PicoScope 7 Automotive
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2007 range rover CAN bus waveform disruption
2007 range rover CAN bus waveform disruption
Can anybody shed any light on CAN H and CAN L wave forms, especially in frame 29. just looking for an answer for what might cause such disruption on the lines
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- Land Rover_Range Rover Sport_2007_20180803-0001.psdata
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Steve Smith
- Pico Staff Member
- Posts: 1586
- Joined: Sun Aug 25, 2013 7:22 am
Re: 2007 range rover CAN bus waveform disruption
Hello and thank you for the post.
This waveform (buffer 29) demonstrates the beauty of Fault Tolerant CAN in action
Using the math channel A-B we can see how the disruption to the CAN signal will still decode and the Physical Layer (0-2 V) to remain intact.
What we can be sure of is the event is "felt" in both CAN wires and the CAN threshold voltages return to normal (2.5 V)
The momentary disruption to the uniform can signal appears to be similar in time for each event (approx 53 micro seconds)
Would it be possible to introduce another channel looking for a high frequency current consumer
My line of thinking here is we have interference from a momentary event caused by a consumer.
We could use a current clamp around the battery positive cable whilst switching on consumers or road testing the vehicles.
Here we are looking for a correlation between current spikes and the disruption to CAN
Could we then place a current clamp around the CAN wiring where you have captured this event?
Could we also look for areas where the CAN wiring may have been modified or exposed?
Not sure if JLR utilse CAN for their trailer hitch but this could be an offender if the tow bar etc has been removed or wiring exposed.
Finally using the CAN Topology (and where access allows) if the fault is repeatable can we disconnect those CAN modules not containing termination resisters?
This could help locate a potential CAN node error
Have you any recorded codes for multiple modules reporting loss of communication with one module in particular?
I hope this helps, take care......Steve
This waveform (buffer 29) demonstrates the beauty of Fault Tolerant CAN in action
Using the math channel A-B we can see how the disruption to the CAN signal will still decode and the Physical Layer (0-2 V) to remain intact.
- CAN Disruption
The momentary disruption to the uniform can signal appears to be similar in time for each event (approx 53 micro seconds)
Would it be possible to introduce another channel looking for a high frequency current consumer
My line of thinking here is we have interference from a momentary event caused by a consumer.
We could use a current clamp around the battery positive cable whilst switching on consumers or road testing the vehicles.
Here we are looking for a correlation between current spikes and the disruption to CAN
Could we then place a current clamp around the CAN wiring where you have captured this event?
Could we also look for areas where the CAN wiring may have been modified or exposed?
Not sure if JLR utilse CAN for their trailer hitch but this could be an offender if the tow bar etc has been removed or wiring exposed.
Finally using the CAN Topology (and where access allows) if the fault is repeatable can we disconnect those CAN modules not containing termination resisters?
This could help locate a potential CAN node error
Have you any recorded codes for multiple modules reporting loss of communication with one module in particular?
I hope this helps, take care......Steve
Re: 2007 range rover CAN bus waveform disruption
Is it possible to affirm. that the algorithms of different ECU are the same as the PICO algorithm?
If the PICO recoded correctly, then it is not necessary that the ECU also recode similarly.
Different ECU will be differently sensitive to distortions
.
Here is an example of how a ECU can accept blocks :
If the PICO recoded correctly, then it is not necessary that the ECU also recode similarly.
Different ECU will be differently sensitive to distortions
.
Here is an example of how a ECU can accept blocks :
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Re: 2007 range rover CAN bus waveform disruption
Fully agree kona, no way that waveform made it in the car network can.
I would look for xenon retrofit kits, I would try run without dynamo, is it an aftermarket spark coil or even radio fitted?
Whats been changed recently to the car? What faultcodes appear on can bus?
I would look for xenon retrofit kits, I would try run without dynamo, is it an aftermarket spark coil or even radio fitted?
Whats been changed recently to the car? What faultcodes appear on can bus?
Re: 2007 range rover CAN bus waveform disruption
I am with liviu on chineeezium retro fit lighting of any kind. Even COB bulbs can play havoc with CAN lines! 
Anything non original is always the first point of suspicion nowadays.
Kev.
Anything non original is always the first point of suspicion nowadays.
Kev.
Re: 2007 range rover CAN bus waveform disruption
Thank you for all your replies. I'll actually be looking at the car again tomorrow so will check out all mentioned items.
