I have a 2002 XJR X308. I just finished replacing bank 2 sensor 1 O2 sensor. After test driving a couple of days, everything seemed fine. However part of the repair was to remove the coolant reservoir and all its associated (typically brittle) hose connections). I was nervous about this so I was keeping an eye one it. It typically loses a bit of coolant over a 3 week period, requiring a top off. The oil is clean so I don't think I have a head gasket issue.

I loaned it to my daughter for a few days and told her to watch out for the coolant low message and keep an eye on the temp gauge. Of course it started overheating without the coolant sensor message coming on. The tank coolant is fine so it does not appear to be loss of coolant. So the usual suspects, thermostat, restricted coolant flow, bad fans. I am just starting to get into this.

During the overheating, I also now have the ABS light. I noticed that when it is hot and shutting the car off, only the lower left fan (from the drivers perspective) continues to run. I went out and started it this morning with the ac on and let it warm up. When the ECT got to 235 deg F, I cut it off. Only the lower left fan was again running.

What is the typical fan operation? Should both fans be coming on in normal operation if the car starts overheating? If they should then I'll test the fan.

Also is there any electrical link to the ABS or should I consider this a coincidence? I had ABS issues a couple years before that required cutting the case and resoldering the power pins. That has fixed the ABS until now.

 

Both should always run. Someone correct me if I'm wrong. I had the issue on my previous x308. With one fan running at shutoff. That is because the car is too hot. One of my cooling fans was dead. Replaced it. And no longer had the issue.
Once the car is up to temp, turn the AC to max cooling. Pop the hood, both should be running.

Fans will come on at low speed at about 205°F, and shut off at 194°F.
High speed fan specs, I can't recall off the top of my head.

 

Thanks for the quick response. That gives me a starting point as the upper right fan does not come on. I'll start looking at fuses and fan power first as I think it is too coincidental that the ABS light came on in the same event.

 

The fans run in SERIES when they run on LOW and PARALLEL when they switch to HIGH.

Both fans always spin when they are on LOW or HIGH.

 

Ok thanks again. I have JTIS running on an old XP computer as well as Carmin app on my android phone. Neither seems to provide exactly the info that matches my vehicle as near as I can tell. Somewhere else in this forum I ran across a discussion that pasted the fan circuitry diagram. I checked fuses 12 and 14 and they were good. But the diagram indicates a fan control module.

Its a little hot in Texas right now to be laying on the driveway under my car looking for this. I can follow the fan motor leads behind the fan mounting shroud over to the drivers side front where they disappear in the frame area near the headlights. I'll dig deeper one of these mornings before the blast furnace starts. Is there a dedicated FCM and if so, exactly where did they hide it?

 

A little more due diligence on my part and I've narrowed down its location as well as a more complete circuit diagram. Will proceed from there.

 

The individual fans can fail. I saved the old fan assys when I worked at the dealer so I could salvage the good motors from the 'cooling-module'.

Jaguar only sold the fans as an assembly so I replaced the faulty fan with a good fan from another assy to get BOTH fans working again.

Pretty quick and easy to get the fan assy out on the bench for testing the individual fans if the wires seem to be intact.

 

Quick follow up. The upper fan is bad. The thermostat is stuck closed (verified by heating in a pan of water). And the water pump has a slight leak as the gasket basically disintegrated. So a new water pump, thermostat and fan should take care of the overheating problems.

The source of the ABS light is still undetermined. I'll check the wheel sensors first. I have not had a single ABS issue since I repaired the connector pins about 3 years ago.

I think the ABS is coincidental to the overheating and all these issues are coincidental to loaning the car to my daughter. Murphy is alive and well!

 

My guess on the ABS is a faulty front 'link-harness' to the sensor(s).

 

Replaced the thermostat, one fan motor and the water pump. New antifreeze and topped off the power steeting fluid.

All is right with the world again. Even the ABS light went out. There must be some causality between the two issues but I'll be darn if I can link them.

Anyway, the cat is purring again.

 

I have the ABS light sometimes coming on with the usual messages "Traction control fail", "Stability control fail" (but no restricted mode) and the scanner tells it is the "ABS pump motor circuit failure" which, I believe, means problem in the solders. I haven't done them yet since the trouble messages do not cause "Restricted performance" and disappear on engine restart (looks like interruption of the power to the motor is only momentary, i.e. the solders have not completely deteriorated).

Anyhow, the ABS light and the messages only come on if I leave the engine idling for some 20 min. from the cold start and never come on if I drive the car normally. My fans and the cooling system are all very good. It looks like the trouble with the solders is exacerbated by the under hood temperature which goes somewhat up if the car is not moving.

 

takes like 30 minutes to fix the module

no asc can catch you off guard in the rain