Hello
I am looking for a solution to the following problem:

My left rear park light does not come on. (not the bulb)

The wire from the light has been traced to a control unit near the engine bay.
There is no current on the wire coming from the control unit. (strange but it looks like there is no fuse or relay on the wire from the light to the control unit)

The mechanic that checked this out said that a possible cause could be damage to the control unit due to incorrect connections when a tow hitch was put on the car. (both park lights on the connector were connected to this now faulty wire)

Any thoughts on how to fix this?

Cheers Ragnar

try the CJB reset, I had similar on mine, it's as simple as turn on ignition without starting procedure depends on manual or auto, turn it off again, CJB is reset hopefully problem solved.

Hi
Thanks for the reply

Tried the CJB reset but it did not work

cheers Ragnar

Modern cars have dispensed with many of the fuses. The circuit board monitors the current to individual lamps, if the current is too much (ie shorted) or too little (corroded joint) then the circuit board cuts the power.

Many of the boards actually keep sending a test pulse every second or so just to check that the fault still exists - try checking on voltage rather than current. A dedicated fault code reader will tell you which circuit is down and why. This means that the manufacturer could actually display on the dash when any of the lamps were out  Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner

Hi Andy

Are you saying that maybe correcting the tow hitch connection might lead the ecu to start sending current to the wire in question?

Possible Fault Codes

B10F5-11 Left rear position light - circuit short to ground
Left rear position light circuit - short to ground
Refer to electrical circuit diagrams and check left rear position light circuit for short to ground

B10F5-12 Left Rear Position light – short circuit to power
Left rear position light circuit - short to power
Refer to electrical circuit diagrams and check left rear position light circuit for short to power FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

If the ECU determines there is a fault it will cut the power to the lamp in question.
Restoring the power depends on the guy who wrote the control philosophy,
(1) many cars require the ignition to be turned off for a period (couple of minutes), then when the car is turned back on it will test all the circuits - irrespective of whether the circuit is in use, so it will test the lights using a short pulse and log the fault if present.
(2) A few cars continually test the circuit and if all is OK they will re-enable the circuit.
(3) Some cars notice a fault and refuse to enable the circuit until the fault is cleared AND the fault is reset using diagnostics.

SO first things first, disconnect from ECU and test resistance of circuit - compare to the other side, this should be around 2-3ohms for a cold 5W bulb, it's 10 times greater for a hot filament just in case you are wondering abut ohms law.

Next find a friend with a LR capable diagnostics reader - not just a cheap OBDII one, and read any codes. Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner