I’ve been grinding away at the engine bay wiring, I’ll save that story for its own post when it’s done. In the meantime I found some interesting (to me, at least) information.
For a while now I’ve been trying to find a CAN database for GM cars – many sources seem to have it (Racelogic, to name one), but no company seems to want to share it in a non-proprietary format. It’s almost like they’re making money by it not being public knowledge. There are free databases online (like the GMLAN Bible and this one) but they’re all incomplete at best. I’d all but given up hope when I stumbled across this thread that mentioned a GM worldwide engineering standard (GMW8762) that defined all the messages on the bus.
You may be asking yourself why I care so much about a CAN database. For the uninitiated, a CAN database file converts the zeroes and ones on the CAN bus into useful information. In this case the ECM transmits pretty much any drivetrain parameter you’d want to know but without a decoder ring it’s all just nonsense. I wanted to read all the broadcast information so I could build a device to display and log these parameters. Frankly none of this is really necessary but I like to tinker. Plus it would be neat to be able to monitor this stuff real-time.
Several sources talk about GMW8762 but I couldn’t find a free PDF online. I bought it from a definitely legitimate and not at all sketchy website for a seemingly arbitrary $29.04. Seeing as how this website is almost certainly not affiliated with any of the standards organizations, I don’t feel bad about attaching a copy of the spec to this post. For the other two people on the internet who wanted this spec, enjoy! I transcribed all the ECM-related messages into a CAN database file which I’ve also attached (it’s a .dbc file, just change the extension to .dbc).
There are a few things I can do with this information:
- Repurpose some of the unused analog inputs (AC pressure sensor, clutch position sensor, fuel level, fuel) which are broadcast on the bus for other sensors. I’m planning on using the AC pressure sensor to add an actual oil temp sensor, I’ll cover this in another post
- Log and display all the data (up to and maybe including making my own digital dash, depending on how ambitious I feel)
- Create a CAN to analog device using a $25 development board. It’ll be a little more work than just buying the development board, but it’ll allow converting any signal on the bus to an analog signal. Useful for driving gauges, etc.
I’ve also been kicking around the idea of making an analog-to-CAN board to monitor other sensors, but I haven’t come up with a good use for that yet. You can buy them for a reasonable price (~$200) as well, so I’m sort of reinventing the wheel here. There will certainly be more CAN-related content coming so stay tuned!
Copy and paste into a text file and change the extension to .dbc:
VERSION “”
NS_ :
NS_DESC_
CM_
BA_DEF_
BA_
VAL_
CAT_DEF_
CAT_
FILTER
BA_DEF_DEF_
EV_DATA_
ENVVAR_DATA_
SGTYPE_
SGTYPE_VAL_
BA_DEF_SGTYPE_
BA_SGTYPE_
SIG_TYPE_REF_
VAL_TABLE_
SIG_GROUP_
SIG_VALTYPE_
SIGTYPE_VALTYPE_
BO_TX_BU_
BA_DEF_REL_
BA_REL_
BA_DEF_DEF_REL_
BU_SG_REL_
BU_EV_REL_
BU_BO_REL_
SG_MUL_VAL_
BS_:
BU_:
BO_ 201 engine_general_status_1: 8 ECM
SG_ engine_run_active : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ powertrain_crank_active : 6|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ powertrain_crank_aborted : 5|1@0+ (0,0) [0|0] “” Vector__XXX
SG_ powertrain_run_aborted : 4|1@0+ (0,0) [0|0] “” Vector__XXX
SG_ PTO_powertrain_run_aborted : 3|1@0+ (0,0) [0|0] “” Vector__XXX
SG_ engine_idle_active : 2|1@0+ (0,0) [0|0] “” Vector__XXX
SG_ engine_speed_status : 1|2@0+ (0,0) [0|0] “” Vector__XXX
SG_ engine_speed : 15|16@0+ (0.25,0) [0|16383.8] “rpm” Vector__XXX
SG_ accelerator_actual_pos_valid : 31|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ cruise_control_active : 30|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ cruise_control_enabled : 29|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ driver_throttle_override_detect : 28|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ driver_throttle_override_ARC : 27|2@0+ (1,0) [0|3] “” Vector__XXX
SG_ driver_thrtl_ovride_dtct_protct : 25|2@0+ (1,0) [0|3] “” Vector__XXX
SG_ accelerator_actual_position : 39|8@0+ (0.3922,0) [0|100] “percent” Vector__XXX
SG_ platform_eng_spd_cmd_superceeded : 45|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ platform_eng_spd_cmd_inhbt_req : 44|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ eng_cylinder_deactivation_mode : 43|2@0+ (1,0) [0|3] “” Vector__XXX
SG_ pwt_brake_pdl_dscrt_in_stat_vld : 41|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ pwt_brake_pdl_dscrt_in_stat : 40|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ remote_vehicle_start_eng_running : 55|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ eng_cyl_deact_event_pending : 54|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ eng_intke_air_boost_press_valid : 51|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ eng_intake_air_boost_press : 63|8@0+ (1,-127) [-127|128] “kPa gage” Vector__XXX
