Chart A No Display on CCP

CIRCUIT DESCRIPTION

The ECC Head is powered by system voltage from the battery by CKT 5OA through the 20 Amp A/C Fuse, and is ground by CKT 155B. It also receives battery voltage through CKT 140C. This power is internally utilized for control purposes as well as for display purposes. If either of these circuits becomes open, the ECC Head will be unable to function, resulting in a blank display on the Climate Control Panel.


TEST DESCRIPTION

Numbers below refer to circled numbers on the diagnostic chart.

1. If the A/C or Stop-Haz Fuse is blown, the ECC Head will not receive its voltage supply,resulting in a blank display. If a fuse is blown there must be a short to ground in CKT 50 or CKT 140.

2. If there is an open in the CKT 50 wiring, the display will be blank. This can be checked by measuring voltage from pin H of the ECC Head to ground.

3. If there is an open in the CKT 140 wiring, the display will be blank. This can be checked by measuring voltage from pin 1 of the ECC Head to ground.

4. If there is an open in the CKT 155 wiring, the display will be blank. This can be checked by measuring voltage between pin 1 and 5 of the ECC Head.

5. If the ECC connector is loose or the ECC Head is internally damaged, the display will be blank.