X300 auxiliary heater pump

On my new acquisition I have no heating. Coolant does get warm (needle just below center) and I can feel one hot hose on the heater valve. So I guess the valve opens. Should I feel vibrations on the auxiliary water pump? I have driven the car for a while, set the temperature to hot but could not feel the pump running.
I probably have to remove the pump to inspect the brushes anyway, so I wonder if it is worth buying a second hand one to replace the brushes on and then swap the pump. All the pictures I have seen of disassembled pumps showed a badly worn collector, and I guess that is due to the brushes having worn out to the spring. Hopefully a working used one looks much better and will run for a long time after replacing the brushes.


Thinking about it, maybe I should just buy this:

Cheaper than a used original one, and probably will work just as well. I wonder if the hoses will fit…

What mystery car do you have???

I have a 3.2l X300. I don’t quite get what you are suggesting with your question.

It is this pump I am talking about;

You are asking if parts will fit your car but we don’t know what car you have.
Cars in this forum section are from 1995MY to 2009MY.

Oh, OK, I thought X300 was a good enough description. I don’t believe the heating system is different between the 3.2, 4.0, 6.0 and XJR. But that was just an assumption, so please let me know if that assumption is wrong.
I guess the confusion started when I called the pump “auxiliary heater pump”. This is probably the wrong name for it. I am talking about a pump that is auxiliary to the main pump and feeds the heater matrix. It probably came across as “a pump for an auxiliary heater”. The fact that the pump I was showing is for an auxiliary heater probably added to the confusion. I was merely thinking about repurposeing it to replace the most likely dead one that feeds the heater matrix in my 3.2l x300.


The electric pump is used in the XJ6 (X300) as well as the XJ8 (X308 & X350) but they are all different part numbers and some have different electrical connectors.

The X300 designation on this form is confusing because it covers sedan from 1995MY to about 2009MY encompassing a few different models.

The X300 and X308 are somewhat similar but the X350 is VERY different and is more closely related the the X202 (S-Type) with an aluminum body.

Leaving out the Make,Model,Year has us guessing.(kinda like asking "will these clothes fit me?)My question is FIT WHOM?

Ok: Jaguar, XJ6, X300, 3.2l, manual, mid 1996, VIN 777???.
Will the Pump vibrate on that specific model when it is running? Will it run when the engine is hot and temperature is set to “HI”? It does not and that has me thinking it is the cause for my heater remaining cold.

Assuming that is the case, I am wondering if there is any harm in replacing it with a similar pump (shown in the link) that is for a different make, model, year and application, but a lot cheaper new than even a used original one. I would have thought if the hoses fit on that pump, it probably has a similar flow rate and will do the job just fine.


If you unplugthe solenoid valve it defaults to open if no heat then the brushes on the pump will be kaput.


Just ‘jump’ the relay for the heater pump and listen or feel the pump. You don’t need the engine on just make sure the 30/87 connections are joined.

I sometimes used the pump to bleed the cooling system when I worked at the Jaguar dealer. Running the pump should move the air to the reservoir.

Info .pdf for you. You should download the Electrical Guide S96_SED for the entire guide.
96X300Climate1.pdf(672.9 KB)
96X300Climate2.pdf (1.0 MB)

Thanks Neil and Bob!
I am positive the pump is dead now and will try the cheap one I found as a replacement. I hope it is the only reason the heater does not work, i.e. hopefully the heater matrix isn’t blocked and the cotrol valve is still working.


Harald, it is less than a 1 hr job to remove the pump (no need to drain you’ll lose an eggcup of coolant ) dismantle and if you need to fettle bigger longer brushes to size if you can’t find the correct ones. Reassemble and refit.
Be careful bending the brass housing when inserting the replacement brushes.

Appart from that air box being in the way it looks straight forward to remove the pump. Replacing the brushes is not a problem, it is just that I doubt the pump will last very long afterwards. All the pictures of disassembled pumps I have seen showed a badly worn collector. I’ll look at it anyway, but have also bought that pump for €30 I showed in the link. If the hoses fit, I’ll probaly install that instead of fixing the original one.

Do let us know if it fits!

I will do. It hasn’t arrived yet though.
Also, I seem to have a second problem. Engine temperature drops when I am driving faster. A new thermostat is on the way…

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Ok, the pump has arrived. It looks like it will fit, but I would have to fabricate a mounting bracket for it (not a big deal). I also had a look at the old pump, and what shall I say - silly me assumed dead brushes, but actually it is only a broken wire. The brushes are still good, possibly because this is a car from southern Italy and might not have needed a lot of heating…

I fixed the wire and the pump now runs when I supply it with 12V. However, it does not appear to run when it should in the car. I will have to check the rest of the wiring now. Fuses, relay and possibly the temperature sensor according to this thread:


Bridging the relay results in the pump running. 12V are present on the relay coil, but the climate control doesn’t pull down to ground to switch the relay on. I have no error codes in the climate control module.
What do I try next?
What is the ECT the other thread I linked to is taking about? Where do I find it and how do I check it?

There are two sensors on the thermostat housing. I am still not sure which one is the ECT (assuming that it must be one of them). Is the other one for the temperature gauge?
What resustance should I have whith hot and cold engine?


I can drive my car from March til October. Last year it became warm and I managed to ignore the problem. But now it is sunny but cold, I am keen to drive the Jag and still have no heating.
I am at a loss what is going on here. So far I have checked the following:

  • Pin 67 on the climate control module (on the right side of the center console, behind glove box panel) does not get pulled down. If I pull it down by hand, the relay in the engine bay switches, the pump runs and I do get heat.
  • The heated rear window also does not work (it might or might not be coincidence). But it lead me to belive the engine speed signal might not be present. I found out I am not the first one who had that idea (the insulation is stripped on that wire). I checked with an oscilloscope and found correct (3 pulses per engine revolution) on pin 6 of the control module
  • I have replaced the climate control module with a used one that was advertised as working (you never know, but unless this is a common fault I find it hard to belive it has the exact same fault as mine). No change in behaivour.

Any ideas what to check next? I am not sure what pin 22 ‘Water Pump Ground’ does? Also, I don’t know what signals to expect on the various sensor inputs. Can the coolant temperature signal on pin 40 cause problems? It is a pulse width modulated signal - what pulse width is a good signal?
All the other sensore should be ignored whent the temperature control is set to “HI”, shouldn’t they?

Help! I am about to bridge pin 67 to ground…
That doesn’t solve the heated rear window problem though. Maybe I should start looking at that problem next to find out if this is related or not. It appears to be related though, not even the light in the switch comes on, and that is the same with a second control panel I have tried…


How is temperature controlled by the system? Is it just the heater valve opening and closing? I have pulled the heaterb pump control line to ground for testing, and now it gets very warm and temperature is not control. I assume the heater valve is not operated either and it is normally open.

The conclusion is that leaving the pump always on is not a solution. So I need to continue searching for the problem.