PTEN_0321 - 36
major challenges.
Since the circuit under test is a parallel
circuit created by two 120 ohm terminating resistors, a normal reading should be
around 60 ohms. If it's not, you'll need to
pare down the network and isolate. Keep
in mind that if you have an intermittent
problem, you can try performing wiggle
tests on circuit connections while monitoring your DVOM. In most cases, the
scan tool, DVOM, and wiring diagram
should provide everything needed to
address network challenges. There are
other tools still that might also provide
additional assistance. If you work on GM
vehicles, the Data Bus Diagnostic Tool
(see figure 2) application from General
Motors can be useful, as it provides a
deeper level of network intelligence.
The oscilloscope is another useful tool,
but you'll want to make sure the scope
you choose is fast enough to sample and
acquire data for bit level analysis. If your
scope isn't fast enough, you can still make
a few useful observations. One would be to
ensure that both CAN-Hi and CAN-Low
mirror each other. (See figure 3)
Picoscope also provides serial decoding tools that might prove to be helpful as
shown in the case study below.
Figure 1 - 64-bit CAN Payload
Figure 2 - GM Data Bus Diagnostic Tool
CASE STUDY
A 2014 Corvette came in for a wheel
alignment. As part of the post alignment process, the SAS (steering angle
sensor) required a reset/relearn. As
soon as we performed the reset, warning lights appeared on the dash. The
PSCM reported U0428 as current. A
U0428 indicates that the PSCM has
received invalid data from the steering
wheel angle sensor. With the scan tool
monitoring PSCM data, the SAS always
reported zero. When we logged into the
EBCM, SAS reported approximately 187
degrees with the wheels pointed straight
ahead and would change linearly as the
wheel was turned in either direction.
At this point, I was baffled as to why the
steering angle sensor failed. After review-
36
PTEN
MARCH 2021
www.VehicleServicePros.com
Figure 3 - High-speed CAN
Figure 4 - SAS Status Byte - defective sensor
http://www.VehicleServicePros.com
PTEN_0321
Table of Contents for the Digital Edition of PTEN_0321
Editor's Note
Featured New Products
Tool Briefing
Tool Reviews
Diagnostic Tech
Category Spotlight
Marketplace
Big-Time Boxes
PTEN_0321 - 1
PTEN_0321 - 2
PTEN_0321 - 3
PTEN_0321 - 4
PTEN_0321 - 5
PTEN_0321 - 6
PTEN_0321 - 7
PTEN_0321 - Editor's Note
PTEN_0321 - Featured New Products
PTEN_0321 - 10
PTEN_0321 - 11
PTEN_0321 - 12
PTEN_0321 - 13
PTEN_0321 - 14
PTEN_0321 - 15
PTEN_0321 - 16
PTEN_0321 - 17
PTEN_0321 - 18
PTEN_0321 - 19
PTEN_0321 - 20
PTEN_0321 - RSC1
PTEN_0321 - RSC2
PTEN_0321 - 21
PTEN_0321 - 22
PTEN_0321 - 23
PTEN_0321 - 24
PTEN_0321 - 25
PTEN_0321 - Tool Briefing
PTEN_0321 - 27
PTEN_0321 - 28
PTEN_0321 - 29
PTEN_0321 - Tool Reviews
PTEN_0321 - 31
PTEN_0321 - 32
PTEN_0321 - 33
PTEN_0321 - Diagnostic Tech
PTEN_0321 - 35
PTEN_0321 - 36
PTEN_0321 - 37
PTEN_0321 - Category Spotlight
PTEN_0321 - 39
PTEN_0321 - 40
PTEN_0321 - 41
PTEN_0321 - 42
PTEN_0321 - 43
PTEN_0321 - 44
PTEN_0321 - Marketplace
PTEN_0321 - Big-Time Boxes
PTEN_0321 - 47
PTEN_0321 - 48
PTEN_0321 - 49
PTEN_0321 - 50
PTEN_0321 - 51
PTEN_0321 - 52
PTEN_0321 - 53
PTEN_0321 - 54
PTEN_0321 - 55
PTEN_0321 - 56
PTEN_0321 - 57
PTEN_0321 - 58
PTEN_0321 - 59
PTEN_0321 - 60
PTEN_0321 - 61
PTEN_0321 - 62
PTEN_0321 - 63
PTEN_0321 - 64
PTEN_0321 - 65
PTEN_0321 - 66
PTEN_0321 - 67
PTEN_0321 - 68
PTEN_0321 - 69
PTEN_0321 - 70
PTEN_0321 - 71
PTEN_0321 - 72
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/december-2023
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/october-2023
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/september-2023
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/august-2023
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/july-2023
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/june-2023
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/may-2023
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/april-2023
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/march-2023
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/february-2023
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/december-2022
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/october-2022
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/september-2022
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/august-2022
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/july-2022
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/june_2022
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/2022scantoolspecguide
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/may_2022
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/april_2022
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/march-2022
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/february_2022
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/december-2021
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/october_2021
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/september_2021
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/pten_0821
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/pten_0721
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/scantoolspecguide2021
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/pten_0621
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/lift_guide_2021
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/may_2021
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/professional_tool_and_equipment_news_april_2021
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/pten_0321
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_February_2021
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_December_2020
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_October_2020
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_September_2020
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_August_2020
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_July_2020
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_and_Equipment_News_June_2020
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_May_2020
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_April_2020
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_March_2020
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_February_2020
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_December_2019
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_Octoberr_2019
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_September_2019
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_August_2019
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_July_2019
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_June_2019
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_May_2019
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/Professional_Tool_And_Equipment_News_April_2019
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/PTEN_0319
https://www.nxtbook.com/endeavor/professionaltoolandequipmentnews/PTEN_0219
https://www.nxtbookmedia.com