MODEL IDENTIFICATION
Note. The following figures are courtesy of General Motors Corp.
| Model | (1) Series Designation |
|---|---|
| 2WD | "C" |
| 4WD | "K" |
| (1) Series codes are determined by fifth character of VIN code. | |
| (1) | Series codes are determined by fifth character of VIN code. |
SERIES CODE DESIGNATIONS (LIGHT TRUCKS & VANS)
DESCRIPTION & OPERATION
Note. The "C" and "K" Series trucks use an Engine Control Module (ECM), Powertrain Control Module (PCM) or Vehicle Control Module (VCM) to maintain engine idle speed during A/C compressor clutch operation.
On vehicles with a Powertrain Control Module (PCM) controlled A/C compressor clutch, the A/C compressor clutch relay is controlled by the PCM. The PCM improves idle quality by delaying A/C compressor clutch engagement until idle speed is increased, and disengages A/C compressor clutch when idle speed is too low. A/C compressor clutch is cycled by PCM. PCM smooths cycling of A/C compressor clutch by adding fuel the instant A/C compressor clutch is applied.
On vehicles without a PCM-controlled A/C compressor clutch, turning on A/C system supplies battery voltage to the A/C compressor clutch and A/C request signal terminal of Engine Control Module (ECM), Powertrain Control Module (PCM) or Vehicle Control Module (VCM). When the ECM, PCM or VCM sees battery voltage at A/C request signal terminal, it maintains idle speed. The ECM, PCM or VCM does not control A/C compressor clutch operation. An A/C pressure cycling switch is used to control A/C compressor clutch operation.