Not joined yet? Register for free and enjoy features such as alerts, private messaging and viewing latest posts and topics.

Electrical assistance needed - N46 cooling pump

Discuss problems you have had or are having with your Z4
User avatar
enuff_zed
Lifer
Lifer
Posts: 9812
Joined: Wed Oct 26, 2016 11:05 am
Location: Attleborough, Norfolk

Electrical assistance needed - N46 cooling pump

Post by enuff_zed » Thu Nov 10, 2022 4:31 pm

I've very quickly got to the limit of my understanding and need some electrical assistance please.
N46 2.0i engine has an auxiliary water pump mounted under the air box. A hose runs into it then out to the heater, from there back to the expansion tank.
I have no hot air in the cabin at all.
I found the hoses to and from the heater to be cold. The hose running to the auxiliary pump is getting hot, but not its outlet.
I have discovered there is definitely 12v going to the pump plug with ignition on '2'.
I have also wired the pump across a battery and it runs fine.
I have done the same with a second pump. That works fine across the battery too.
Both pumps have been fitted into the car. I know they both run on 12v and I know 12v is coming out of the plug.
BUT............... neither pump will run.

What am I missing? Don't think it needs water pressure as they run across a battery ok?

I am no electrician, so although something i the back of my mind is telling me I need amps as well as volts, I have no idea how to go about checking this! Or am I barking up the wrong tree?

Help?
E89 20i SDrive M Sport - mine
E85 2.5i auto - Vall's
E85 2.0i facelift - Rescued as a winter daily
E85 3.0i manual - Project Cheapskate
E85 3.0i auto - gone
E85 2.5si - gone
E85 2.2i - gone

Online
User avatar
colb
Senior Member
Senior Member
Posts: 1238
Joined: Wed Nov 13, 2019 9:45 pm
Location: Newport, South Wales UK

Electrical assistance needed - N46 cooling pump

Post by colb » Thu Nov 10, 2022 4:58 pm

Got to be an impeller inside the pump to force the water through it, the fact that you can hear the motor working makes me wonder if the impeller is not being turned by the motor spindle hence no flow or maybe the heater matrix is blocked preventing flow.
Z Shed Cymru member
1999 1.8 Z3
2003 2.5 Z4
1998 Honda Deauville 650

User avatar
enuff_zed
Lifer
Lifer
Posts: 9812
Joined: Wed Oct 26, 2016 11:05 am
Location: Attleborough, Norfolk

Electrical assistance needed - N46 cooling pump

Post by enuff_zed » Thu Nov 10, 2022 5:51 pm

colb wrote: Thu Nov 10, 2022 4:58 pm Got to be an impeller inside the pump to force the water through it, the fact that you can hear the motor working makes me wonder if the impeller is not being turned by the motor spindle hence no flow or maybe the heater matrix is blocked preventing flow.
Nope, both motors spin fine when across a battery, and I can see the impeller turning in both of them.
But connect them to the car loom, which definitely has 12v at it and nothing happens. Weird.

Had a similar issue with a washer pump on an old Capri years ago. Showed 12v but wouldn't work. Discovered the spade connector at the fuse box was corroded which must have caused a high resistance. Cleaned it and it worked fine.
So I'm wondering if it's a similar issue here. Not sure here I start though? Tempted to run an ignition live to it, with a new plug, from somewhere else.

Tomorrow's job is to use a spare battery to power the pump on the car and see if it will run in situ and cure my lack of heat at least.
E89 20i SDrive M Sport - mine
E85 2.5i auto - Vall's
E85 2.0i facelift - Rescued as a winter daily
E85 3.0i manual - Project Cheapskate
E85 3.0i auto - gone
E85 2.5si - gone
E85 2.2i - gone

deltasierra
Newbie
Newbie
Posts: 21
Joined: Thu Jun 23, 2022 7:32 pm

Electrical assistance needed - N46 cooling pump

Post by deltasierra » Sat Nov 12, 2022 10:39 pm


User avatar
smorris_12
Member
Member
Posts: 156
Joined: Mon Apr 18, 2022 2:14 pm
Location: Somerset

Electrical assistance needed - N46 cooling pump

Post by smorris_12 » Sun Nov 13, 2022 12:24 am

Generally it's easier to switch the ground side of a circuit so devices get a permanent 12v and have the 0v/ground side switched. So seeing 12v isn't surprising.
------
Scott

Where are we going and why am I in this handbasket?

