Vehicles produced between 1980 and 1991 may experience a no start condition due to a dead battery. Follow the service manual procedures to test the battery and charging system. If the battery and charging system are functioning normally, an unusual current draw may have discharged the battery, resulting in the no start. The following procedure has been developed using the parasitic draw test switch, tool J 38758.
Past service procedures do not address solid state failures that appear as intermittent after the battery has been disconnected and reconnected. Utilizing tool J 38758, allows the vehicle to be started, driven, and all electrical system items cycled, without interrupting electrical system continuity. The following procedure supersedes all past "Battery Electrical Drain Test Procedures."
Tools needed: - J 38758 Parasitic Draw Test Switch (Figure 1) - Ammeter with at least 10 amp measurement capabilities
1. Remove battery cable from battery negative terminal.
2. Install the parasitic draw test switch male-end, to negative battery terminal.
3. Turn test switch knob to the "OFF" position.
4. Install negative battery cable to female end of the test switch tool.
5. Turn the test switch tool knob to the "ON" position.
6. Road test vehicle while activating all accessories (radio, A/C, etc.).
7. Turn ignition switch to the "Locked" position and remove ignition key.
8. Set ammeter to the 10 amp scale and connect to terminals on test switch tool.
9. Turn test switch tool knob to the "OFF" position to allow current to flow through the ammeter.
10. Check current reading. If current reading is at or below two amps, turn the test tool knob to the "ON" position (to maintain continuity in the electrical system) and switch down to the two amp scale for a more accurate reading when drain test tool knob is turned "OFF".
11. If current draw is unusually high for the vehicles overall electrical content, remove system fuses one fuse at a time until the current draw returns to an acceptable value. Perform steps 8 through 10 each time a fuse is removed. Refer to the ELECTRICAL DIAGNOSIS section for specific circuit schematics.
12. When cause of excessive current draw has been located and repaired, remove parasitic draw test switch and ammeter and connect negative battery cable to negative battery terminal.
Please include this procedure in your Service Manuals under Section 6D1 - Battery.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.