2004 Chev Tahoe Case Study No Communication

2004 Chevrolet Tahoe -No Generic
2004 Chevrolet Tahoe
This vehicle was located at
Sullivan Pontiac Buick.
The concern was that the vehicle
would communicate with the
TECH 2 scantool, but would not
communicate with APPLUS
2004 Chevrolet Tahoe
2004 Chevrolet Tahoe
2004 Chevrolet Tahoe
2004 Chevrolet Tahoe
The first step is to review
communication schematics for the
vehicle you are working on.
This is a Class 2 communication
SP205 Schematic Part I
SP205 Schematic Part II
Splice Pack 205
Spice Pack 205-Connector Endview
2004 Chevrolet Tahoe
The second step is to scope the
Class 2 line.
A BOB was attached to the vehicle
at the DLC.
The scope probes were placed in
Pin # 2 on the BOB.
Class 2 level was below threshold.
Class 2 Level below Threshold
The class 2 level
was too low.
2004 Chevrolet Tahoe
The third step was to take the comb
out of the splice pack and jumper
each module line.
Every terminal on the SP205 was at
threshold except pin# H
Class 2 Level at Threshold
This was the voltage level
at all pins except pin# H.
SP205 Schematic Part II
Class 2 Level below Threshold
This was the voltage
level denoted at pin# H.
Terminal H was backed out of the
SP205 connector and
communication was restored on
this vehicle at a generic level.
A loading effect is taking place on
this circuit per a wiring or module
related issue.
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