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Case Study. 2004 Chevrolet Tahoe -No Generic Communication. 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 equipment. 2004 Chevrolet Tahoe.
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Case Study 2004 Chevrolet Tahoe -No Generic Communication
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 equipment.
2004 Chevrolet Tahoe • The first step is to review communication schematics for the vehicle you are working on. • This is a Class 2 communication protocol.
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.
Class 2 Level below Threshold This was the voltage level denoted at pin# H.
Summary • 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.