Re: [DML] Auto trans gov. problems...
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Re: [DML] Auto trans gov. problems...



At 5:23 AM -0500 2/24/01, RJRavalli@xxxx wrote:
Hello list I need some help desperately here. I just spent alot of
money I didn't have replacing my auto trans governor. Now I
found that it shifted well until I tried to drive it for more than
30 minutes. It started to slip out of third after driving it for
an extended period of time, and eventually didn't shift back into
third at all. Also, when it is upshifting *fine*, I find that it has
kind of a *rough* downshift, almost like it's slipping gears a bit.
BUT when it wasn't shifting into 3rd, the downshift was smooth.


In diagnosing this kind of problem, it is essential to first determine whether the governor is at fault or whether you have a mechanical problem. Fortunately this is easy to do. You need to build yourself a little test rig that lets you see (while you drive) what the governor is telling the transmission. This has been covered in the list in the past (check the archives), but here's the general idea:


1) Find the round black terminal block where the computer governor connects to the solenoid wires. It is in the engine compartment on the left firewall. Looks like some kind of diagnostic connector, but is really just a set of terminals. There are three wires going through this connector: One each for the two shift solenoids and a common. The center terminal is common. There are also two unused terminals. If we number the five terminals clockwise from 1 to 5, what we want to monitor is the potential between terminals 2 and 3 and between 3 and 4. If I remember correctly, the common (terminal 3) signal is +12V, and terminals 2 and 4 get pulled to ground by the governor to activate the respective solenoids. In any event, this can readily be determined with a test light or voltmeter. When the car is in neutral or low gear, you should read a 12V potential between 2 and 3 and also between 4 and 3. The trick is to be able to watch how this changes when the transmission is in action.

2) To accomplish this, run a 3-wire cable from this connector into the passenger compartment (4-wire telephone cable from Radio Shack is good for this). Connect the three wires to terminals 2, 3, and 4. Run the wire up your steering column so it comes out between the dash and the column.

3) Obtain 2 LEDs (Radio Shack again) one red and one green. You also need two 1500 ohm (brown green red stripes) resistors. Connect a resistor in series with the other end of the wires coming from terminals 2 and 4. Connect the other side of the resistors to the negative (unmarked) sides of the LEDs. Connect the positive (marked) sides of the LEDs (I'm doing this from memory--hope I don't have it all backwards) together and also to the wire coming from the center (#3) terminal. You can impress your friends by neatly packaging this precision instrument inside a 35mm film can.

4) Loosen your steering wheel adjustment clamp (you *do* know you have one, right?) and let the wheel drop. Position the film can between the steering column and the dash positioned so that you can see the LEDs while driving and slowly raise the wheel so that the can is firmly captured. Tighten the wheel in place.

5) Turn on the key. Both LEDs should now be shining cheerfully (assuming your governor is functioning semi-correctly).

6) Go for a ride. If he governor is operating correctly, the lights should go out one as a time, as the car shifts into second and third gear, respectively. In high gear, both lights should be off. When the vehicle downshifts, the lights should come back on in turn. It should now be an easy matter to decide whether your particular aberrant transmission behavior is due to bad advice from the governor or mechanical problems in the transmission itself.

If you are not comfortable dealing with such highly sophisticated digital circuitry, please get some advice from somebody who is. I may have gotten all this wrong and of course accept no responsibility for damage to you or your vehicle.

Hope this helps,

Pete Lucas
VIN #06703





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