Bench Testing the 6L50-6L80-6L90-6T70-6T75 TEHCM
automated so once the vehicle is in park and you’ve selected the feature on the scan tool, it’ll cycle all of the solenoids, flushing debris from the solenoids and their circuits. If the performance DTC resets or
the bench test fails, you’ll need to replace the TEHCM. If the problems appear to be gone after the cleaning, you can reuse the TEHCM.
TEHCM Speed Sensor Testing You can test the speed sensors in
these transmissions and transaxles by supplying a substitute signal to isolate whether the problem is in the sensor or the TEHCM. The sensors feed their sig- nals directly into the TEHCM. A signal generator can simulate the signal from the sensors. • Connect your signal generator to the speed sensor wiring connec- tor on the TEHCM.
• With your scan tool connected to the vehicle, monitor the ISS and OSS signals on the scan tool.
The signal generator creates an
8-volt square wave and can vary the frequency of the signal. As you change the frequency, the speed indicated on the scan tool should change with it. If the scan tool speed sensor signal
changes as you vary the frequency on the signal generator, the TEHCM is working properly, so the problem is probably the speed sensor itself. If the speed signal isn’t present on the scan tool, the problem is likely the TEHCM.
Replacing the TEHCM If your diagnosis has led you to
replace the TEHCM, there are a few things you should keep in mind: • The TEHCM will require pro- gramming to match the vehicle or it won’t operate.
• You’ll need to perform a Fast Learn procedure to establish the baseline shift adapt values or shift problems will occur.
• You’ll need to replace the filter plate; never try to reuse the filter plate.
That’s about it for now, so until
next time, remember: “Our aspirations are our possibilities.”
Figure 4B: PWM solenoid amperage: 1.5-4.0 amps 20 GEARS August 2012 Figure 4A: On/off Solenoid amperage: 0.3-0.7 amps
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