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Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
You got into a situation where the basic system changed from mechanical to electronic signaling.
The signal feeds speed info to the computer to calculate shift point based on the throttle position sensor throttle angle..
The signal is also used for OD control.
This signal also is used for the speedometer drive.
Not shifting is the calculation cannot be made because speed sensing in absent.
There should be a transmission code set due to this.
Lots of people who do a swap from a late model back to early get into this problem because they don't check the differences first.
To get around this, the trans usually has to be modified., and the harness plugs are different.
The harness plugs being different is a very good clue not to use that trans in place of the original if they are not the same. that's the reason they are different.
The pin outs to the leads may be different as well as the sensors used..
Swapping sensors usually is not the answer either because of the way they pick up the rotation signal..
.
The signal feeds speed info to the computer to calculate shift point based on the throttle position sensor throttle angle..
The signal is also used for OD control.
This signal also is used for the speedometer drive.
Not shifting is the calculation cannot be made because speed sensing in absent.
There should be a transmission code set due to this.
Lots of people who do a swap from a late model back to early get into this problem because they don't check the differences first.
To get around this, the trans usually has to be modified., and the harness plugs are different.
The harness plugs being different is a very good clue not to use that trans in place of the original if they are not the same. that's the reason they are different.
The pin outs to the leads may be different as well as the sensors used..
Swapping sensors usually is not the answer either because of the way they pick up the rotation signal..
.
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