My XJR, Rose, is now back on the road after replacing the ECU with one that suppresses the immobilizer. Everything returns to normal, except an error message showing up on the temperature display panel, and a red light on the SRS Airbag on the dash. I dealt with the airbag dash light before, and wonder why it is returning, but will deal with it later. As for the air-con, the blower motor works fine, although a bit weak, as before, and there is still cool air from the air-con. Was hoping that the IDS would clear the error, but the following DTCs refused to go away:The parts diagram shows the following sensors:


#1 is MNA6550AA - "Sensor"
#3 is LNA7625AC - "Solar Sensor" (some call it the Sun Sensor, made by Denso)
#5 is LNA7605AB - "Air Temperature Sensor"

I suppose both DTCs refer to #3 being faulty as it is the only sensor inside the cabin? Wonder what this sensor does, maybe more correctly described as the in-cabin temperature sensor?

 

Firstly check the cabin sensor (No. 1)

The sensor is located on the inside of the bolster panel below the steering wheel (RHD) and has to be disconnected to remove the panel. This may have been done when replacing the ECU.

It's easy to forget to reconnect when replacing the panel. Ask me how I know.

 

D1853 is referring to part #1 in the diagram. Its a small motor and fan, located just inside the driver's door (right door in your case), mounted on the back of the dash knee panel closest to the door. It actually pulls air through to monitor internal temperature. You'll probably find it clogged full of dust and possibly not spinning (or simply disconnected!). Part #2 is the very small grille for it that can be seen on the lower dash panel.

B1250 is probably for part #3 solar sensor. Not so sure on that one.

And the error message in the temp display is probably due to a faulty or poorly connected part#5. It is mounted in the front LEFT brake duct I believe.

 

Don't clean the cabin temp sensor # 1 with solvent as this may remove some lubrication from the fan bearings . Air and a brush should be fine . Looking for your common denominator and it may be the reference voltage from the A/C ECU but since you also go a sensor fan ( a power circuit ) it points to a common connector . You'll see the # 2 small vent grill from the outside below the steering column but then your steering is on the wrong side .

I had a already colored wiring guide somewhere in my coloring book , I'll have to see if it's on my moms refrigerator .

 

Thanks very much for the various suggestions. I installed the new ECU by myself without making a visit to the mechanic, forgetting that during the earlier no-start investigation, the mechanic disconnected many wires under the panel around the steering wheel and the Driver-side's footwell, before ruling the ECU faulty. So my next step is to reconnect those wires first.

 

You'll find the A/C ECU on the side of the A/C plenum on the driver side on yours but maybe it is on the passenger side . The 4 ECU connectors will point at you at a 45 degree angle .

Check out post # 10 below :

https://www.jaguarforums.com/forum/x...window-199195/

 

Mom's refrigerator - good one ha!

 

AL NZ's XJR celebrating April Fool's Day with New Zealand Sheep!