Earlier this year, I replaced a busted valley hose on my 05 xj8 which was causing a large coolant leak.

For the past few months, my xj will overheat at idle or if I’m crawling through traffic, under 20 mph. It seems like the cooling fan won’t turn on.

So far, I’ve replaced the thermostat assembly with a Europarts aftermarket assembly. Even though the t-stat and temp sending unit are now new, the overheating problem has not been fixed.

Would anyone happen to know how to test the fan itself? I read another thread suggesting I unplug something near the front tow hook/fog light, but I don’t know which wire to unplug.

Or, if there are any other suggestions, please let me know!

Thank you.

 

Check fuse to fan.

Check fan relay.

Turn AC on. The fan should come on full speed regardless of engine temp - even when engine is cold.

 

I will check the fuse later on when I get home.

I didn’t think the x350 fan had a relay.

My AC will blow ice cold at speed, but if it’s been sitting for 5+ minutes the AC will blow warm-ish and the car will start to overheat.

 

I had a similar issue recently with the fan not running and it turned out to be a loose ground located behind the right headlight, fixed that up and the fan started behaving.

 

Hi 1sloXJR,

You can download the Electrical Guide for your XJR at this link:

Jaguar X350 Electrical Guide 2005

See pdf page 67 for the fan module schematic.

Constant battery power is supplied to the fan module on the Brown/Green wire via fuse 35 (80 Amps) in the Front Power Distribution Fuse Box (FPDFB).

Ignition switched power is supplied to the fan moduel on the Green/Blue wire via fuse 14 (10A) in the FPDFB.

Fan operation is controlled by the Engine Control Module (ECM) via the White/Blue wire.

You can test for proper supply voltages on these wires. You may also have one or more diagnostic trouble codes flagged related to fan operation. Have you had the car scanned?

The fan module is grounded at point G3, which is one of the two ground studs behind the right headlamp. A layer of aluminum oxide just 4 nanometers thick forms on the aluminum wire terminals, threaded stud and nut, adding considerable resistance to all electrical and electronic circuits that reference those ground points. So a common maintenance task is to disassemble the ground points behind both headlamps (two at the right and one at the left), clean away the thin whitish oxidation with a brass-bristle brush, flush with zero-residue electronic cleaner, then reassemble and tighten the nut just until it is "snug." The torque specification is a very low 6.5 ft. lbs., and many of our members have discovered the hard way how easy it is to snap a stud off of the body by overtightening the nut.

Cheers,

Don

 

I looked at the grounding points, and they were extremely corroded. After cleaning them, the fan seems to be blowing and I’m pretty sure the problem is solved.

Thank you!

 

Great news!!!