CONTROL GP-DISPLAY EPROM 1712087 - Caterpillar

Illustration 1 g03715932
Rear cover removed for clarity
(1) Evaporator sensor Diagnostics
Illustration 2 g03717766
Partial electrical schematic
(A) Connector
(B) Connector
(C) Connector
(D) Connector
(1) Evaporator sensor
Disconnect evaporator sensor (1) connector from connector (D). Measure the value of the resistance in the evaporator sensor. See "Specifications" for the correct resistance value. Proceed to Step 2.
If the resistance value is incorrect see, Step 3. If the resistance value is correct, see Step 4.
Replace the evaporator sensor.
Measure the voltage between the "GY/YL" wire and the "BK/YL" wire at connector (N). See "Specifications" for the correct voltage. Proceed to Step 5.
If the voltage value is incorrect, see Step 6. If the voltage value is correct, see Step 7.
Disconnect connector (C) from connector (B). Check the wiring harness between connector (D) and connector (C). Repair the wiring harness if faulty. Also, check the system power source. Refer to Systems Operation, "Air Conditioning System Electrical Schematic".
Reconnect the evaporator sensor connector to connector (D). Measure the voltage between "GY/YL" wire and the "BK/YL" wire at connector (B). See "Specifications" for the correct voltage. Proceed to Step 8.
If the voltage value is incorrect, see Step 9. If the voltage value is correct, see Step 10.
Disconnect connector (A) from the control panel. Check the wiring harness between connector (B) and connector (A). Repair the wiring harness if faulty.
Reconnect connector (C) to connector (B). Measure the voltage between the "GY/YL" wire and the "BK/YL" wire at the control panel. If the voltage value is incorrect, replace the control panel. Specifications
Illustration 3 g02316016
Evaporator sensor thermal characteristics
(R) Resistance (k Ohms)
(T) Temperature Resistance in the evaporator sensor 0 °C (32 °F) ... 1.645 kΩ 25 °C (77 °F) ... 5 kΩVoltage between connectors ... 5.0 VVoltage between terminals 10 °C (50 °F) ... 1.83 V 20 °C (68 °F) ... 1.34 V 25 °C (77 °F) ... 1.13 V 30 °C (86. °F) ... 0.96 V