My 04 S-type V8 (NA) started having DCCV issues and burnt the CCM board. I replaced the DCCV. I followed the repair link on the jag forums to fix the burnt trace on the CCM with a bypass wire carefully soldered on the board. Now measures a comfortable draw of 0.8 amps instead of the 9 amps it drew with the old one.
Back in business with CCM controlling the DCCV for about a day. Then Fuse 32 blew (10A). WTF. Dragged out the meter, measured across the burnt fuse terminals to see only 1 amp draw. Turned on the AC, still only 5 amps draw. Replaced 10A with 15A fuse and worked for about 3 days then blew the fuse. Checked amp draw again. All good. Replaced 15A with 20A fuse and ran again with no AC for about 5 days.
Was almost sure the AC Clutch was the issue since the fuse was still holding when this morning it blew again. No AC was used to this point so that ruled out the AC clutch. Amp draw still shows about 1 amp without AC and 5 amps with.
Only thing left is the Aux Circulating water pump but I've never heard that to be an issue on this forum. Any other ideas?

 

Great trouble shooting!!

Unplug the AUX pump and see if the fuse still blows then reconnect if no change. The AUX pump tends to die and not short out but it’s worth a check.

Unplug the A/C clutch and see if the fuse still blows. You may want to change the clutch anyway if you have a lot of miles. On other cars I have worked on you sometimes have to add a shim to the clutch as it wears to keep it engaging. But I have not seen this problem with the S Type.

You could have a chafed wire that is fine until it is moved and touches something. I have noticed the black wire on the A/C clutch often has the insulation degraded from all the oil that gets on it. I can see copper on mine but it does not seem to be a problem.

Get under the car and inspect the black wire that runs to the electrical plug on the A/C clutch. Since the wire was black I figured it was a ground wire and it did not matter if it was insulated or not? Just a guess here.

Can you list what is run off that one fuse?
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I will start with the AUX pump disconnected. I was surprised today after driving to work that there appears to be little effect on the climate control with the AUX pump disconnected. I read somewhere on this forum that it's only real purpose was to keep the heater working well at an idle. Heat was flowing just fine at idle without the pump. So far fuse is holding.
As far as I know the only things running off that Fuse 32 are the DCCV, the AUX Pump and the AC Clutch. Everything else seemed to work fine with the fuse blown.
I did note that the mini fuse configuration, once blown, lends itself well to an inline ampmeter since the top of the fuse, in place, has miniature terminals you can make contact with the meter leads placing the meter in series with the cct. The only caveat here is that whatever blew the 10, the 15 and then the 20 amp fuse may well blow the fuse in your meter if your's is like mine and only capable of 10 amps DC.

 

You are correct about the AUX pump but I will say that I changed mine for a different symptom so I am not real sure it ONLY affects heat at idle.

Let us know if the fuse lasts or not.
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Thought I would chime in again on this fuse 32 problem. I've obviously got a bad Aux pump cuz now after 3 weeks of running with it disconnected I am still on the same 10amp fuse. Oddly enough, weather being what it is here in Surrey BC, I need heat in the morning and AC in the afternoon. The lack of aux pump has not shown itself to this point. Heat still flows a few minutes after the engine temp gauge shows some heat. I do note that at idle the heat is a tad less than at driving so the comment about needing it for idle is true but heat still flows at idle, just not the same as at 1500 rpm. I think I'll pull the aux pump and plumb it straight through for the summer. The contraption is almost 300 on ebay and I don't want to chance a used one for 150. I'll see if I can fix it myself. Just glad to get back to normal DCCV and AC operation.

 

Maybe I have got my info all wrong here...

I thought that that aux pump was designed to keep the hot water circulating when the outside temp was cold and the engine was switched off, so as to keep the car warm a little longer. At all other times, including idle, the water pump did the work.

No?

 

No. The AUX pump is mainly for heat at idle. The S-Type has the engine so low in the chassis that the heater core is higher than the engine so the mechanical pump does not push coolant uphill very well at low engine speeds. It appears that you do get some heat without it at low engine speeds.

Jaguar released a TSB about replacing the AUX pump and the main symptom is low or no heat at idle.

I don't know how good of a mechanic you are but the AUX pump is rebuildable and usually needs the brushes replaced. There is not an exact replacement but at Radio Shack you can find brushes that can be modified to work. Several people have rebuilt them successfully.

I did not know this and just replaced the pump. You can get it for a much better price if you use our forum sponsor Jaguar dealer. My old pump still works on the bench so I am still puzzled if the AUX pump was really bad or not. I kept it in case I wanted to try the rebuild idea later on.
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Good to know, tbird6. Like you, I had my aux pump changed before I read that it was probably just brushes that needed replacement. So, I too have the old pump in the garage, awaiting my attention. Probably going to wait for a while, since no hurry.

 

Good to know Tbird. I will definitely give that a whirl. Poor brushes can raise the motor current to 5 or 6 times the rated draw so in a way that makes sense. My biggest concern is whether or not the seal between the impeller in the coolant pump and the actual motor is leaking. That may not be something I can get parts for. I know the seals that separate the DCCV valve in the coolant line from the actual solenoid are what packed it in on my car so when I opened up the old DCCV on the bench, I could see why the DCCV was shorting out.

 

Just a follow up to where I am now. With the help up this forum I managed to fix a burnt trace in my climate control module at no cost to me and replaced the DCCV at a greatly reduced cost from Amazon.ca.

When I put it all back together I kept blowing fuse 32. I tracked the problem to the Auxiliary cooling pump. I removed the pump and used a 90 degree plastic elbow to bypass the pump and still run the car. However when I took out the pump I noted that there was evidence of leaking coolant on my brand new DCCV. Not cool.

I cleaned everything and after a few days with the plastic bypass in place there was no more dripping. So I believe the problem started with the Aux pump dripping onto the DCCV eventually causing both to fail.

I tried to fix the Aux pump but the brushes had been arcing for so long that the plastic housing holding them in place melted and seized the brushes in the housing. There was no removing them without destroying the housing so I will need a new pump.

So now I see the high cost of Aux Pumps on the net (250 and up) but I am drawn to the 4.0L pump on the earlier S-type which costs half as much. The orientation and plug appear identical, just the rubber mount seems different. That should be transferrable from my old pump. It just slides off the motor barrel.

Anyone out there tried a different pump like this instead of the 250 dollar one on ebay?

 

Thank you for the update!

 

Well you might consider finding a used one from a late model S Type? AUX pumps don't go out real often but you are still taking a chance with a used one.

I have not checked if the Lincoln LS AUX pump is the same but they are cheap and common in the junk yards so it might be worth trying to pick up one from a 2005 or 2006 LS.

Does anyone know if this part swaps between the two cars? I really think it does because they look the same. I have a 2003 LS and a 2005 STR. I have changed my STR pump but the LS has been fine after the DCCV change so that AUX pump is still working OK.
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