mmr36
New Member
Posts: 8
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Post by mmr36 on Oct 1, 2023 14:58:26 GMT
Hi all,
Looking to confirm the meaning of results in live data outputs in module 3C Lane change assistant Right.
In some of the live data outputs, the terms master and slave are used to describe the radars and other outputs assist 1 or assist 2 is used.
I'm assuming assist 1 refers to the Master and assist 2 refers to the Slave. (this is the case in other tools).
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Post by dv52 (Australia) on Oct 1, 2023 21:07:48 GMT
mmr36 : Hi. Excellent question- thanks for asking!!
It all starts with the topology of the CAN network on a mk7/7.5 - which I show diagrammatically in the top part of the picture below.
VW radically altered the CAN network on the Golf with the introduction of the Mk7 (which was the first model that had a MQB platform build). Because of the increasing complexity and number of control modules, the mk7 has 5 x distinct CAN buses which together make-up the CAN network on the vehicle. These individual CAN buses are separated on functional lines. Without making this reply a master class on CAN network structures- the pertinent part of the upper diagram below for the purpose of your question is the Extended CAN bus. This is where the modules for the Driver Assist systems on a mk7/7.5 reside - including Lane Change Assist (LCA).
The diagram below also shows the ancillary communication systems - the Diagnostic CAN bus that OBD11 uses ("J533" is the control unit that OBD11 calls the Gateway module) and the multiple LIN devices in the car which are low-speed, single-wire sensors/peripherals
I've shown the functional schematic for LCA in the lower part of my diagram below. It has 2 x separate control modules which are fitted behind the rear bumper cover in the mk7/7.5. The wiring diagram calls these modules J769 and J770. Each control unit is responsible for monitoring one side of the vehicle or adjacent lane and each module consists of a central processor unit and a radar sensor.
J769 monitors the right-hand side of the vehicle and OBD11 reports this module as 3C Lane Change Assistant Right Notice that of the 2 x modules, J769 is the only one that has a direct connection to the Extended CAN bus - this is the master control unit for the LCA function.
J770 monitors the left-hand side of the vehicle and OBD11 reports this module as CF Lane Change Assistant Left. J770 is the slave control unit because it communicates with the Extended CAN bus via the master control unit (through a private CAN bus). J770 is also responsible for activating both LCA warning lamps in the door mirrors.
Don
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mmr36
New Member
Posts: 8
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Post by mmr36 on Oct 2, 2023 1:14:30 GMT
Hi Don,
Thanks very much for replying, very helpful. As part of a recent retrofit, the auto radar calibration failed, I therefore need to remove the bar and adjust the position (angle) of Assist 1 as it is out of calibration range. Very helpfully, the output test gives me the precise angle to move it and I'll kick off auto calibration again.
MM
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mmr36
New Member
Posts: 8
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Post by mmr36 on Apr 5, 2024 7:24:06 GMT
Quick update since Don's assist, took a while to find some time to get to addressing the angle(s) of the radars (rear bumper off etc), but sorted now and the units are now recalibrating and progressing well. (resetting the master was a little tricky given the radars are MQB on an R36, shout out to Kamold for the assist).
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