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Anyone here successfully retrofit a Coolant LEVEL sensor?

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46K views 61 replies 19 participants last post by  bluebee  
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#1 · (Edited)
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#2 ·
I have the Low OBC, so this is my plan: I want to connect the Coolant Level Sensor into the "Low Windshield Washer Fluid" circuit as a practical solution.

It is kind of a "******* engineering" but this allows me to see some warning such as "Low Windshield Washer Fluid", this warns me to open the hood and check for BOTH coolant and washer fluid levels anyway.

Anyone has tried it this way (tapping into the Windshield Washer Fluid sensor circuit)?
 
R
#3 · (Edited)
I tried to find a solution to this problem, i.e. the low cluster does not have a coolant level warning. I wanted to connnect a retrofit level sensor in the expansion tank, connect it to the LCM which was then supposed to control the (inactive) "low radiator" mask in my low cluster. I got lots of help in the bimmerforums/diagnostic forum, but failed. My last post follows.

*********************
I've hunted high & low for coding to implement the low coolant light in the low cluster. I've not even been able to confirm that it is feasible, i.e. that VDO/BMW implemented the feature. I'm conceding defeat on this approach.

I have though, worked out a solution to put a light and buzzer into the cluster cutout for the tire pressure monitor switch. It's fairly simple: the stock tank level switch, relays, small pilot light, 12V buzzer and a button switch to turn off the buzzer, heaven forbid it would be needed :) . The concept works but I'm waiting for warmer weather to install. I'm leary of taking apart all the plastic bits needed to run a circuit from the radiator through the firewall up to the cluster in these freezing temperatures. Not to mention frost bitten fingers - unheated garage.

I'd post schematics, but don't see how to insert a file. How does one do that?

I'll do a DIY when I Mother Nature co-operates.

Regards
RDL
***********************
I later figured out how to post images of the wiring diagrams. Here they are.

EDIT: note that the relays showing have snubber diodes indicated. I added those since I found really a great deal on non-protected relays. If you don't have this protections, the relay coils can generate voltage spikes up to 100 V - not good for the electronic modules. BMW uses resistors rather than diodes - a good solution too, except I could find the correct ohms. Nor could I find BMW NC relays that my design needs.
I also have a concern that the buzzer may create interference and interfer with the various control & information busses when it is activated by a low level condition. The electronics supply house assured me not, but I will need to check with an oscilloscope once installed.

Hope this helps

RDL
 

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#4 ·
Some more thoughts.

I've attached a picture of my cluster with the icon/mask I hoped to activate. Yours may have the same mask available.

I based my original plan on the routing and pin-outs in high cluster retrofit instruction, copy attached. Without, the retrofit harness thought, just the connection from level sensor to the LCM.

I couldn't make the low rad icon light up inspite of repeated attempts in INPA and DIS with the "activate" and "cluster test" functions. But, I have a quirk in my LCM. It reports to INPA and NCS Expert as coding index 6. Yet, Revtor (NCS Dummy author) worked out that when reading the LCM it reported parameters for coding index 7 that are not in coding index 6. Revtor couldn't understand why. He'd never run into this condition.

Perhaps this quirk in car explains my lack of success. You might succeed.

Regards
RDL
 
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#7 ·
Thanks RDL,

I will do some research on the Windshield Washer Fluid Level circuit and prefer to tap to that circuit for simplicity reasons.
This way when that dash light is ON, I simply open to hood to check for either coolant and/or windshield fluid levels.
Some warning is better than no warning!
 
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#8 ·
I couldn't agree more that some warning is better than none. And your idea will certainly give you a warning.

FYI, the sensor, connector & terminal parts for my '03 530i, with the black expansion tank are:
Level sensor 61318360876 qty 1
Universal socket housing 61138365340 qty 1
Bushing contact 61130005199 qty 2

The bushing contacts are the metalic terminals you assemble into the socket housing that plugs into the sensor. They come with leads about 18" long already attached.

Luckily, both switches are closed when level is good, which grounds the circuit from the LCM. It should be relatively easy to wire them in series. My coolant level sensor returns 0.2 ohms when closed. If the washer level sensor is the same there should be no trouble with the LCM seeing a good enough ground to not light the cluster warning when levels are both good.

Regards
RDL
 
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#9 ·
cn90 said:
Hi guys,

I forgot which year they introduced the Coolant LEVEL sensor (maybe 1999 or so) but my car does not have one. So I want to install it but reading some old posts, it seemed like people have problem installing it for a variety of reasons.
Click to expand...
I think it is more a function of high vs low cluster not year.

I've got a 11/97 build date with a coolant sensor on a high cluster.
 
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#10 ·
Yes, your correct about high vs low cluster and sensor being installed.

The high cluster retrofit instruction from BMW states:
"The expansion tank must be replaced on cars with M51 engines built before 01/99."

Regards
RDL
 
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#14 ·
GSA1, rdl,
Thank you, thank you, thank you!!!
It saved my day!

Now I know exactly what to do. This circuit is complete opposite of the oil pressure sensor:
- Windshield Fluid Level sensor: Full ---> circuit closed ---> continuity of electrical circuit
- Oil Pressure sensor: Good P ---> circuit opened.

Anyway, I will wire the coolant level sensor in series (not parallel) with the Windshield Fluid Level sensor.
It is too cold now, so this project will have to wait a bit!
 
#15 ·
It'd certainly be nice for this to work...
 
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#16 ·
#18 ·
cn90 said:
I already have the sensor
Click to expand...
OK. Luckily, this is something that can wait until you get a round tuit.
If you need a spare when you attack the problem, then let me know.

