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Self test - capability and lack thereof Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Mon, 18 Feb 2008 09:48:54
In Reply to: That's about what I figure, Noel, Mon, 18 Feb 2008 06:01:31 Members do not see ads below this line. - Help Keep This Site Online - Signup |
On the ACCI system, the servo had an internal position feedback system, so the ACC could tell if the servo was moving. Of course, if the servo arm fell off, the ACC would come back with no faults because the servo was running.
On ACCII, there is no direct feedback system. It's a stepper motor, not an DC motor like ACCI. I'll have to check my ACC manual, but the self test can only tell if the motor is moving by seeing if the temperature downstream of the mixing flap changes when the motor is commanded to move. So if the car is cold - the heater core and the outside air temp are pretty much the same - the self-test can't tell if the system is working - it also can't tell that it ISN'T working. So you won't get a fault with a cold engine. No guarantee that it will detect a fault with a hot engine- I'll have to see what the manual says. But I don't see a way to detect a motor fault with a cold engine, given the sensor suite.
posted by 192.249....
, Mon, 18 Feb 2008 09:48:54 <-- Viewing This Message, Tue, 19 Feb 2008 16:57:29
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