OBD-II Question

I am having problems with my '99 Suburban and have had problems with my '98 Toyota so I bought the Harbor Freight OBD scanner, item number 98614. It works with my Toyota, but not the Suburban. It is supposed to be fully
compatible with '96 an up domestic and imports, but it obviously is not. The Suburban interface has pin 1 and 8 active, but the scanner tool does not have these connections. I suspect this might be the problem. Question, isn't this Suburban supposed to be OBD-II compliant by federal law? I want to make sure the problem is in the vehicle, not the scanner.
Mike D.
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Michael Dobony wrote:

The problem is probably the scan tool. However it is also possible that the Suburban falls outside the requirements of the OBDII standard if it isn't considered a light duty vehicle. That depends on the GVW of the vehicle (even then it is likely compliant if it has the connector)
This is the required spec for the connector.
1. Manufacturer discretion. GM: J2411 GMLAN/SWC/Single-Wire CAN. 2. Bus positive Line of SAE-J1850 PWM and SAE-1850 VPW 3. Ford DCL(+) Argentina, Brazil (pre OBD-II) 1997-2000, Usa, Europe, etc. 4. Chassis ground 5. Signal ground 6. CAN high (ISO 15765-4 and SAE-J2284) 7. K line of ISO 9141-2 and ISO 14230-4 8. - 9. - 10. Bus negative Line of SAE-J1850 PWM only (not SAE-1850 VPW) 11. Ford DCL(-) Argentina, Brazil (pre OBD-II) 1997-2000, Usa, Europe, etc. 12. - 13. - 14. CAN low (ISO 15765-4 and SAE-J2284) 15. L line of ISO 9141-2 and ISO 14230-4 16. Battery voltage
These are the current protocols you usually find.
SAE J1850 PWM (pulse-width modulation - 41.6 kB/sec, standard of the Ford Motor Company) o pin 2: Bus+ o pin 10: Bus o High voltage is +5 V o Message length is restricted to 12 bytes, including CRC o Employs a multi-master arbitration scheme called 'Carrier Sense Multiple Access with Non-Destructive Arbitration' (CSMA/NDA)
SAE J1850 VPW (variable pulse width - 10.4/41.6 kB/sec, standard of General Motors) o pin 2: Bus+ o Bus idles low o High voltage is +7 V o Decision point is +3.5 V o Message length is restricted to 12 bytes, including CRC o Employs CSMA/NDA
ISO 9141-2. This protocol has an asynchronous serial data rate of 10.4 kBaud. It is somewhat similar to RS-232, but that the signal levels are different, and that communications happens on a single, bidirectional line without extra handshake signals. ISO 9141-2 is primarily used in Chrysler, European, and Asian vehicles. o pin 7: K-line o pin 15: L-line (optional) o UART signaling (though not RS-232 voltage levels) o K-line idles high o High voltage is Vbatt o Message length is restricted to 12 bytes, including CRC
ISO 14230 KWP2000 (Keyword Protocol 2000) o pin 7: K-line o pin 15: L-line (optional) o Physical layer identical to ISO 9141-2 o Data rate 1.2 to 10.4 kBaud o Message may contain up to 255 bytes in the data field
ISO 15765 CAN (250 kBit/s or 500 kBit/s). The CAN protocol is a popular standard outside of the US automotive industry and is making significant in-roads into the OBD-II market share. By 2008, all vehicles sold in the US will be required to implement CAN, thus eliminating the ambiguity of the existing five signalling protocols. o pin 6: CAN High o pin 14: CAN Low
http://pinoutsguide.com/CarElectronics/gm_car_obd_ii_pinout.shtml
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Steve W.
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