Insufficient engine coolant temperature for closed loop fuel control
After engine start-up, the elapsed time before feedback operation is initiated is too long [Engine Coolant Temperature (ECT) sensor input is insufficient for closed loop operation
• Poor connections between ECT and ECM
• Faulty ECTS
1. With ignition off, disconnect connector from ECTS and connector from ECM. Measure resistance between ECTS pin 1 and ECM 78 (less than 1 ohm). Is resistance less than 1 ohm?
Yes Go to step 2.
No Locate source of high resistance between ECTS pin 1 and ECM pin 78. Repair as necessary.
2. Remove ECT from engine. Measure resistance across terminals per chart "B". Are resistance measurements within specification?
· - 6 degrees F = 16.2 k ohms +/- 10%
· 68 degrees F = 2.45 k ohms +/- 10%
· 176 degrees F = 0.322 k ohms +/- 10%
Yes Thoroughly check for loose, bent or corroded terminals between ECT and ECM.
No Replace ECT.
3. Clear codes and verify any repairs by driving vehicle while monitoring ECT and Fuel Stat 1 in user data list with SCAN TOOL. Refer to chart "A" for amount of time in which Fuel Stat 1 should show closed loop operation after engine has been started. (Get start-up temperature by accessing user data with ignition key on and engine off before starting vehicle...
Tuesday, December 23rd, 2008 AT 2:45 AM