IHKA/AUX WATER PUMP
 

Some months ago the aux water pump stopped working. Ignored it cos it was summer, have now fitted new one which puts coolant into header tank but at about 25% flow. Checked voltage at plug and it’s 4.65v Put 12v to motor and it runs like a trooper. Question does the IHKA regulate the voltage or is it faulty. Never seen more than a trickle all the times I’ve looked. Have put a separate earth to the plug without any improvement. Thanks in advance.


Sent from my iPad using Xoutpost.com

Sounds strange. There should be direct battery voltage from IHKA to aux water pump when activated.

the low voltage is really a problem. it could be a relay or transistor driver that went bad. do you have access to the wiring diagrams ?

There are no relays. It must be a FET on IHKA board.

https://www.newtis.info/tisv2/a/en/e...r-pump/hDKLnGe

I thought I saw my foxwell had a test setting for 30% etc speed. I have a feeling you are seeing a PWM reduced speed on purpose.

If the heater cores stay warm at idle your aux pump is running fast enough.

Interesting, I thought that maybe because I didn’t change it when it stopped working and the fact that there is no fuse to blow that I had burnt something out in the IHKA. The fact that there are no heater problems would support Andrews theory. It’s just that I always thought it was either full flow or nothing.


Sent from my iPad using Xoutpost.com

A quote from BMW IHKA document: "The auxiliary water pump is powered directly from the IHKA control module through a final stage output." So indeed it could be PWM controlled, not just on/off. Unfortunately there was nothing more specific on the matter.

Thanks for that information, when I first put it in even though there was no flow I knew it was running by feel, the right side had no heat but I had read on here to rev to between 3/4K revs a few times to perhaps shift an air lock, this restored the full heating and I then started to get the roughly 25% flow. Not had in issue since (6 weeks)


Sent from my iPad using Xoutpost.com

for some reason in my mind i was thinking the aux washer pump and not the aux coolant pump .
i would perform a resistance check of the harness. from the wire in the ihka harness to the signal wire from the connector to the pump. should be less than 1.0 ohm or very near. Anything more could indicate a problem with corrosion or internal break of the wires (think only one strand carrying current) which would really drop the voltage a whole lot.

Or check the voltage with an oscilloscope - that way you can spot the PWM signal (if it IS PWM).

Don't have a 'scope? Then try your digital multi-meter on the frequency (Hz) range. If you get nada, it's likely DC line but if the meter reads a frequency of something like 1000HZ (1kHz) then its a PWM circuit. :thumbup:

I’m pretty sure it runs at varied speed.

It’s a very well engineered motor I’ve had one apart. It’s a brushless design that converts DC into pulses of power at 90° rotations. I tried to figure out what component failed to restore operation and could plot the output of the Up-down vs left-right poles and one was clearly working as designed and the other had a little blip of maybe 10% power.

I think the foxwell will show the real-time current speed but it may not be able to read the speed only request a particular speed.

Also wife’s car was different she has the 2000-1/2 design and I think hers might actually just always run which may be to blame for why hers failed and mine is still cooking.

Also, my car has always warmed up faster (including the seats which I think is in large part due to the black color of my seats and that they absorb v. reflect IR.

I’ll try to remember to get a reading from my aux pump

I looked tonight. I can only activate not select how fast and I couldn’t find the speed on my foxwell


Sent from my iPhone using Tapatalk Pro

I knew I shouldn’t have said "it’s been working fine ever since" siting at the shop today waiting on the wife the heat gradually disappeared, a quick Burst of revs restores heat. So presumably that tells me that the aux pump just isn’t running fast enough. Will try the suggestions but it will have to wait, I’m off to the south coast to see family and friends on Thursday. Have to be careful this time, last trip cost me £100 and had to do a "driver awareness course" Thanks for the help. BTW as a quick fix I had thought of putting a 12v feed to the pump. Is that likely to harm anything.


Sent from my iPad using Xoutpost.com

I don't think the auxilary water pump makes that big a difference to the heat with the engine running.

It makes 100% of the difference. At idle you get 0% cabin heat without the aux pump. When wife’s aux pump died we would have to put in neutral and force about 1800-2000 rpm though red lights or the cabin would be quite cold. This is with ambient about 30F.