Chart D: Data Circuit Problem
You have been directed to this chart as a result of a total loss of communication on circuit 800. This could be due to a wiring or element problem.
NOTE:
The following step numbers refer to circled numbers on diagnostic chart. See Fig 1
. For circuit identification, see Figure
.
- This step assures that the BCM and the 800 data circuit is asleep. If the 800 circuit is up and resistance is measured between ALDL pins L and M, the resistance reading will be erratic and incorrect.
- This step checks for a short to ground on circuit 800.
- The last two steps have established that circuit 800 is not open or shorted to ground. This step will check circuit 800 while it is operating. Normal operating voltage on circuit 800 is between .1 and 5 volts, fluctuating continuously.