1997-2003 Grand Prix Climate Control Diagnostics
This is a quick reference for how to use the diagnostic mode built into the C2J, the dual zone digital climate control system which came installed in some 1997 through 2003 Pontiac Grand Prix Models.
When I still had my 1999 Grand Prix, any time I wanted to look this up I always had trouble remembering the terms I need to search for to retrieve it, so I stole mirrored this from This Forum Post and tried to clean it up a little.
Enter diagnostics mode:
Press and hold both the Driver and Passenger knobs in simultaneously until the display changes to read “-00”.
To change position, turn the Driver knob to the desired number and turn the Passenger knob one click to view the data for that position.
To return to normal operation, press the MODE button next to the Passenger temperature knob.
| Position | Description | Observed Values |
|---|---|---|
| -00 | Error Codes | List of Trouble Codes Below |
| -01 | (servo position) | 103-107 |
| -02 | (servo position) | 128 |
| -03 | (servo position) | 150 |
| -04 | CJ2 Fan Speed | Low=15, 29, 44, 58, 71, 86, 110=High, CJ2 Unit will adjust to other increments as needed |
| -05 | (servo position) | 93 88-191 |
| -06 | (servo position) | -152 00-252 |
| -07 | (servo position) | 00 0, 34-255 |
| -08 | (servo position) | -155 00-255 |
| -09 | (servo position) | 00 0, 23-255 |
| -10 | ? | 04 04 |
| -11 | CJ2 Vent Mode | 1=Def, 2=Bilevel, 3=Auto, 4=Lower, 5=Def+Lower |
| -12 | Engine Coolant Temp | -60 degrees 80=104, 95=131, 100=140 Peak@135°F |
| -13 | Actual Vehicle Speed in MPH | 88 |
| -14 | (servo position) | 00 21=0 |
| -15 | ? | 39 44 |
| -16 | Radiator low fan turn on temp | -106 207 |
| -17 | Radiator low fan turn off temp | 196 199 |
| -18 | ? | 50 51 |
| -19 | (servo position) | 162-169 40-172 |
| -20 | Affected by cabin temp sensor | 89 50-172 |
| -21 | (servo position) | 00 |
| -22 | Sunload Sensor | -117 LIGHT=126, 218=DARK |
Trouble Codes
| Trouble Code | Description |
|---|---|
| 00 | No System Fault |
| 01 or 101 | Inside Air Temperature Sensor Short |
| 02 or 102 | Inside Air Temperature Sensor Open |
| 03 or 103 | Ambient Outside Temperature Sensor Short |
| 04 or 104 | Ambient Outside Temperature Sensor Open |
| 05 or 105 | LH Electric Actuator Open or Short |
| 06 or 106 | RH Electric Actuator Open or Short |
| 07 or 107 | UART Serial Data Line Fault |
| 08 or 108 | Solar Sensor Open |
To Clear codes, press the A/C Mode button. A two digit code indicates a current fault A three digit code indicates a historic fault.