PDP11/23+ Error code question

Another rescue from the works scrap pile.... I have an OEM 11/23 PLUS, which is based on a quad height chassis (H9875A?), with an 11/23+ cpu, two memory cards, and an RLV12 disk controller (there were a number of other cards, two DEQNA (dual ethernet installation), an OEM video interface, DLV11, and an OEM system ID card (this places a 4 bit octal value in a register that can be read via the bus). These cards have all been removed and replaced with grant cards). The system originally booted via ethernet, and the RLV12 was only installed for standalone diagnostics, hence the cut down version. When the unit is powered up, there is no output to the terminal, and the processor fault LED's give a code of 14, which is listed as "Scope Loop" - does anyone know what this signifies? I have set the boot switches to the factory test settings, with RL02 boot, and the SLU's are set to 9600. The other jumpers all appear to be correct. Thanks Jim. Please see our website the " Vintage Communication Pages" at WWW.G1JBG.CO.UK