BO_ 249 transmission_general_status_1: 8 ECM
SG_ trans_overall_est_tq_ratio_valid : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ trans_overall_est_tq_ratio : 6|15@0+ (0.0039,0) [0|64] “ratio” Vector__XXX
SG_ trans_out_shaft_ang_vel_valid : 23|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ trans_out_shaft_ang_vel_sns_pres : 22|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ trans_out_rot_roll_cnt_reset : 21|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ trans_out_rot_roll_ct_valid : 20|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ reserved_0f9_1 : 19|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ reserved_0f9_2 : 18|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ reserved_0f9_3 : 17|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ reserved_0f9_4 : 16|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ trans_out_shaft_ang_vel : 31|16@0+ (0.25,0) [0|16384] “rpm” Vector__XXX
SG_ trans_out_rotations_roll_ct : 47|16@0+ (1,0) [0|99999] “none” Vector__XXX
SG_ trans_cruisectrl_spd_shft_evnt : 63|8@0+ (1,0) [0|99999] “none” Vector__XXX
BO_ 493 fuel_system_request: 8 ECM
SG_ fuel_ctrl_system_fault_present : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ fuel_pmp_en_discrete_output : 6|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ fuel_pressure_requested : 1|10@0+ (1,0) [0|1023] “kpa” Vector__XXX
SG_ instantaneous_fuel_flow_est : 23|16@0+ (0.0009765625,0) [0|63.9990234375] “g/s” Vector__XXX
SG_ advanced_fuel_flow_estimated : 39|16@0+ (0.0009765625,0) [0|63.9990234375] “g/s” Vector__XXX
SG_ commanded_air_fuel_ratio : 55|16@0+ (0.00048828125,0) [0|31.99951171875] “afr” Vector__XXX
BO_ 495 fuel_system_request_2: 8 ECM
SG_ mass_air_flow_valid : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ mass_air_flow : 23|16@0+ (0.01,0) [0|655.35] “g/s” Vector__XXX
BO_ 501 trans_general_status_2: 8 ECM
SG_ tras_estimated_gear : 3|4@0+ (1,0) [0|16] “gear_number” Vector__XXX
BO_ 707 engine_torque_status_3: 8 ECM
SG_ engine_manifold_abs_pres_valid : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_manifold_abs_pres : 55|8@0+ (0.5,0) [0|127.5] “kPa” Vector__XXX
BO_ 977 engine_general_status_2: 8 ECM
SG_ throttle_pos_valid : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ throttle_progression_status : 6|2@0+ (1,0) [0|3] “” Vector__XXX
SG_ throttle_pos : 15|8@0+ (0.392156862745098,0) [0|100] “percent” Vector__XXX
SG_ engine_coast_fuel_cutoff_active : 22|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ eng_oil_starvation_indication_on : 21|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ instant_fuel_consumption_rate : 35|12@0+ (0.025,0) [0|102.375] “liter/hr” Vector__XXX
BO_ 1001 vehicle_speed_and_distance: 8 ECM
SG_ vehicle_speed_avg_driven_valid : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ vehicle_speed_avg_driven : 6|15@0+ (0.015625,0) [0|511.984375] “kph” Vector__XXX
SG_ vehicle_speed_average_driven_src : 23|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ dist_roll_cnt_avg_driven_valid : 22|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ dist_roll_cnt_avg_drvn_rest_occr : 21|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ dist_roll_cnt_avg_driven : 20|13@0+ (0.125,0) [0|1023.875] “m” Vector__XXX
SG_ dist_speed_avg_non_driven_valid : 39|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ vehicle_speed_avg_non_driven : 38|15@0+ (0.015625,0) [0|511.984375] “kph” Vector__XXX
SG_ dist_roll_cnt_avg_driven_src : 55|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ dist_roll_cnt_avg_nondriven_vld : 54|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ dist_roll_cnt_avg_nondirven_rst : 53|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ dist_roll_cnt_avg_non_drive : 52|13@0+ (0.125,0) [0|1023.875] “m” Vector__XXX
BO_ 1019 engine_fuel_status: 2 ECM
SG_ fuel_alcohol_coposition_valid : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ emissions_related_fuel_lvl_low : 6|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ fuel_lvl_emissions_reltd_valid : 5|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ fuel_alcohol_comp_adapt_in_prog : 4|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_fuel_control_state : 1|2@0+ (1,0) [0|3] “” Vector__XXX
SG_ fuel_alcohol_compositon : 15|8@0+ (0.392156862745098,0) [0|100] “percent” Vector__XXX
BO_ 1217 engine_general_status_4: 8 ECM
SG_ barometric_pressure_valid : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_coolant_temperature_valid : 6|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ inlet_temperature_validity : 5|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ ambient_temperature_pwrtrn_mask : 4|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ ambient_temperature_pwrtrn_valid : 3|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_cond_met : 2|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_cond_fault_present : 1|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_warmup_cycle_achieved : 0|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ barometric_pressure_abs : 15|8@0+ (0.5,0) [0|127.5] “kpa” Vector__XXX
SG_ engine_coolant_temp : 23|8@0+ (1,-40) [-40|215] “C” Vector__XXX
