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Old 04-15-2008, 09:56 PM
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paulmeisterpk paulmeisterpk is offline
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How do I know when my Trans Resistor is Bad?

So my car shifts pretty firmly from gear to gear, but I've been reading about the transmission resistor that seems to go bad, and I'm wondering how to tell if it has failed. So long story short, how do I know if I need to put a new one in (or replace it myself), and what it's purpose is?
Sorry for the Noob question.
Thanks,
Paul
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Old 04-15-2008, 10:10 PM
YourConfused YourConfused is offline
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unplug it and measure resistance across the 2 pins on it. should be something around 12 ohms. I think that Trevor could inform you of its function better than I cause I am too lazy to go into detail.
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Old 04-15-2008, 10:16 PM
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Quote:
Originally Posted by paulmeisterpk View Post
So my car shifts pretty firmly from gear to gear, but I've been reading about the transmission resistor that seems to go bad, and I'm wondering how to tell if it has failed. So long story short, how do I know if I need to put a new one in (or replace it myself), and what it's purpose is?
Sorry for the Noob question.
Thanks,
Paul
Hi Paul. If it is the resistor that is faulty you get hard changes. You should get a code posted.
The resistor is 12 Ohm, you could check the resistance to see.
It is used as a voltage dropping resistor, like the old Ballast resistor that was used on Ignition systems.

Harvey.
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Old 04-15-2008, 10:29 PM
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Quote:
Originally Posted by paulmeisterpk View Post
So my car shifts pretty firmly from gear to gear, but I've been reading about the transmission resistor that seems to go bad, and I'm wondering how to tell if it has failed. So long story short, how do I know if I need to put a new one in (or replace it myself), and what it's purpose is?
Sorry for the Noob question.
Thanks,
Paul
Greetings Paul,

If you can lay your hands on a multi meter you can test the resistance which should measure from 9 - 15 ohms and is usually 12 ohms.

You will get hard shifts only if the resistance is low, or the resistor is a dead short.

The dropping resistor introduces a second series of current pulses applied in parallel with the control signal to solenoid A. These shorter pulses are applied during the off cycles and are timed to check the travel of the armature as it reaches the closed position, thus reducing both shock and noise. These secondary parallel signals in effect, “round off” the closing period and reduce the closing shock.

It will be appreciated that increasing the resistance in the circuit, or opening the circuit by omitting the dropping resistor, has two outcomes. Firstly the relative electrical off time is increased, thus increasing the line pressure and therefore makes shifts more abrupt. Importantly as an undesirable second issue, shock loads applied to the valve are increased.
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Old 04-15-2008, 10:35 PM
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Originally Posted by Trevor View Post
Greetings Paul,

If you can lay your hands on a multi meter you can test the resistance which should measure from 9 - 15 ohms and is usually 12 ohms.

You will get hard shifts only if the resistance is low, or the resistor is a dead short.

The dropping resistor introduces a second series of current pulses applied in parallel with the control signal to solenoid A. These shorter pulses are applied during the off cycles and are timed to check the travel of the armature as it reaches the closed position, thus reducing both shock and noise. These secondary parallel signals in effect, “round off” the closing period and reduce the closing shock.

It will be appreciated that increasing the resistance in the circuit, or opening the circuit by omitting the dropping resistor, has two outcomes. Firstly the relative electrical off time is increased, thus increasing the line pressure and therefore makes shifts more abrupt. Importantly as an undesirable second issue, shock loads applied to the valve are increased.
thanks Trevor for adding your input here as it is exacting and should be of help to Paul.
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Old 04-16-2008, 06:08 PM
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Thank you Trevor. That is actually what I thought it did. I had a controls class and know a bit about electronics. I put in a shift kit when I rebuilt my transmission last year, so I wasn't sure if the kit was causing it to shift firmly or the resistor. I will pull it out and check it just to be sure, as I have a couple of multimeters.
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