6000 V6-173 2.8L (1988)
Engine Control Module: Component Tests and General Diagnostics
Checking Control Module For Bad Solder Joints
Some control modules may have problems due to cracked solder joints on the circuit board. These internal control module problems can cause the
following symptoms:
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Failure to start or vehicle is stalling.
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The "CHECK ENGINE" "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR" light will flash or light up, but no trouble codes
will be present.
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Vehicle instrument panel displays may be inoperative.
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The control module may or may not communicate with the scanner.
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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 modules 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:
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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.
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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.
ECM Diagnosis
READING CODES
To read the codes, use a "Scan" tool, or ground the diagnostic terminal, with the engine not running and the ignition "ON." The "Service Engine
Soon" light will flash Code 12 three times and then flash each code stored in memory three times. All codes stored in memory would have been
read when Code 12 was flashed again. No new codes can be stored when in the diagnostics mode (diagnostics lead grounded). This eliminates
confusion while the system is being worked on.
Electronic Control Module (ECM)
A faulty Electronic Control Module (ECM) will be determined in the diagnostic charts or by a Code 55.
MEM-CAL
An incorrect or faulty Mem-Cal, which is part of the ECM, may set a Code 41 or 51.
CLEARING CODES
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Ignition "OFF."
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Disconnect ECM fuse in holder for 30 seconds.
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Since the ECM can have a failure which may affect only one circuit, following the diagnostic procedures in this section will determine which
circuit has a problem and where it is.
If a diagnostic chart indicates that the ECM connections or ECM is the cause of a problem, and the ECM is replaced, but does not correct the
problem, one of the following may be the reason:
Problem with the ECM terminal connections.
The diagnostic chart will say ECM connections or ECM. The terminals may have to be removed from the connector in order to check them
properly.
ECM, or Mem-Cal is not correct for the application.
The incorrect components may cause a malfunction and may or may not set a code.
Problem is intermittent.
This means that the problem is not present at the time the system is being checked. In this case, refer to the "Symptoms" portion of the manual
and make a careful physical inspection of all portions of the system involved.
Shorted solenoid, relay coil, or harness.
Solenoids and relays are turned "ON" and "OFF" by the ECM, using internal electronic switches called "drivers." Each driver is part of a
