure for what reason. My preffered option is to use some of positions on the dash with missing bulb, put a diode instead of bulb and wire it additionaly. I dont mind having wires coming from engine compartmen to cabin, but gromet needs to be found and sealed properly.

But, as I said, this my view...
 

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2004 25 1.6
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45 Posts
ok point noted about old threads. Next time I'll start a new one.

Also I think that you are right and it's worth pulling the instruments to see what bulbs positions are unused. If the engine overheat position is there then that will be easy as it's already wired into the engine bay.
 

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2004 25 1.6
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45 Posts
I found that this wire


which appears to be the one that goes back to the ECU for the "engine bay overheat" warning connects to an empty bulb position in the cluster.
If one puts a torch behind this empty bulb position then this is what illuminates:-


other blank bulb positions appear to be:-
A red triangle (I guess a hazard warning indicator)
A seatbelt warning symbol
Glowplug warning light
A red light says "120km/h"

Anyway as the above second engine warning thing was unpopulated but wired back to the engine bay (I think), that's what I am going to use.
 

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2004 25 1.6
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45 Posts
Indeed. By the way normally ECU output drivers are "open collector", in other words a switch to ground. This is why the bulbs are connected to +12V on one side and the ECU earths the other side. So, if you short an ECU output to ground then the ECU won't normally care, but short it to +12V and the output driver could blow.
 

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2004 25 1.6
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45 Posts
It turns out that I was wrong.
The wire for that extra warning lamp goes from the cluster down to the connector above the interior fusebox, however the other side of the connector (so the cars main loom) has no wire, so it stops there.
At the ECU end of the loom there is also no wire going into pin 62.
So Rover designed in an "overheating warning lamp" from the ECU to the cluster, a special symbol etc, and then deleted the wire from the cars loom.

So I found a bung just below the expansion tank here:-


that comes out next to the Pektron here:-


I guess that this is for AC pipes or something (which I don't have).

From here I struggled for over an hour to run one of the wires along where the factory wiring goes over the top of the heater matrix. It was the only route that I was happy to use that won't get tangled in any moving parts like heater controls, clutch pedal or steering column, and from there it joins that un-used wire above the fuse box.

Test input:-


and result:-


:)
 

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'06 MG ZR +120 (HQM) '04 MG ZR 105 (IAB)
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The lamp position that you have illuminated in the first pic is the Engine Malfunction Indicator Lamp for diesel engined models only (which is why there is no bulb in it on a petrol model), so is certainly an available possibility.

I assume the same engine ECU is used for the MG TF as for the 25, and that would explain why there is an ECU connection for 'Engine Bay Overheat', as this feature is only used on the F/TF, so not surprising if it is not wired to the instrument binnacle on a 25 - the 25/ZR had no need for an engine bay overheat warning, and no warning lamp for such a function was provided in the instrument binnacle (the F/TF used a different binnacle design anyway).

You are correct that the large grommet you have found above the passenger footwell is where the air conditioning pipework enters the car on models so equipped.

Have you thought about the possibility of retro fitting an instrument binnacle from a facelift 25? It may be difficult to find one with the same or similar mileage to your 25, but it will have an low coolant warning lamp in place (immediately to the right of the handbrake/brake system warning lamp, instead of the hazard warning flasher indicator lamp, which was deleted from the facelift binnacle), and should be a straightforward replacement (provided you ensure it is one for a petrol car with the same fuel/brake system combination as yours - they are marked on the back as 'Petrol without ABS' or 'Petrol with ABS' (non-ABS cars took the speed signal from a transducer in the gearbox, whilst ABS equipped cars took a speed signal from the ABS system, and the two types are incompatible - you probably knew this anyway ;))

The lamp marked '120kph' was used for the legally required over speed warning required in certain markets. It wasn't used on UK models, but the symbol was still on the binnacle, but no bulb in it (not sure if it does anything on UK market cars if a bulb is fitted - I've never tried it).
 

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2004 25 1.6
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I had forgotten about the MGF / TF thing. I won't be changing the cluster. I just wanted something to tell me if the coolant is low before the engine is wrecked. I think that all cars should have this. The diesel engine warning light coming on if coolant is low achieves the objective and is good enough for me.
 

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ROVER 25 and a ROVER CABRIOLET
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Discussion Starter #13
I still havn't done this and the car has been scrapped now lol.

Great work on the un-used display, I added a red warning LED behind the heater symbol on my other 25 and I did the same on the low level fuel light too, looks factory.
 
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