When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
On my '02 V6, my radiator cooling fan does not seem to be running when it should. I've only had time to run some very preliminary troubleshooting and plan to tackle it in-depth tomorrow. So far all I've done is check the two fuses (#5 and #25) for available power and continuity. There's just too much rain today to get any more involved. Springtime is when even Oregonians say, "You know, I'm getting kinda tired of this rain..."
I've been reading up on the V6 Cylinder Head Temperature (CHT) sensor. Per my Jaguar training manual, the CHT directly measures the metal temperature, not the coolant, to allow operation of the failsafe cooling strategy even if coolant has been lost. My car a big coolant loss last week (upper radiator hose fitting failed), since repaired. But the way I'm reading this, even if I didn't bleed the system correctly and there's a big air pocket, the CHT doesn't care and only reports the actual temperature of the metal.
Driving home today, I got stuck in slow traffic and the temp gauge started climbing. I rolled down the window and never heard the fan kick on. I even pulled over to be sure and opened the hood, and with the temp gauge indicating about 3/4 of the way up, the fan was definitely not running. My scanner agreed with the temp gauge, too. As soon as I could get some forward motion and airflow through the radiator, the temperature cooled right back to where it should be. Slow down, it climbs. Of course, I can't duplicate the climbing temperature in my driveway.
Three paragraphs later, my big question: Is the CHT the only sensor feeding temperature information to the PCM and/or the dash gauge? As near as I can figure, that is how it works, but I'm not positive. This is probably one of those things so basic, it wasn't really covered in the manual. As a former tech writer, I want to slap this author around but that's beside the point right now.
On other vehicles I've owned, the dash gauge was controlled by one sensor and another sensor fed the PCM, making two independent circuits. Confirming this detail is very important for my troubleshooting plan tomorrow. Surprisingly, my manuals only have the vaguest details for troubleshooting a fan that doesn't run. After more basic checks, one thing I'd like to try is using some resistors to trick the CHT circuit to indicate a higher than normal temperature so the fan should kick on. (I have a table with the sensor's temperature-to-resistance values)
ECT SENSOR: ENGINE COOLANT TEMPERATURE SENSOR PI39
section 3.1
Thanks, but it's a V6. (see original post) I'm looking at CHT sensor PI13, section 3.3.
I was reading more about the CHT and the overheat protection logic. Interesting stuff.
Doing some armchair troubleshooting, I'm pretty sure I'll be looking at a fan motor or controller. It's a bit annoying that the motor is not available separately. Welcome to the joy of European car ownership. (I went through the same thing with an Audi.) You have to buy the entire motor/blade/shroud assembly for around $700. The control module new is over $300. To minimize downtime, I pulled out the parts shotgun, fired from the hip, and ordered a guaranteed used fan assembly on eBay for $135 (this also includes the control module) and it will hopefully be here before the weekend.
I did some more armchair troubleshooting. Two signals control the fan, via pulse-width modulated grounds. One is from the PCM. The other comes from the air conditioning module. I don't know all the specifics, but it would appear either command will turn on the fan and control the speed. Just guessing, but the higher speed command probably takes precedent.
Since the AC was on (should have commanded the fan to run regardless of coolant temp) and the car was also running hot (also should have commanded the fan to run), it's highly unlikely both signals were bad. That would point to either the cooling fan module or the fan itself. I hope to know more this afternoon when I finally have some non-monsoon time under the hood.
That's my TheoryDuJour(tm) and I'm sticking with it, at least until the wind changes direction.
Well I don't know if this is of any help but had a problem with loss of coolant on my V8 blew the header tank overflow hose joint and water pump housing was at fault so got that all good again but it never gave me issues with the heating gauge moving up actually its never moved above half way ever since I've had it. But here's the thing I have untold issues with the wiring. You'll see a post of mine on that subject if you delve and some pics which are very colourful.
The wiring is shocking and on many occasions I've had the whole wiring out of the fuse box only to find that underneath is all corroded from the heat exchange and damp condensation from engine bay. If not checked already I'd meter the wiring back form fans to fuse box and to sensor and ensure all is good as its sometimes something as simple like that......that's hoping!!!!
As best I can determine, a mechanic once ran off with a Jaguar engineer's wife. The forlorn engineer plotted his revenge against mechanics everywhere and succeeded beyond his wildest dreams. He was in charge of designing the S-Type radiator fan shroud.
The shroud was a booger to remove. I followed every step in the manual, and even then it only cleared by a fraction of an inch. The worst part is the bottom wraps forward about an inch under the radiator, with two U-shaped clips to secure it. If it weren't for this lip and two miserable clips, it probably would have been a twenty minute job to pull the shroud.
Anyways, I think I found the problem with the fan motor... The first thing I did was check continuity through it and got nothing. I tried spinning the blades, wondering if I had a dead spot, but then the fan physically bound up.
The first picture shows what I found. Of the four brushes, two were completely gone. The spring for one brush had got wrapped around the commutator and wore all the way down through the individual segments into the core. The binding I felt was the spring grabbing the commutator.
This poor motor is beyond repair. Glad I have a spare on the way. The next picture shows the data plate, Jaguar part # 9010695. I tried searching for that but only got some hits on eBay Germany.
For anybody else looking at a dead motor, if it wasn't damaged like this, you could dress the commutator on a lathe and replace the brushes. I've been able to bring other similar motors back to life, but not this one. No idea exactly where to get the brushes, but they are likely a fairly standard size. One word of caution: When removing the fan disc, the threads on the nut are left-handed.
Nasty old state, good you got to it after testing it out, these issues are frustrating which I've learnt to take the easy route first, metering everything out as a by law...well done!
I looked a little closer at the brushes, or where they should have been... What I thought were the two remaining brushes was actually graphite dust built up like a plug around the end of the spring. Those springs (plus one more that was bare) were riding directly on the commutator. The fourth spring was wrapped around the commutator. It is amazing to think this motor could continue running in that condition to create the damage that it had.
Bump to an old thread. If you find yourself here due to a problem with the cooling fan on an early model, please see this thread for a how-to on access and repair:
03-15-2016, 08:34 PM
Interface from CHT Sensor to Temperature Gauge?
