Test F - Engine Coolant Temp. (ECT) Sensor Test (Code 21)
- Start engine and run at 2000 RPM for 5 minutes. Check that upper radiator hose is hot and pressurized. Repeat Quick Test. If vehicle stalls, problem is not EEC related. If code 21 is not displayed, perform tests for other service codes (if any). If code 21 is still displayed, proceed with test.
- Disconnect ECT and inspect both connectors. Connect voltmeter positive lead to harness circuit 354 and negative lead to circuit 359. Turn ignition on and observe voltage. If voltage is greater than 6 volts, perform Reference Voltage Test. If voltage is less than 4 volts, proceed to step 5). If voltage is between 4 and 6 volts, proceed to step 3).
- Turn ignition off and wait 10 seconds. Measure resistance across ECT pins. If resistance is less than 1,300 ohms or more than 7,450 ohms, replace ECT sensor and repeat Quick Test. If resistance is between 1,300 and 7,450 ohms, proceed with test.
- Turn ignition off and wait 10 seconds. Run engine for 2 minutes. Measure resistance across ECT pins. If resistance is less than 1,550 ohms or more than 4,250 ohms, replace ECT sensor and repeat Quick Test. If resistance is between 1,550 and 4,250 ohms, replace processor and repeat Quick Test.
- Turn ignition off and wait 10 seconds. Disconnect processor and inspect both 60 pin connectors. Connect breakout box to harness and leave processor disconnected. Measure continuity of circuit 354 to breakout box pin 7 and circuit 359 to breakout box pin 46. If either resistance is more than 5 ohms, repair harness and repeat Quick Test. If both resistances are less than 5 ohms, proceed with test.
- Turn ignition off and wait 10 seconds. Measure resistance from breakout box pin 7 to breakout box pins 40 and 60. If either reading is 10,000 ohms or less, repair short circuit and repeat Quick Test. If both readings are more than 10,000 ohms, return to step 3).