LW4000 fault start wheel well

[grimestoppers]

We have another auto issue. Everything has been good up until this afternoon since our last issue. A car had its wash completed and left the wash . Roughly 5 seconds later, with auto 2 empty, the bay in use sign lit up and went out, then lit up and stayed on.
The printout inside said the fault was START WHEEL WELL. The circuit board readout said UNDERCARRIAGE EYE FAIL.
Is the fault potentially the positioning sensors for the car that are fixed to the wall at the end of the wash? It would be unlikely that it is the wheel washers sensor as they are separate from the car positioning for the wash, or am I incorrect. Both of these appear to have their wiring run into the shed, not actually part of the festoon wiring, is this correct.
What are your thoughts on this? I would greatly appreciate your feedback.

 

[PEI]

The Undercarriage Eye Fail is a separate issue from the Start Wheel Well. The Start Wheel Well is what has the bay shutdown. Originally this would have meant a faulty sensor on the Treadle, but it sounds like you have the Virtual Treadle. The most likely culprit is the set of yellow and black photo eyes mounted to the wall that serves to tell the customer where to stop. It will be the set closest to the entrance. If they are seeing one another and the receiver is seeing when they are blocked then the next thing to check would be the VT card inside the J0 cabinet.

 

[PEI]

The Undercarriage Eye Fail will cause the Undercarriage to come on as soon as the wash is fired. It's usually the photo eyes mounted on the wall just before the Undercarriage. There's also an amplifier located on the passenger side in the J2 box up by the rail.