Overcoming the Fear - TCC Data PID Diagnostics Is Not as Scary as It Seems. - Motor Age - Automotive training, certification & parts info

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Overcoming the FearTCC Data PID Diagnostics Is Not as Scary as It Seems.

Publish date: Jun 1, 2008
By: Travis Dewitz
Source: Motor Age

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The PIDs Have Spoken

Figure 4 Here you can see the obvious rpm change when the torque converter is applied and disengaged.

Now you can make your next move. If there is no indication of excessive TCC slip, you may need to get more information from the customer or look at freeze frame data. The problem may be intermittent or related to temperature, debris, fluid or vehicle load.

Figure 5 In the top image, you can see that there was no pintle bump, which indicates that the pintle in the solenoid did not move. The bottom image shows the normal (correct) operation of the TCC solenoid.

If you verified that there is excessive TCC slip or no TCC operation, make sure the TCC lock-up solenoid and circuit are working correctly. If your scan tool has TCC bi-directional control capabilities, try to operate the solenoid and listen for an audible click. If there is a click, your problem most likely is an internal issue we will get to shortly. Sometimes you may not be able to hear a click from a good solenoid because of the style of solenoid or its location in the transmission. If you do not hear an audible click, you may need to use a low amp probe and scope to see the actual TCC solenoid amperage and pintle bump (as in Figure 5).

If your scan tool does not have TCC control capability, then you will need to see how that solenoid is operated. Is it ground-side or power-side controlled? What color wire operates the solenoid, and where is a good test point? Once you have this information, you can operate the solenoid yourself by either supplying power or a ground to the control side of the TCC solenoid.

If you don't hear an audible click, you will need to test the TCC circuit from your test point to the lock-up solenoid. If you do hear an audible click, verify the circuit from your test point to the Powertrain Control Module (PCM) or Transmission Control Module (TCM). One way to test this is by probing the control-side circuit and making sure the PCM is commanding lock-up while on a test drive. If you are not getting a command signal, you will have to verify the circuit and PCM. Also, be aware of the PCM inputs like brake switch, transmission fluid temperature sensor, etc., that have an intended effect on TCC operation. If you do get a PCM command, you now know the problem is probably internal. We will go over that soon.

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Travis Dewitz

Articles by Travis Dewitz

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Travis Dewitz