I've added a math line (A-B) to the screen and I actually have a 2 volt differential majority of the time but very sporadically there are 3 volt spikes in the maths wave form, my knowledge on this certainly needs work! Is that enough to cause my intermittent no comms? (Sorry haven't got the file on this device)
I've added a math line (A-B) to the screen and I actually have a 2 volt differential majority of the time but very sporadically there are 3 volt spikes in the maths wave form, my knowledge on this certainly needs work! Is that enough to cause my intermittent no comms? (Sorry haven't got the file on this device)
Re: 2007 range rover CAN bus waveform disruption
Forgot to mention the 3 volt spikes were on another waveform taken when driving down the road. So far I've tried unplugging a lot of the modules on the network, still got a few left to go. I've also tried removing the alternator main lead as well
Re: 2007 range rover CAN bus waveform disruption
Sorry Steve I managed to completely miss your reply when scrolling through, unfortunately I can't add a 3rd wave form as yet as mine is only 2 channel. (My motorcycle is funny enough up for sale as I want the money to order 4 channel advanced kit)
That's a real thorough process you've given me, thank you, sounds as though I need the 4 ch a bit sooner than planned
That's a real thorough process you've given me, thank you, sounds as though I need the 4 ch a bit sooner than planned
Re: 2007 range rover CAN bus waveform disruption
Range Rover Sport
Reg: AK57 ZRC
Intermittent fault codes (after a couple of mins driving):
U0100-87: lost comms with PCM
U0101-87: lost comms with transmission control module
U0155-87: lost comms with instrument cluster control module
Permanent codes:
P0630-00 VIN not programmed or incompatible-engine control module-powertrain control module
P0902-00: Clutch actuator- circuit low
Only customer complaint: error on dash 'transmission range change unavailable'
we replaced the transfer box control module as there was a lot of corrosion present in the connector.
So today I've been down the road in the car with the Pico connected and captured the data as the error message appeared on the dash, quite a lot of time on the screen which i presume is not ideal for what i'm doing but didn't want to miss the error.
I've attached the file with a maths line A-B, some points the voltage difference is over 3 volts, is this enough to cause the intermittent no comms codes?
Am i approaching this the wrong way, should i be worrying more about the Clutch actuator code rather than the comms codes?
Reg: AK57 ZRC
Intermittent fault codes (after a couple of mins driving):
U0100-87: lost comms with PCM
U0101-87: lost comms with transmission control module
U0155-87: lost comms with instrument cluster control module
Permanent codes:
P0630-00 VIN not programmed or incompatible-engine control module-powertrain control module
P0902-00: Clutch actuator- circuit low
Only customer complaint: error on dash 'transmission range change unavailable'
we replaced the transfer box control module as there was a lot of corrosion present in the connector.
So today I've been down the road in the car with the Pico connected and captured the data as the error message appeared on the dash, quite a lot of time on the screen which i presume is not ideal for what i'm doing but didn't want to miss the error.
I've attached the file with a maths line A-B, some points the voltage difference is over 3 volts, is this enough to cause the intermittent no comms codes?
Am i approaching this the wrong way, should i be worrying more about the Clutch actuator code rather than the comms codes?
- Attachments
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- Land Rover_Range Rover Sport_2007_driving.psdata
- (22.25 MiB) Downloaded 705 times
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Steve Smith
- Pico Staff Member
- Posts: 1586
- Joined: Sun Aug 25, 2013 7:22 am
Re: 2007 range rover CAN bus waveform disruption
Thank you for the posts and feedback
I would most certainly focus on the customers symptom "Transmission Range Change Unavailable"
This is an error on the dash, is this also a symptom with the vehicle?
I.e. Can the transmission range be changed?
The fault code P0902-00 was this present before the Transfer box control module was replaced?
Can you confirm P0902-00 remains present with the new transfer box module installed and the same error message appear on the dash?
If so, does this code re-appear after clearing when driving a short distance?
If so I would not focus on CAN at this stage as your CAN error codes informing of communication failure may have been brought on by characteristic module behavior when fault codes are stored.
A typical example is an ABS code appears due to a wheel speed sensor fault. Here the ABS module may then drop communication with engine and transmission control modules so generating CAN communication codes.
Forgive me here as my JLR product knowledge is lacking for sure, but based on my experience with other scan tools, can you determine the Time Stamp or Occurrence order of the above codes?
This may help to determine is P0902-00 is triggered first, followed by communication codes etc.
Your approach with diagnosis here is fine as you are gathering evidence but I feel from the fault description our CAN issues might be consequence and not cause at this stage.
I hope this helps, take care........Steve
I would most certainly focus on the customers symptom "Transmission Range Change Unavailable"
This is an error on the dash, is this also a symptom with the vehicle?
I.e. Can the transmission range be changed?
The fault code P0902-00 was this present before the Transfer box control module was replaced?
Can you confirm P0902-00 remains present with the new transfer box module installed and the same error message appear on the dash?
If so, does this code re-appear after clearing when driving a short distance?
If so I would not focus on CAN at this stage as your CAN error codes informing of communication failure may have been brought on by characteristic module behavior when fault codes are stored.
A typical example is an ABS code appears due to a wheel speed sensor fault. Here the ABS module may then drop communication with engine and transmission control modules so generating CAN communication codes.
Forgive me here as my JLR product knowledge is lacking for sure, but based on my experience with other scan tools, can you determine the Time Stamp or Occurrence order of the above codes?
This may help to determine is P0902-00 is triggered first, followed by communication codes etc.
Your approach with diagnosis here is fine as you are gathering evidence but I feel from the fault description our CAN issues might be consequence and not cause at this stage.
I hope this helps, take care........Steve