B1318

CIRCUIT DESCRIPTION
The Sun Load sensor is a light sensitive photodiode that controls signal voltage to the Air Conditioning Programmer (ACM). This photodiode is different from standard thermistor sensors and resistance measurements will not produce accurate results. The ACM monitors the voltage on CKT 590 to the sensor. When the sensor is in direct light the ACM reads a low signal voltage at pin "C7." As the sensor becomes shaded, the signal voltage increases. Signal voltage will vary between 5V (open circuit) and 0V (short circuit).

TEST CONDITION(S)
1. Ignition "ON."

ACTION TAKEN
1. A substitute reading of 250 counts will be implemented to allow continued operation of the system.

TEST DESCRIPTION
1. Scan tool displays sun load sensor reading. jumpering the harness connector determines if the wiring or sensor is the cause.

NOTES ON INTERMITTENTS
If an intermittent DTC B1318 is being set connect Scan Tool, select ACM Data list, Open/Shorts Data and note reading.

Manipulate the wiring while observing scan tool. If failure is induced, the reading will jump. Check for poor terminal contact, obstructed, or defective sensor.