CANBUS electrical issues continued.
#1
CANBUS electrical issues continued.
I am currently trying to diagnose an electrical fault with a 2007 XKR.
Symptoms:
DSC and intermittent parking brake fault, followed by a whole host of faults (gearbox, abs, battery not charging, brake fluid low, cruise not available, heavy steering, struggle to get the engine to turn over, gets stuck in park, starting without pressing brake pedal, brake lights stuck on after getting out (ign off),
I measured the resistance between pins 6 and 14 (can high and can low) on the diagnostic port as 105.6 Ohms. (During fault condition)
Am I right in thinking this indicates one of the 120 Ohm resistors is 'missing', indicating a module containing one of the terminating resistor is faulty, or wiring fault in the circuit?
Which modules or wires contain a terminating resistor?
What are my next steps to locating the issue (will check feed and earth good.
Check each leg of wiring?
Symptoms:
DSC and intermittent parking brake fault, followed by a whole host of faults (gearbox, abs, battery not charging, brake fluid low, cruise not available, heavy steering, struggle to get the engine to turn over, gets stuck in park, starting without pressing brake pedal, brake lights stuck on after getting out (ign off),
I measured the resistance between pins 6 and 14 (can high and can low) on the diagnostic port as 105.6 Ohms. (During fault condition)
Am I right in thinking this indicates one of the 120 Ohm resistors is 'missing', indicating a module containing one of the terminating resistor is faulty, or wiring fault in the circuit?
Which modules or wires contain a terminating resistor?
What are my next steps to locating the issue (will check feed and earth good.
Check each leg of wiring?
Last edited by Gillsy; 09-17-2023 at 12:40 AM.
#2
Two 120 ohm terminating resistors on the bus would be 60 ohms as they are in parallel. How you would find the ends of the bus I dunno.
That's if they are in fact 120 ohm, which they probably are:
https://www.kmpdrivetrain.com/paddle...-tips-can-bus/
That's if they are in fact 120 ohm, which they probably are:
https://www.kmpdrivetrain.com/paddle...-tips-can-bus/
#4
Thanks, I guess I will unplug one of those control modules and measure resistance across CAN hi/low to check integrity of the loom (I should expect around 120 ohms back through the loom with 1 terminating control module unplugged?
I need to make a correction, my measured value was 105 Ohms so this would indicate high resistance on the bus?
I need to make a correction, my measured value was 105 Ohms so this would indicate high resistance on the bus?
#5
Thanks, I guess I will unplug one of those control modules and measure resistance across CAN hi/low to check integrity of the loom (I should expect around 120 ohms back through the loom with 1 terminating control module unplugged?
I need to make a correction, my measured value was 105 Ohms so this would indicate high resistance on the bus?
I need to make a correction, my measured value was 105 Ohms so this would indicate high resistance on the bus?
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Sean W (09-17-2023)
#6
In your previous post on the same topic, you noted that you had:
C1D15-64 intermittent brake switch status
C1803-00 intermittent motor disengage full travel distance not reached upon release
Did you fix these? You also asked if there were resistors in any modules and of course there are, but specific to those codes, there is a variable resistor in the park brake actuator. The actuator doesn't use HS CAN but the park brake switch does - both feed off the Park brake Module. I don't see the connection (no pun intended) but confirm you're fixing codes before moving on and also consider aging the moderator to merge the two threads.
C1D15-64 intermittent brake switch status
C1803-00 intermittent motor disengage full travel distance not reached upon release
Did you fix these? You also asked if there were resistors in any modules and of course there are, but specific to those codes, there is a variable resistor in the park brake actuator. The actuator doesn't use HS CAN but the park brake switch does - both feed off the Park brake Module. I don't see the connection (no pun intended) but confirm you're fixing codes before moving on and also consider aging the moderator to merge the two threads.
The following users liked this post:
McJag222 (09-17-2023)
#7
In your previous post on the same topic, you noted that you had:
C1D15-64 intermittent brake switch status
C1803-00 intermittent motor disengage full travel distance not reached upon release
Did you fix these? You also asked if there were resistors in any modules and of course there are, but specific to those codes, there is a variable resistor in the park brake actuator. The actuator doesn't use HS CAN but the park brake switch does - both feed off the Park brake Module. I don't see the connection (no pun intended) but confirm you're fixing codes before moving on and also consider aging the moderator to merge the two threads.
C1D15-64 intermittent brake switch status
C1803-00 intermittent motor disengage full travel distance not reached upon release
Did you fix these? You also asked if there were resistors in any modules and of course there are, but specific to those codes, there is a variable resistor in the park brake actuator. The actuator doesn't use HS CAN but the park brake switch does - both feed off the Park brake Module. I don't see the connection (no pun intended) but confirm you're fixing codes before moving on and also consider aging the moderator to merge the two threads.
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#10
Thanks for the suggestions. I'm fairly sure the specific parking brake codes have not appeared again, I had assumed this isolated incident was a symptom rather than a cause.
By 'kicking nodes off the network' I take it this would be a case of unplugging modules one by one to see if the network returns to 60 Ohms (across can hi/low)?
If my problem lies with the instrument cluster I guess I'd be looking for 120 Ohms unplugged?
By 'kicking nodes off the network' I take it this would be a case of unplugging modules one by one to see if the network returns to 60 Ohms (across can hi/low)?
If my problem lies with the instrument cluster I guess I'd be looking for 120 Ohms unplugged?
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