Anomaly Chart

Control #	Date Added	Problem being addressed	Protocol if Available	Year / Make and any other identifying info, if important	Solution or work around	Result  or reference to Result
1	4/13/09	Incorrect physical address assignments. SAE 2178-1, Table 11, defines suggested ranges for physical address assignments for the different controllers (e.g., $10-17 for engine, $18-1F for transmission) on a vehicle to be used  in the header bytes of all SAE J1979 emission-related messages. However, ARB has not required manufacturers to adhere to these suggested ranges.	SAE 2178-1	?	Scan tool manufacturers should not and cannot try to reject, filter, or otherwise assign priorities to messages received from a vehicle based solely on the hex value of the physical address (e.g., assuming the controller with the lower numeric address value must be the engine controller is incorrect, etc.).
2	4/13/09	Incorrect header bytes. Some vehicles respond to scan tool J1979 request messages with improper header bytes. For example, depending on the protocol, a scan tool request message header (as defined in Figure 1 of J1979) is a "68 (or 61) 6A Fx". Vehicles are required to respond with header bytes of "48 (or 41) 6B addr". Some vehicle manufacturers incorrectly respond with a "68 (or 61) 6B addr" and scan tools programmed to reject all messages that do not conform to "48 (or 41) 6B addr" may be unable to talk to one or more of the controllers on that vehicle.	?	?	Scan Tool Manufacturers should not program their tools to reject all messages that do not conform to "48 (or 41) 6B addr"
3	4/13/09	KWP 2000. The specification defined by ISO 14230-4 known as Keyword Protocol 2000 allows for two different initialization requests. One is a slow baud rate that is identical to the ISO 9141 wake-up process while one is a fast initialization that allows the use of a higher baud rate. Some scan tool manufacturers have reported great difficulty in using both initialization processes successfully. Some KWP 2000 vehicles appear to wake-up with only one or the other initialization process, not either as required by the specification. Other vehicles seem to have initialization problems depending on which one of the slow initialization or fast initialization method was tried first. Once subjected to the slow or fast initialization, some vehicles will refuse to respond to the other method.	KWP 2000	?	Scan tool manufacturers need to spend sufficient time in validating their approach on multiple KWP 2000 equipped vehicles.  Use of the OBD Flow Chart is recommended Note: this needs a better explanation
4	4/13/09	Mode $01 PID $00 Request. In general, the communication process is begun when the scan tool cycles through each of the OBD II protocols (J1850 PWM, J1850 VPW, ISO 9141, ISO 1423-4) one at a time and sends out a J1979 Mode $01 PID $00 (or equivalent) initialization request. All emission-related controllers are supposed to respond and identify the supported PIDs for each controller. On some vehicles, non-emission related controllers may incorrectly respond to this initialization request. In general, however, the non-emission related controller will "wake-up" to a request for only emission-related controllers to "wake-up" but then will correctly identify that it does not support any emission-related PIDs. In some instances, a non-emission related controller will even "wake-up" on a different protocol (e.g., KWP 2000) than the protocol utilized by the emission-related controllers for OBD II requirements (e.g., ISO 9141).	All	?	Upon determining that no PIDs are supported by the controller that has mistakenly responded, a scan tool may need to re-initialize and cycle through the other OBD II protocols before correctly establishing communication with the emission-related controllers on a different protocol.
5	4/13/09	Response time. J1979 indicates that all J1850 protocol controllers are required to respond within 100 ms of a scan tool J1979 request message. However, scan tool manufacturers have often encountered vehicles which do not strictly adhere to this specification. On some vehicles that have multiple controllers, not all controllers will respond within the 100ms window. Some vehicles are designed such that as soon as one controller responds, the 100ms time window is reset again so that the second controller may take up to 100ms after the first controller has responded before responding. Multiple other message timing problems likely exist.	J1850	?	Note:  No solution was offered by CARB in original document
6	4/13/09	Incorrect PID support designation. Often times vehicles will report (via a Mode $01 PID $00 request) PIDs as supported that are actually not supported by the vehicle. Thus, when the specific PID is requested, the vehicle will not respond. In other cases, the vehicle will indeed support PIDs that are not reported as supported in the Mode $01 PID $00 response.	All	?	Scan tool manufacturers need to be aware that these issues exist and may develop creative ways to deal with the problem. Note:  The above recommendation is not a solution
7	4/13/09	Multiple controllers. Many manufacturers have multiple controllers which support some or all OBD II features. Several of these controllers may properly respond to initialization requests, etc. There is no prescribed order, however, in which the controllers must respond to J1979 request messages from the scan tool.	All	?	Scan tools should not try to infer or assume certain priorities in the received messages based solely on the order in which the different controllers responded (e.g., assuming the first controller to respond to a Mode $01 PID $01 request is an engine controller and the second controller to respond is a transmission controller).