QuestionQUESTION: My daughters Accent suddenly wouldn't shift out of 1st gear, it was about a quart low on trans fluid, that didn't change anything. No reverse 2nd or 3rd or od. Its a 1.6 engine. I have to travel a ways to try and fix this so any help is appreciated, I have an obd II scanner but it looks as if the tcm may use something else??
Can you tell me where the tcm is located on this car? I am more familiar with American cars so I would look to the VSS first in in case like this.
Thanks
ANSWER: One quart is not typically enough to notice any change in shifting.
Before heading out, have your daughter check to see if there's a harsh engagement into reverse. Both this symptom and the one you describe are consistent with a faulty pulse generator A (input speed sensor). In this case, you may want to purchase the pulse generators-- both the input and output come together with a short harness-- and take with you to replace.
Whether your OBD scanner communicates with the TCM apparently depends on the scanner. I have very little experience with anything other than the factory scan tool, but I've heard mixed reports from people who've gone places like Auto Zone. Some will be able to report trans codes while others will not.
The TCM itself is behind the left side of the dash.
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QUESTION: Hi,
As per previous question, I did scan and came up with codes po732,733 and 734.........can you tell me the most likely cause for this? Havent changed the pulse generator yet. I know these relate to incorrect gear ratio.
Thanks
ANSWER: The most frequent causes of these trouble codes are internal transmission problems-- they basically indicate the transmission is slipping.
But I don't think we should jump to this conclusion just yet. A faulty pulse generator signal can cause the TCM to think the transmission is slipping when it is not. Typically, this will result in a pulse generator error code as well (P0717 or P0722), but this doesn't always occur.
Is the transmission stuck in 1st gear, or is it actually in failsafe (3rd gear only)?
Does it have a harsh engagement into reverse?
Do you have the capability of reading TCM sensor data with your scanner? If so, monitor the pulse generator signals. You should have a reading from pulse generator A (input speed sensor) approximately equal to engine speed when the car is idling in neutral, and zero when idling in gear. Pulse generator B (output speed sensor) should be proportional to vehicle speed.
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QUESTION: Hi,
The trans is stuck in 1st gear, not the failsafe. Drive, low and 2 all seem to be in 1st gear, nothing in reverse. It doesnt seem to be harsh at all going into reverse, and I have made this observation, the tach does seem to drop a little like when putting a functioning trans into reverse.
Kinda says to me the electronics are working, but something inside isnt fully engaging. I havent been able to locate a better scanner to check the pulse generator yet.
Thanks......
AnswerIf you have no reverse, that pretty much eliminates the pulse generators as a potential cause.
Check to be sure you're getting the correct reading from the range switch regarding gear position. Otherwise, the problem is internal in the transmission.
