Need help!!! Car not seen by VAG tool
04-08-2008, 12:27 PM
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Need help!!! Car not seen by VAG tool
Battery went dead and replaced (jumpstarted car prior to that). After battery replacement, car wouldn't start. VAG tool can not detect the car. No CEL as well when ignition in on position. Looked at ECM power supply relay and that does not seem to work - replaced...still not starting. Thought maybe ECU is fried - borrowed a friend's ECU...still does not start. Don't know where else to look. Any help or leads would be appreciated.
04-08-2008, 12:39 PM
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If the CEL isn't on when the key is turned on, then it sounds like the ECU is dead or disconnected.
Trace the wiring from pin 7 in the diagnostic port to the appropriate pin on the ECU for the k-line. Also test the port to make sure you have power and ground:<ul><li><a href="http://www.ross-tech.com/vag-com/aftermarket-radio.html">http://www.ross-tech.com/vag-com/aftermarket-radio.html</a</li></ul>
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04-08-2008, 01:01 PM
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Re: If the CEL isn't on when the key is turned on, then it sounds like the ECU is dead or disconnect
And one more thing...the radio does not have any power to it either. Every other accessoriy seems to be fine. Will try your suggestion when i get home.
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04-08-2008, 06:41 PM
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No voltage seen on pin 7
Is there anything in the radio that may keep the ECU from being powered? Reason being is all other accessories are working except for the radio (won't power up)
04-08-2008, 10:24 PM
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Pin 7 is the "K" diagnosis line. Edited:
As per Ross-Tech, K line can have between 1 and 9 volts present but should not have +Batt 12vdc voltage at the Diagnostics Port pin T16/7. But, pin T16/7 must have continuity with all the other "K" line connections at other devices that use the "K" line for diagnostics, between T16/7 and the "K" line connection/pin terminal at each device. Pin T16/1 is swithched +vdc, circuit "15a", from the ignition switch, and pin T16/16 is unswitched +vdc, circuit "30". Pin T16/1 will be energized with the ignition key ON only, whereas pin T16/16 is energized all of the time. Therefore, there are two fused +12 vdc voltages. The first is at T16/1 (with the key ON,) and the other at T16/16 (unswitched "30").
Are you sure that there are no blown fuses?
There is no relationship between the engine ECU and the radio other than the "K" diagnostics line connection. The two fuses described above, may be also connected to several other devices via a seperate common connection for each fuse, in the wiring harnesss involved, (depending on specific vehicle model arrangement as equiped,) so, having several devices unpowered, points to a blown fuse associated with, and shared by those devices. Or, several fuses are blown.
Are you sure that there are no blown fuses?
There is no relationship between the engine ECU and the radio other than the "K" diagnostics line connection. The two fuses described above, may be also connected to several other devices via a seperate common connection for each fuse, in the wiring harnesss involved, (depending on specific vehicle model arrangement as equiped,) so, having several devices unpowered, points to a blown fuse associated with, and shared by those devices. Or, several fuses are blown.
04-09-2008, 05:07 AM
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Actually pin 7 should have between 1 and 9 volts. Check this page:
<ul><li><a href="http://www.ross-tech.com/vag-com/faq_4.html#4.3">http://www.ross-tech.com/vag-com/faq_4.html#4.3</a</li></ul>
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