AIR PUMP engine management light
12-10-2004, 03:32 PM
#11
Former Moderator
When the 1st failure is logged by the PCM, a temporary DTC is stored. The CEL is not on, at the time of the 2nd failure, the CEL is illuminated.
So if you start the car when is cold and it fails once, the temp is stored. Say you drive 30 minutes till the coolant temp is 190deg. you stop the car and and do something for 15 minutes. when you get back in the car the coolat temp is 180deg. The Air pump doesn't run, so the test doesn't run. You get to were you where going, and shut the car off. the car sits for 2 hours and then is restarted with a coolant temp of 110deg. The air pump runs, and the test fails. The CEL is turned on, even thhough you've driven the car 3 seperate times.
A complete trip is a cold start, warm up to operating temp, and a PCM power down. If the car doesn't get cold enough, or run long enough to warm up, the trip is not complete.
This is why it can take multiple actual trip to illuminate a "2 trip" DTC.
So if you start the car when is cold and it fails once, the temp is stored. Say you drive 30 minutes till the coolant temp is 190deg. you stop the car and and do something for 15 minutes. when you get back in the car the coolat temp is 180deg. The Air pump doesn't run, so the test doesn't run. You get to were you where going, and shut the car off. the car sits for 2 hours and then is restarted with a coolant temp of 110deg. The air pump runs, and the test fails. The CEL is turned on, even thhough you've driven the car 3 seperate times.
A complete trip is a cold start, warm up to operating temp, and a PCM power down. If the car doesn't get cold enough, or run long enough to warm up, the trip is not complete.
This is why it can take multiple actual trip to illuminate a "2 trip" DTC.
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