C553

CRT Memory Circuit:

CIRCUIT DESCRIPTION:

Code C553 does not necessarily indicate a fault but is a normal occurrence anytime the power to the CRTC has been interrupted. This code could set if the system voltage drops below 8.0 volts at CRT terminal C1. Possible causes for this are:

^ Faulty charging system.
^ Faulty starter system.
^ Extreme cold weather.
^ Jump starting vehicle.

DIAGNOSIS:

Key off, backprobe CRT controller terminals C1 and C8. Note voltage at key-off, key-on, during crank, and with the engine running.

^ If voltage remains above 8.0 volts at all times, check for poor terminal contact. If code persists, replace CRT controller.
^ If voltage remains below 8.0 volts at all times, check for an open in circuit 801 and check for an open or short to ground on circuit 812.
^ If voltage goes below 8.0 volts at times, repair charging or starting system which is causing the low system voltage condition.