2006 Z4 2.5si Silbergrau und rot

User avatar
enuff_zed
Lifer
Lifer
Posts: 9812
Joined: Wed Oct 26, 2016 11:05 am
Location: Attleborough, Norfolk

Electrical assistance needed - N46 cooling pump

Post by enuff_zed » Sun Nov 13, 2022 8:59 am

smorris_12 wrote: Sun Nov 13, 2022 12:24 am Generally it's easier to switch the ground side of a circuit so devices get a permanent 12v and have the 0v/ground side switched. So seeing 12v isn't surprising.
Hmmm, but I thought that putting my voltmeter across the two pins of the plug and getting 12v must mean the circuit is complete? I’m got checking from one pin to earth?
E89 20i SDrive M Sport - mine
E85 2.5i auto - Vall's
E85 2.0i facelift - Rescued as a winter daily
E85 3.0i manual - Project Cheapskate
E85 3.0i auto - gone
E85 2.5si - gone
E85 2.2i - gone

User avatar
enuff_zed
Lifer
Lifer
Posts: 9812
Joined: Wed Oct 26, 2016 11:05 am
Location: Attleborough, Norfolk

Electrical assistance needed - N46 cooling pump

Post by enuff_zed » Sun Nov 13, 2022 9:02 am

deltasierra wrote: Sat Nov 12, 2022 10:39 pm https://bimmerprofs.com/electric-waterpump/

Maybe this explains more,
Thanks but this seems to be for the main pump? My issue is the auxiliary pump that circulates coolant to the heater. I have no codes and have fitted another pump too.
E89 20i SDrive M Sport - mine
E85 2.5i auto - Vall's
E85 2.0i facelift - Rescued as a winter daily
E85 3.0i manual - Project Cheapskate
E85 3.0i auto - gone
E85 2.5si - gone
E85 2.2i - gone

User avatar
smorris_12
Member
Member
Posts: 156
Joined: Mon Apr 18, 2022 2:14 pm
Location: Somerset

Electrical assistance needed - N46 cooling pump

Post by smorris_12 » Sun Nov 13, 2022 10:41 am

enuff_zed wrote: Sun Nov 13, 2022 8:59 am Hmmm, but I thought that putting my voltmeter across the two pins of the plug and getting 12v must mean the circuit is complete? I’m not checking from one pin to earth?
Because test meters are very high impedance the smallest amount of current to ground thru the controller will give you a reading. All it takes is a large resistor being used in the "Pump Open Circuit" test circuitry passing a few microamps and you'll get your voltage reading.

Similarly, a high resistance joint as per your Capri would do the same thing. Enough current to give a reading but nowhere near enough to drive a motor.

You could try substituting a 5W bulb for the motor which would eliminate any mechanical problems and let you see if the circuit is being switched correctly.
------
Scott

Where are we going and why am I in this handbasket?

2006 Z4 2.5si Silbergrau und rot

User avatar
enuff_zed
Lifer
Lifer
Posts: 9812
Joined: Wed Oct 26, 2016 11:05 am
Location: Attleborough, Norfolk

Electrical assistance needed - N46 cooling pump

Post by enuff_zed » Sun Nov 13, 2022 10:47 am

smorris_12 wrote: Sun Nov 13, 2022 10:41 am
enuff_zed wrote: Sun Nov 13, 2022 8:59 am Hmmm, but I thought that putting my voltmeter across the two pins of the plug and getting 12v must mean the circuit is complete? I’m not checking from one pin to earth?
Because test meters are very high impedance the smallest amount of current to ground thru the controller will give you a reading. All it takes is a large resistor being used in the "Pump Open Circuit" test circuitry passing a few microamps and you'll get your voltage reading.

Similarly, a high resistance joint as per your Capri would do the same thing. Enough current to give a reading but nowhere near enough to drive a motor.

You could try substituting a 5W bulb for the motor which would eliminate any mechanical problems and let you see if the circuit is being switched correctly.
Thank you.
I'm away for a week now, but will try that on my return.
Newtis circuit diagram seems to suggest power comes from Fuse 10, through the motor then on to the AC controls.
Fuse looked ok, but I swapped it for a new one to be sure.
So I'm wondering if maybe there could be a fault within the switch assembly on the dash.

