Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1990 Geo Metro L3-61 1.0LFACTORY OEM SERVICE PROCEDURE
Engine Control Module: Service and Repair
NOTE: To prevent possible Electrostatic Discharge damage: DO NOT touch the ECM connector pins or soldered components on the ECM circuit board. Service of the ECM consists of complete replacement for the ECM. There are no serviceable parts, such as a PROM or Mem-Cal to replace inside this ECM. If the ECM is determined to be faulty, it is then to be replaced as a complete assembly.
IMPORTANT: When replacing the production ECM with a service ECM, it is important to transfer the broadcast code and production ECM number to the service ECM label. This will allow positive identification of the ECM parts throughout the service life of the vehicle.
REMOVE OR DISCONNECT:
1. Negative battery cable.
2. Passenger compartment fuse block.
3. 3 fasteners from ECM bracket.
4. ECM connectors (2).
5. ECM from passenger compartment.
INSTALL OR RECONNECT:
1. Connectors (2) to new ECM.
2. ECM into underdash location.
3. 3 fasteners to ECM bracket.
4. Tighten securely.
5. Fuse block to mounting bracket.
6. Negative battery cable.
IMPORTANT: When replacing the production ECM with a service ECM, it is important to transfer the broadcast code and production ECM number to the service ECM label. This will allow positive identification of the ECM parts throughout the service life of the vehicle.
REMOVE OR DISCONNECT:
1. Negative battery cable.
2. Passenger compartment fuse block.
3. 3 fasteners from ECM bracket.
4. ECM connectors (2).
5. ECM from passenger compartment.
INSTALL OR RECONNECT:
1. Connectors (2) to new ECM.
2. ECM into underdash location.
3. 3 fasteners to ECM bracket.
4. Tighten securely.
5. Fuse block to mounting bracket.
6. Negative battery cable.
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.