Decoding OBDII trouble codes

[retepsnikrep]

OBDII readers are not created equal, there are lots of manufacturer specific codes that can only be obtained at vast expense or reverse engineering.

[Demon]

Can I chose another answer?

That's what I was afraid of. That the Snap-On and other professional tools have a catalogue of codes that is not accessible to the public.

Cause right now that OBD-II codereader is not very useful. It tells me that me catalyser is finished, no surprise on a 2002 Buick Rendezvous with over 200K km. It wouldn't even report a generic code for the ABS while the light came on in the dash.

That's where the Snap-On tool shined, it had info on each individual wheel sensor.

[Demon]

You are right when it comes to manufacturer specific codes. Just looking at ScanXL, there's different software add-ons by manufacturer. I have a Buick Rendezvous and it's staggerring how many more codes I can get to and the ABS ones that interested me are here (ScanXL links to Palmer for their references):

http://www.palmerperformance.com/sup...m_enhanced.php

Engine Parameters, 2100 parameters
Transmission Parameters, 491 parameters
Fuel Pump Parameters, 15 parameters
ABS Parameters, 304 parameters
Airbag Parameters, 69 parameters
Hybrid Battery Parameters, 56 parameters
Hybrid Powertrain Parameters, 186 parameters

And this is the subset that I probably have in my OBD-II reader:

Generic OBD-II Parameters, 229 parameters

I cannot see myself trying to reverse-engineer formulas for each individual sensor, the task is staggerring. The only good thing is that I have a Buick and my wife has a Pontiac, so the codes would work for both cars.

Robert

[retepsnikrep]

Thanks for the ideas so far.

Here is some more data for a few functions.

'MPI_MDL Temp C
'$9C $97 = 21C
'$88 $77 = 29C
'$83 $80 = 31C
'$6B $76 = 40C
'$67 $73 = 42C

'DC-DC Converter Temp C
'$97 $22 = 22C
'$7F $41 = 33C
'$77 $41 = 36C
'$76 $6F = 37C
'$72 $6F = 39C

'BAT_MDL Volts
'$91 $10 = 152V
'$95 $00 = 155V
'$98 $0C = 158V
'$9A $05 = 160V
'$9C $00 = 162V
'$9D $00 = 163V
'$9E $00 = 164V

'MPI_MDL Volts
'$97 $7F = 157V
'$98 $B2 = 158V
'$9B $99 = 162V
'$9C $80 = 163V

'MPI_MDL Amps
'$7F $9E = 2A
'$7C $9C = 8A
'$78 $9B = 16A
'$83 $9F = -6A
'$83 $9A = -6 to -8A

TORQUE NM
'$2D $5A = 0 NM
'$3A $5A = 8.4NM
'$41 $5A = 28 to 30 NM
'$2A $5A = -8.4 NM
'$29 $5A = -11.2 NM

Any further ideas?

[retepsnikrep]

Thanks for those ideas.

Some more resarch has revealed this data is all a single byte so I have deleted the second red herring byte that should make it a lot easier.

'MPI_MDL Temp C
'$9C = 21C
'$88 = 29C
'$83 = 31C
'$6B = 40C
'$67 = 42C

'DC-DC Converter Temp C
'$97 = 22C
'$7F = 33C
'$77 = 36C
'$76 = 37C
'$72 = 39C

'BAT_MDL Volts
'$91 = 152V
'$95 = 155V
'$98 = 158V
'$9A = 160V
'$9C = 162V
'$9D = 163V
'$9E = 164V

'MPI_MDL Volts
'$97 = 157V
'$98 = 158V
'$9B = 162V
'$9C = 163V

'MPI_MDL Amps
'$7F = 2A
'$7C = 8A
'$78 = 16A
'$83 = -6A

TORQUE NM
'$2D = 0 NM
'$3A = 8.4NM
'$41 = 28 to 30 NM
'$2A = -8.4 NM
'$29 = -11.2 NM

Any further ideas?