BTW, it seems the magnetic disk embedded in the float merely wraps around a bulb in the electrical level sensor, somehow causing a circuit to close (or is it open? Probably not.).

Are you mechanically going to try to reproduce that magnetic-switch mechanism?
 
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#24 · (Edited)
16valex is absolutely correct,

Any of these 2 sensors (windshield fluid or my proposed coolant level sensor mod) is tripped, the dash light is on.

Consider myself lucky, my car has low OBC so no "Low Coolant Warning Light". I was pulling the car out of driveway and saw a small puddle of coolant.
I stopped the engine. Removed Fan Clutch etc.
Initially thought the leak was from Water Pump because I saw coolant under the WP. I was about to remove the WP but then saw coolant dropping from above onto the WP at a rate of 1 drop per 15 seconds!
A quick mirror check revealed that the leak is in fact from the Tstat housing.
Lucky I was patient and looked around first.

Accurate diagnosis = accurate fix.
Wrong diagnosis = wrong fix so to speak.
Went to dealer and got 2 new seals for Tstat (my Tstat housing is only 20K miles old).
Now it is bone-dry but I force myself now to open the hood at every gas fill-up to check all fluids!

This is my proposed plan. I don't have time to do this yet. It is too cold in my garage with Nebraska winter, but will report back in the Spring when I have time to tackle this:

Image


Jason,

By the time one sees steam under the hood, I think it may be too late, we are now talking about $3-4K fix!!!
 

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#25 ·
I just did some more research and this is what I have so far:

- I "borrowed" picture from the internet to show the cluster. So the pic below is not mine but anyway, I have the Coolant Level "Icon" already, but it seems there is no bulb under that Icon.

- In the engine compartment, there is an "Empty" connector near the Coolant Reservoir.

So this whole thing may be much easier than I thought. I am thinking connecting the Coolant Level Sensor into the "Empty" connector and install a bulb into the empty spot in the dash cluster. What do you think?

Image
 

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#27 ·
What car is this cluster from?? I have a 2000 528 with the low OBC and it's different. I have a "SERVICE ENGINE SOON" light and my MPG gauge thing goes up to 40, not 50. I'm sure for the purpose of this post that picture may do justice... but I wonder since it is a little different, maybe your cluster already has a light already there... it's just not activated.
 
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#26 ·
Doesn't look like there's a light there. I wonder if it's possible via coding and some soldering to do an "OEM" retrofit.

VDO (or whoever built the cluster) certainly intended to have a low coolant warning light. It's idiocy that there isn't one.The low coolant can result in an overheat without notifying the driver, as the coolant may not circulate.
 
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#29 ·
I looked for a while, couldn't find that thread. Thanks for posting it.

I haven't heard of any market in which the light worked (not that it comes up in posting much) but it seems incredible that the light is there, the LCM supports it (through I-bus at least) and doesn't work in the low cluster. Perhaps Siemens (iirc who built the LCM) blanked out on it and didn't have enough time to add it to the K-Bus code... and never added it to the low OBC cars? It is pretty odd.
 
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#30 ·
I tried to find that thread but I couldn't. Thanks for posting the link

I do find it odd that it's never been mentioned as working in any of the African or Japanese cars (which might have had special equipment, Euro/NA cars didn't have it certainly). I wonder if Siemens left the coding out of the LCM, only for K-bus or VDO left it out of the cluster, somehow, and it was never added in later cars. It's a very odd omission.
 
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S
#32 ·
I think this is a meaningful and useful upgrade to pursue. I installed a coolant level sensor on my car and it has already come in handy. When I hit the deer, I did an initial assessment of the car and did not notice any damage to the radiator. A few days later I must have developed a leak in the radiator and sure enough my low coolant light came on for the first time. This led me to the discover part of the fog light was lodged on my radiator.

That said, I reviewed my wiring diagrams and it appears you maybe able to get the coolant level warning light to work. First thing verify that PIN # 24 on the black connector on the LCM is occupied. This is the pin that needs to be connected to the coolant level switch.

I doubt any coding needs to be done. I did not have to code anything for the level switch to work in my car.

If all else fails, the windshield washer idea will work.....just have to make sure your washer fluid is always topped up :)
 
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#33 ·
Schitzo said:
....That said, I reviewed my wiring diagrams and it appears you maybe able to get the coolant level warning light to work. First thing verify that PIN # 24 on the black connector on the LCM is occupied. This is the pin that needs to be connected to the coolant level switch.

I doubt any coding needs to be done. I did not have to code anything for the level switch to work in my car.

If all else fails, the windshield washer idea will work.....just have to make sure your washer fluid is always topped up :)
Click to expand...
Hi Schitzo,

Could you post exact detail:
- PN
- Pin#24 LCM
- What to do at the Cluster: just install a bulb and that is it?
- ? No coding of LCM?
 
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#37 ·
My car has a "Icon" which I am not sure what it is.
I call it "Coolant Level Icon" but after all this may be the Washer Level Sensor.
My owners manual says nothing about this light (Orange Arrow).

Does anyone know for sure:
- What this icon (Orange Arrow) means?
- And does low cluster has a windshield washer warning bulb?
 
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#38 ·
Now it is clear to me that:

- The "Orange Arrow" points to the Coolant Level sensor, which is an empty space in my cluster. Probably difficult to retrofit this way as my LCM may not support this function of "Coolant Level sensor". I have not checked my LCM's pin #24 yet (no time yet!).

- The "Low Windshield Washer" message is in the form of Text message and not a bulb.
 
O
#40 ·
CN90, please post diy when you do this. The new expansion tank I put on came with a sensor and I would like to make use of it. The use of the windshield washer circuit seems to be a very logical solution.
 
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