Engine Control Module: Testing and Inspection
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More supporting gear
Torque wrench
Use the factory procedure with the right tightening tool.
Manual-based work becomes much easier when you can torque correctly.
Shop on Amazon →Trim tool set
Useful for clips, covers, and trim pieces called out by the manual.
Most manual procedures assume you have a good trim removal kit.
Shop on Amazon →Multimeter kit
Great for electrical troubleshooting and manual-tested circuits.
Electrical work in manuals often needs a meter more than another wrench.
Shop on Amazon →^ Failure to start or vehicle is stalling.
^ The "CHECK ENGINE" "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR" light will flash or light up, but no trouble codes will be present.
^ Vehicle instrument panel displays may be inoperative.
^ The control module may or may not communicate with the scanner.
^ Other intermittent driveability problems.
Incorrect PROM or MEMCAL removal and replacement can create solder joint problems or aggravate an existing condition. See PROM or MEMCAL INSTALLATION for proper procedures.
If a solder joint problem results in a "hard" failure, normal test procedures will usually pinpoint a faulty control module. Many symptoms caused by poor solder joints in the control module result in intermittent problems, but they may be hard to duplicate during troubleshooting. Control module's with solder joint problems are sensitive to heat and vibration. You can check for these internal control module problems in either, or both, of the following ways:
^ Remove the control module from its mounting bracket and extend it on the harness so that you can expose it to the vehicle heater ducts. Alternatively, use flexible ducting to route air from the heater to the control module location. Then run the engine and operate the heater at the "MAX HEAT" position. This exposes the control module to approximately 140°F.
^ With the engine running, tap on the control module several times with your hand or finger tips to simulate vehicle vibration.
If the engine stumbles or stalls, the "CHECK ENGINE" "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR" light flashes, or any of the previous symptoms occur, the control module may have bad solder joints on the circuit board.