SG_ engine_intake_air_temp : 31|8@0+ (1,-40) [-40|215] “C” Vector__XXX
SG_ ambient_air_temp : 39|8@0+ (0.5,-40) [-40|87.5] “C” Vector__XXX
SG_ cold_start_cond_met : 47|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ cold_start_cond_fault_present : 46|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_oil_hot_indicator : 45|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ def_remaining_distance : 49|10@0+ (100,0) [0|102300] “km” Vector__XXX
SG_ engine_economy_mode_commanded : 54|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ def_remaining_distance_validity : 50|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ def_warning_rem_dist_valid : 53|3@0+ (1,0) [0|7] “” Vector__XXX
BO_ 1225 transmission_general_status_3: 5 ECM
SG_ trans_oil_temp_valid : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ trans_oil_temp_sensor_present : 6|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ trans_thermal_mgmt_status : 1|2@0+ (1,0) [0|3] “” Vector__XXX
SG_ trans_oil_temp : 15|8@0+ (1,-40) [-40|215] “degC” Vector__XXX
BO_ 1233 engine_general_status_5: 8 ECM
SG_ engine_oil_temperature_valid : 7|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_oil_pres_valid : 6|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_oil_pres_low_indicator_on : 5|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_oil_lvl_low_indicator_on : 4|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_oil_change_indicator_on : 3|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_hot_fuel_enrichm_ind_on : 2|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_hot_stop_engine_ind_on : 1|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ air_conditioning_off_ind_on : 0|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_oil_temperature : 15|8@0+ (1,-40) [-40|215] “C” Vector__XXX
SG_ engine_oil_pressure : 23|8@0+ (4,0) [0|1020] “kpa” Vector__XXX
SG_ reduced_power_indicator : 31|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ starting_disabled_indicator : 30|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ check_fuel_cap_indicator : 29|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ fuel_level_percent_valid : 28|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ fuel_total_capacity : 27|12@0+ (0.125,0) [0|511.875] “l” Vector__XXX
SG_ fuel_level_percent : 47|8@0+ (0.392156862745098,0) [0|100] “%” Vector__XXX
SG_ engine_shutdown_pending_ind_on : 49|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_shutdown_active : 48|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diesel_glow_plug_ind_on : 55|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_water_in_fuel_ind_on : 54|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ exhaust_particulate_fltr_warn_on : 53|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ high_electrical_load_requested : 52|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ change_fuel_filter_ind_on : 51|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ check_engine_ind_on : 50|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ engine_max_speed_limit : 63|8@0+ (32,0) [0|8160] “rpm” Vector__XXX
BO_ 1906 diag_trouble_code_info_extended: 8 ECM
SG_ diag_trouble_code_triggered : 0|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_trouble_code_source : 15|8@0+ (1,0) [0|255] “” Vector__XXX
SG_ diag_trouble_code_number : 23|16@0+ (1,0) [0|65535] “” Vector__XXX
SG_ diag_trouble_code_fail_type : 39|8@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_warn_ind_reqested_stat : 47|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_tst_fail_since_pwrup_stat : 46|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_tst_nopass_since_pwrup_stat : 45|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_history_status : 44|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_tst_failed_since_code_clrd : 43|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_tst_nt_pass_since_code_clrd : 42|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_current_status : 41|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_code_supported : 40|1@0+ (1,0) [0|1] “” Vector__XXX
SG_ diag_trouble_code_fault_type : 55|8@0+ (1,0) [0|1] “” Vector__XXX
VAL_ 201 engine_speed_status 3 “Invalid” 1 “Degraded Operation” 0 “Normal_Operation” ; VAL 201 platform_eng_spd_cmd_superceeded 1 “Inhibit Platform Engine Speed Control” 0 “Allow Platform Engine Speed Control” ;
VAL_ 201 eng_cylinder_deactivation_mode 3 “Reactivation In Progress” 2 “Half Of Total Cylinders Active” 1 “Deactivation In Progress” 0 “All Cylinders Active” ;
VAL_ 1001 vehicle_speed_average_driven_src 1 “Wheel Speed” 0 “Transmission Output Speed” ;
VAL_ 1001 dist_roll_cnt_avg_driven_src 1 “Wheel Speed” 0 “Transmission Output Speed” ;
VAL_ 977 throttle_progression_status 0 “Map A” 1 “Map B” 2 “Map C” 3 “ECM Selected Progression”;
VAL_ 1019 engine_fuel_control_state 2 “Stoichiometric Closed Loop” 1 “Non-Stoichiometric Closed Loop” 0 “Open Loop” ;
VAL_ 1225 trans_thermal_mgmt_status 2 “Driver Intervention Required” 1 “Counter-measures Active” 0 “Normal” ;
VAL_ 1233 trans_thermal_mgmt_status 3 “Type C” 2 “Type B” 1 “Type A” 0 “Not Supported” ;
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