A/C - Clutch Control & Cooling Fan Diagnostic Update

90pontiac18
Bulletin Number: 90-6-39
Reference Number: 016526
Publish Date: 9/90
Subject: SERVICE MANUAL UPDATE - SEC. 6E3 (CONVENIENCE CENTER ID, DIAGNOSTIC GUIDELINES)
Models
Affected: 1990 GRAND PRIX MODELS

A/C CLUTCH CONTROL AND COOLING FAN CONTROL SUPPLEMENTAL DIAGNOSTIC GUIDELINES.

FIGURE 1:

FIGURE 2:

Some late production 1990 Grand Prix models may be equipped with a new style convenience center that utilizes embossed terminal cavity numbers adjacent to each terminal cavity of the relay center (see Figure 1).

The old style unit does not utilize embossed numbers at the terminal cavities (see Figure 2). However, numbers were already assigned to the cavities in the diagnostic charts of the service manuals. The numbers were changed for the "new style" convenience center to comply with certain standards.

The circuits contained within the "new style" convenience center are in the same physical locations as those of the "old style" unit.

Diagnostic charts used in DRIVEABILITY AND EMISSIONS (SECTION 6E3) and ELECTRICAL DIAGNOSIS (SECTION 8A) may require probing or jumpering of the numbered terminal cavities as part of the diagnostic process. This is particularly true in diagnosis of the A/C clutch control and cooling fan control circuits.

If the vehicle is equipped with the "new style" convenience center (Figure 1), use the attached supplemental diagnostics that apply to the vehicle. If the vehicle is equipped with the "old style" convenience center (Figure 2), use the applicable Service Manual diagnostics.
The supplemental Service Manual pages are listed below:

YEAR CARLINE ENGINE VIN PAGES