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

[Peter Lucas <lucas@xxxx>]

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