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techtalk:evo:elec04 [2018/05/14 00:21] ixl2relax [CANbus - Controller Area Network Bus] |
techtalk:evo:elec04 [2018/05/14 00:29] ixl2relax [CANbus - Controller Area Network Bus] |
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| + | **Test - CANbus normal voltage:**\\ | ||
| + | With the keyswitch on, you can connect a meter (set for 20v readings) between Pin#1 (White/Red), or Pin#3 (White/Black), and ground to test for the 2.5v, which would be a normal reading on these lines. | ||
| - | Test - CANbus shorted together: | + | **Test - CANbus shorted together:**\\ |
| You can test the CANbus to see if the two lines are shorted together. With the __keyswitch off__, place your meter on the ohms scale, and put one probe each on the DLC Pin#1 (White/Red) and DLC Pin#3 (White/Black). You should read 60-ohms between these CANbus High and CANbus Low connections. If the resistance is less than 50-ohms, you will want to disconnect devices on the CANbus, one at a time, to see which is causing the low reading. Devices should be removed in the following order: Speedometer, ECM, LftHandControl, RtHandControl, Tach and BCM. | You can test the CANbus to see if the two lines are shorted together. With the __keyswitch off__, place your meter on the ohms scale, and put one probe each on the DLC Pin#1 (White/Red) and DLC Pin#3 (White/Black). You should read 60-ohms between these CANbus High and CANbus Low connections. If the resistance is less than 50-ohms, you will want to disconnect devices on the CANbus, one at a time, to see which is causing the low reading. Devices should be removed in the following order: Speedometer, ECM, LftHandControl, RtHandControl, Tach and BCM. | ||
| - | Test - CANbus High shorted ground: | + | **Test - CANbus High shorted ground:**\\ |
| You can test to see if the CANbus High signal line, DLC Pin#1 (White/Red) is shorted to ground. With the __keyswitch off__, place your meter on the ohms scale, and put one probe on the DLC Pin#1 (White/Red) and the other on ground. You should read more than 1000-ohms to ground. If the resistance is less than 1000-ohms, you will want to disconnect devices on the CANbus, one at a time, to see which is causing the low reading. Devices should be removed in the following order: Speedometer, ECM, LftHandControl, RtHandControl, Tach and BCM. If the low reading does not go away, you will need to examine your wiring for the problem. | You can test to see if the CANbus High signal line, DLC Pin#1 (White/Red) is shorted to ground. With the __keyswitch off__, place your meter on the ohms scale, and put one probe on the DLC Pin#1 (White/Red) and the other on ground. You should read more than 1000-ohms to ground. If the resistance is less than 1000-ohms, you will want to disconnect devices on the CANbus, one at a time, to see which is causing the low reading. Devices should be removed in the following order: Speedometer, ECM, LftHandControl, RtHandControl, Tach and BCM. If the low reading does not go away, you will need to examine your wiring for the problem. | ||
| - | Test - CANbus Low shorted power: | + | **Test - CANbus Low shorted power:**\\ |
| You can test to see if the CANbus Low signal line, DLC Pin#3 (White/Black) is shorted to a power line. With the __keyswitch off__, place your meter on the 20v scale, and put your RED probe on the DLC Pin#3 (White/Black) and the other on ground. You should read 0-volts to ground. If the reading is more than 0-volts, you will want to disconnect devices on the CANbus, one at a time, to see which is causing the voltage reading. Devices should be removed in the following order: Speedometer, ECM, LftHandControl, RtHandControl, Tach and BCM. If the voltage reading does not go away, you will need to examine your wiring for the problem. | You can test to see if the CANbus Low signal line, DLC Pin#3 (White/Black) is shorted to a power line. With the __keyswitch off__, place your meter on the 20v scale, and put your RED probe on the DLC Pin#3 (White/Black) and the other on ground. You should read 0-volts to ground. If the reading is more than 0-volts, you will want to disconnect devices on the CANbus, one at a time, to see which is causing the voltage reading. Devices should be removed in the following order: Speedometer, ECM, LftHandControl, RtHandControl, Tach and BCM. If the voltage reading does not go away, you will need to examine your wiring for the problem. | ||
| - | Test - CANbus High shorted to power: | + | **Test - CANbus High shorted to power:**\\ |
| - | You can put a meter between Pin#1 (White/Red) or Pin#3 (White/Black) and ground to test for the 2.5v that would be normal on these lines. | + | With the keyswitch on, you can connect a meter (set for 20v readings) between Pin#1 (White/Red) and ground. If the voltage is higher than 4v on CANbus High, you may have a short to voltage somewhere. By turning the keyswitch off, then removing one component from the CANbus, then turning the keyswitch back on, you can test to see if the voltage on DLC Pin#1 has normalized because you removed a malfunctioning CANbus component. Devices should be removed in the following order: Speedometer, ECM, LftHandControl, RtHandControl, Tach - If DLC Pin#1 has not normalized, then, with the keyswitch off, reconnect the ECM & disconnect power to the BCM, then disconnect the main connector from the BCM, then turn the keyswitch on and test the DLC pin again - If now normalized, the BCM is suspect. |
| - | + | ||
| - | If the voltage is higher than 4v on CANbus High, you may have a short to voltage somewhere. By turning the keyswitch off, then removing one component from the CANbus, then turning the keyswitch back on, you can test to see if the voltage on DLC Pin#1 has normalized by removing a bad CANbus component. Devices should be removed in the following order: Speedometer, ECM, LftHandControl, RtHandControl, Tach - If DLC Pin#1 has not normalized - With the keyswitch off, reconnect the ECM & disconnect power to the BCM, then disconnect the main connector from the BCM, then turn the keyswitch on and test the DLC pin again - If now normalized, the BCM is suspect. | + | |
