2003 SPORT TRAC COMPUTER FAILING?
1121 Views 2 Replies Latest reply: 2019-10-24 05:27:54
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Level 1
(5) points
From one door open code to nineteen codes for functions that function properly one hour ago. No current spikes to the cmputer. I have tested with an ohm meter several components finding them in proper range. For instance the ac will not activate. Following back by schematic, there is no 5.0 volt power to the high or low pressure sensor, there is no 5.0 volt power to the ac clutch relay. I can however activate the clutch with my power probe. Too many things reported as malfunctions to be chance failures. What test can I perform to rule to rule computer failure in or out?
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Level 1
(3) points
Unplug every 5v sensor and then see if you get 5volts. It's possible that a bad sensor is pulling the 5v reference down. Also, with the negative battery terminal disconnected, check for continuity between the 5v reference and ground. You could have a chafed wire grounding out and pulling down the reference voltage.Are you sure the a/c clutch is only supposed to get 5 volts? Relays, solenoids, etc normally get 12 volts, sensors get 5 volts. -
Level 10
(7578) points
I myself would first look at the power train wiring diagrams, Unplug ECM connectors ,isolate and verify all the dedicated power and grounds to the ECM connectors all test good and are capable of carrying an electrical load momentarily by brightly illuminating a small halogen bulb used for circuit load testing purposes.
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