My 2001 Jag XJR low beams don't want to work. At first whenever you turn on the turning signal, my low beams would go out. Once the turning signal is turned off, my low beams turn back on. Now, my low beam headlight wont come on at all. My high beams work fine but i have to manually hold the passing high beam lever to keep them on. This almost sounds like a ground issue. I checked the relays and they are working fine. Any suggestions?

 

From the circuit diagrams, the LH & RH front exterior lighting have their own LH & RH side grounds, so it's unlikely that both grounds have failed simultaneously-although it's good practice to check them anyway.

The fact that the main beams can be energised manually means the fuse, relay & high-current paths are working, so I'm thinking the fault lies with the relays not being energised to switch on the lights.

The Main Beams, Dipped Beams & Fog lights are all relay-controlled. The signal to energise the relays comes from the Body Processor Module-the BPM. The BPM gets its 'instructions' from the column lighting stalk switch.

So the column lighting stalk switch signals the BPM to energise the relay for whichever lighting function you have selected, and once energised the relay supplies the main high current to the headlamps.

You could start by checking that the electrical connector for the column lighting switch is securely plugged in & also that the multiplug for the BPM is also securely plugged in.

If these are both ok then it's possible that either the BPM has failed or the column lighting switch has also failed.

You need to look at the circuit diagram for the front exterior lighting (JTIS, Fig 09.1) & check that the BPM applies the appropriate ground to the earth side of the relay coil for that particular lighting function when you select it. The other side of the relay coil comes directly from the main +ve battery bus line & should be live at all times for the Main & Dipped beam functions.

The BPM works by applying a ground to the relay coil to energise it, when instructed by the selected column lighting switch function.

 

Thanks Red. I just started rotating the stalk and the lights twitched on and off once or twice. I'm sure it's something iniside manfuntioning. I'll check it tomorrow.

 

From what I've read on other posts here, it's probably the solder joints on the column stalk switch...