Light Output Reduction

Reducing the light output of individual control modules is a convenient method of determining the area of a defect.

• Switch on the radio.
• In Control Module functions, begin to activate luminous power reduction in the individual control module. (In this test the light output of the selected control module is reduced for 5 seconds and then automatically reset to normal output)
• If the optical transmission for control module A to the next control module in the ring (control module B) is OK, a slight noise may occur when the light output is reduced, however the radio will continue to play.
• If the radio goes off and comes back on again (radio volume may be reduced) in 5 to 10 seconds, the optical transmission between control modules A and B is defective.

If the visual inspection is OK, the fault can be located using the OPPS tester or optionally performing the following tests.

• Remove the input optical wave guide from control module B and confirm the presence of light.
• If light is present, install by-pass optical wave guide in place of control module A, clear fault codes in module B. If MOST network operates properly, then control module A is at fault and must be replaced.
• If MOST network still has a fault, put module A back in the network and by-pass module B. Clear faults.
• If MOST network operates now problem is with control module B and it must be replaced.
• If light is not present at input of module B, perform ring break diagnostics.