Anyone know if pre- and post-facelift heating controls are interchangeable? I know the knobs look different, but i have an early one spare that I could slave into this facelift car as another check.
E89 20i SDrive M Sport - mine
E85 2.5i auto - Vall's
E85 2.0i facelift - Rescued as a winter daily
E85 3.0i manual - Project Cheapskate
E85 3.0i auto - gone
E85 2.5si - gone
E85 2.2i - gone

User avatar
enuff_zed
Lifer
Lifer
Posts: 9812
Joined: Wed Oct 26, 2016 11:05 am
Location: Attleborough, Norfolk

Electrical assistance needed - N46 cooling pump

Post by enuff_zed » Sat Nov 19, 2022 2:53 pm

Well a random comment by bigwinn sent me off at a tangent and I found this old thread
viewtopic.php?p=1381879&hilit=hedgehog#p1381879
No idea exactly how the 'hedgehog' cured the heater from only blowing cold, but I have a spare and am going to slot that in whenever the missus stops giving me jobs to do!
I am hoping it somehow signals the auxiliary pump, but it's not hard to get at so worth a punt.
E89 20i SDrive M Sport - mine
E85 2.5i auto - Vall's
E85 2.0i facelift - Rescued as a winter daily
E85 3.0i manual - Project Cheapskate
E85 3.0i auto - gone
E85 2.5si - gone
E85 2.2i - gone

User avatar
smorris_12
Member
Member
Posts: 156
Joined: Mon Apr 18, 2022 2:14 pm
Location: Somerset

Electrical assistance needed - N46 cooling pump

Post by smorris_12 » Sat Nov 19, 2022 8:31 pm

Reading that thread it sounds a bit specious (or misremembered) to me. The FSR is merely a PWM motor controller and (certainly on an E36) has no feedback to the heating controller. Feedback is provided by the cabin temperature sensor. Asking a motor controller its opinion of cabin temperature is akin to asking the fighty drunk in the pub for his opinion of Kwase Kwatang's special fiscal operation.

I can't bring up the WDS on this laptop (grrr, Java trying to protect me from something) or I'd check out exactly how the system works. Traditionally there was always a solenoid controlled water valve to modulate the cabin heat. I don't know if this has been superceeded by having a pump alone or if it's in addition. But that's where I'd start.
------
Scott

Where are we going and why am I in this handbasket?

2006 Z4 2.5si Silbergrau und rot

User avatar
enuff_zed
Lifer
Lifer
Posts: 9812
Joined: Wed Oct 26, 2016 11:05 am
Location: Attleborough, Norfolk

Electrical assistance needed - N46 cooling pump

Post by enuff_zed » Mon Nov 21, 2022 4:21 pm

Right then!
Today I delved into the dash and firstly discovered someone has been there before as there was no Air Mixer Flap Actuator fitted!
What a pig that is to access! Luckily I had a spare and managed to get it in to place.
The Hedgehog had to come out for access so I swapped another one in.
Then while I was at it I managed to somehow reach the heater temperature sensor and swap that.
Finally, slaved in another control panel.
No change! Auxiliary pump will not run!

Anyone got any ideas?

Thinking my next step is to rig a separate supply to the pump and see if it runs, sends hot water to the heater and gives me heat in the cabin.
If that works then I think I'll simply make up a length of loom and run it to the pump from a suitable ignition live.
E89 20i SDrive M Sport - mine
E85 2.5i auto - Vall's
E85 2.0i facelift - Rescued as a winter daily
E85 3.0i manual - Project Cheapskate
E85 3.0i auto - gone
E85 2.5si - gone
E85 2.2i - gone

User avatar
N4LLY
Senior Member
Senior Member
Posts: 1230
Joined: Sat Nov 24, 2018 12:11 pm
Location: Kent

Electrical assistance needed - N46 cooling pump

Post by N4LLY » Mon Nov 21, 2022 4:54 pm

Take it to a BMW main dealership :D
Image

2014 20 M sport Valencia Orange

User avatar
enuff_zed
Lifer
Lifer
Posts: 9812
Joined: Wed Oct 26, 2016 11:05 am
Location: Attleborough, Norfolk

Electrical assistance needed - N46 cooling pump

Post by enuff_zed » Mon Nov 21, 2022 4:56 pm

N4LLY wrote: Mon Nov 21, 2022 4:54 pm Take it to a BMW main dealership :D
Yo-ho-ho!
Never!!!

Its a cheapo 4-pot. If I can jury rig it I will.
E89 20i SDrive M Sport - mine
E85 2.5i auto - Vall's
E85 2.0i facelift - Rescued as a winter daily
E85 3.0i manual - Project Cheapskate
E85 3.0i auto - gone
E85 2.5si - gone
E85 2.2i - gone

User avatar
N4LLY
Senior Member
Senior Member
Posts: 1230
Joined: Sat Nov 24, 2018 12:11 pm
Location: Kent

Electrical assistance needed - N46 cooling pump

Post by N4LLY » Mon Nov 21, 2022 4:57 pm

enuff_zed wrote: Mon Nov 21, 2022 4:56 pm
N4LLY wrote: Mon Nov 21, 2022 4:54 pm Take it to a BMW main dealership :D
Yo-ho-ho!
Never!!!
Snigger :P :D
Image

2014 20 M sport Valencia Orange

Post Reply