Engine Controls - Precautions Electronic System Testing

Classification:
EC96-013

Reference:
NTB96-104

Date:
November 13, 1996

PRECAUTIONS FOR ELECTRONIC CONCENTRATED ENGINE CONTROL SYSTEM (ECCS) TESTING

APPLIED VEHICLES:
All

SERVICE INFORMATION





Always use caution when performing electrical checks on the electrical harness or engine control module (ECM) to avoid damaging the ECM. NEVER apply direct battery voltage to any terminal of the ECM by either connecting a 12 volt battery positive (+) terminal, or by jumping (short circuiting) any actuator that is connected to the ECM. Below is a partial list of typical actuators:

^ Relays (fuel pump, A/C, cooling fan, EFI)

^ Solenoid valves (EGR control, purge control, vent control, vacuum cut valve bypass or intake valve timing control)

^ Fuel injectors

^ IACV-AAC valve or IACV-FICD valve.

NOTE:
Applying battery voltage to the ECM without sufficient resistive load (normally supplied by an actuator) will cause an over-current condition to the ECM transistor resulting in instant, permanent damage to the ECM.