In the last issue of Let’sPlay Ball!, we talked aboutsome of the unknowns of

the 450-43LE. That is, what youdon’t see in the books. We cov-ered:

• Valve body checkballlocations

• Wiring harness andlocation

• Common valve bodyproblems

• How to retrieve codes• Solenoid operation

and testing

In this issue, we’ll get up-close and personal with some ofthe internal components andthe code diagnosis you’ll needto know to get this unit out thedoor… the first time. We’llstart with how to diagnose thistransmission.

Code DescriptionThe codes on the

450-43LE can be retrievedmanually through the diagnos-tic connector, located under the

driver’s side of the dash

(refer to the April issue of GEARS).These codes are typically two digits(figure 1).

Every code represents a perceivedfailure to the computer. That doesn’tmean that code 11 (VSS Circuit Open)automatically tells you the VSS shouldbe replaced. On the contrary: It mayonly indicate a loose connection,engine interference, or something assimple as the VSS not being plugged in.

Some codes can lead you in thewrong direction altogether. For exam-ple, code 33 is: Timing solenoid circuitopen or shorted (figure 2). If you

A Look at the 450-43LE (Aisin Seiki), Part 2

A Look at the 450-43LE (Aisin Seiki), Part 2

LET’S PLAY BALL by Lance Wiggins

Every code

represents a

perceived failure

to the computer.

Figure 1

4 GEARS May-June 2003

Please note: In the April issue of GEARS,Aisin Seiki was spelled incorrectly. The correct spelling is listed above. Our apologies for this error.

retrieved this code,what would youthink is wrong?Most folks woulda u t o m a t i c a l l yassume the sole-noid failed —when the problemcould just as easilybe a shorted oropen wire to thesolenoid. This iswhere a solid diag-nostic routine iscritical for accuratediagnosis, no mat-ter what transmis-sion you’re work-ing on. Let’s look atthis code from twoperspectives, firstfrom after an over-haul and then a sec-ond time frombefore an overhaul.

After Overhaul Usually there

are only two possi-ble causes for a new code that appearsafter an overhaul:

1. a mechanical problem, such asbad parts, stuck valves, and soon, or…

2. a mistake during the rebuild.

Let’s use code 33 in this example.The definition for code 33 indicates thetiming solenoid is either open (no volt-age drop in the circuit) (figure 3), orshorted to ground. So the first thingthat all too many rebuilders will dowhen this code shows up immediatelyafter an overhaul is replace the solenoid— without checking the solenoid first.But when you examine the circuit thor-

oughly using a standard diagnostic rou-tine, nine times out of ten you won’tfind anything wrong with the solenoidor its circuit. So it’s important to under-stand the conditions that can cause thiscode to set.

The timing solenoid is used for the1–2 upshift, the 2–3 upshift, and the3–2 downshift. Its purpose is to controlthe orifice of the 2nd brake (B1), whichreduces shift shock. The computer usescode 33 to indicate a voltage drop prob-lem in the solenoid circuit. But it alsosets this code if the shift occurs tooquickly, which could be caused by asticking timing shift valve. This iswhere understanding the conditions that

will set a code, and following a logicaldiagnostic procedure, will help youavoid costly — and unnecessary —solenoid replacements.

Before OverhaulCodes that show up before an over-

haul should always be checked and thecondition repaired — or at least diag-nosed — before you even consideropening the transmission for repair. Thelast thing you want to do is go throughthe time and expense of an overhaul,only to end up with the same code thatyou had before. Not to mention the pos-sibility of missing the actual root causeof the code, only to have to pull the unit

GEARS May-June 2003 5

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 3

Figure 4B

apart again to correct it.This same code 33 can occur

before an overhaul, due to a failed 2nd

brake system. By understanding howthe system operates (Figure 4a and 4b)and sets codes, and using the samediagnostic routine, you can identify theroot of the problem faster and easierthan using the guess-and-replacemethod of diagnosis. Remember, theone thing the ECM can’t tell you iswhether the valve moved. If it did, youknow you’re going to have to dig downinto the transmission. On the otherhand, if the valve didn’t move, youshould at least be able to identify theroot cause of the trouble code by per-forming a standard diagnostic proce-dure on the solenoid and its control sys-tems.

Performing a diagnostic routine on

the 450-43LE transmission is easy: Allof the solenoids except the pressurecontrol solenoid are grounded constant-ly. The computer energizes them bysupplying a power (B+) signal (figure5).

There are three basic electricaltests you should perform for diagnosingany solenoid: voltage drop, resistanceand current draw. From there, whereyou go will depend on the results ofeach test. Start with the voltage droptest:• Backprobe the solenoid feed wire

with the positive lead from yourdigital meter.

• Connect the ground lead to a goodground.

• Set your meter to Volts DC.

Put the vehicle in the proper condi-

tion for the computer to energize thesolenoid. You may have to raise thedrive wheels and run the vehicle up to acertain speed for this to occur. Thencheck the voltage to the solenoid: Youshould see system voltage at the sole-noid when it’s supposed to energize.

If you don’t see system voltage,you’re dealing with one of three prob-lems:• Shorted solenoid• Open circuit or loose connection in

the wiring between the computerand the solenoid

• Faulty computer

Next, check the solenoid resist-ance:• Key off.• Unplug the solenoid harness from

the transmission.

6 GEARS May-June 2003

Figure 5

A Look at the 450-43LE (Aisin Seiki), Part 2

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TEST VALVE BODIES

TEST SOLENOIDS

BENCH TESTTRANSMISSIONS

Unit Tester -- This allows the operatorto test the hydraulic integrity of theindividual components in thetransmission.• With a simple connection, clutch andband operation can be diagnosed.• Bench testing the transmission cansave valuable time by reducingunnecessary installation and removal

Solenoid Tester -- Experts agreethat a solenoid tester is “a must”for any transmission shop, assolenoids represent the “weakestlink” in the transmission. Test upto 6 solenoids at a time with thisadvanced, yet easy-to-use, tester.Choose from manual or automatictest modes.

Valve Body Tester -- When precise control is amust, you can simulate the toughest drivingconditions while testing for suspect areas ofthe transmission’s electronic, hydraulic andvacuum systems. Tests valve bodies, solenoidsand pressure transducers using actual trans-mission pressures and heated oil.

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• Connect the positive meter lead tothe solenoid terminal on the trans-mission.

• Connect the negative meter lead toa good ground.

• Set your meter to Ohms.

Your meter should display between10 and 20 ohms resistance. If you seezero ohms, the solenoid or internaltransmission wiring is shorted. If yousee infinite resistance, the solenoid orwiring is open.

If the solenoid you’re checking issupposed to have extremely low resist-ance, such as a PWM solenoid, alwayszero your meter leads before begin-ning this test.

Finally, check the current drawfor the solenoid:• Switch your meter leads to the

10- or 20-amp sockets on yourmeter.

• Set your meter to read Amps.• Connect your meter in series

between the solenoid and a goodB+ power source.

Assuming aresistance of 10 to20 ohms, youshould have a cur-rent draw of 0.6 to1.2 amps. Zeroamps indicates anopen in the circuit(or a blown fuse inyour meter!); morethan about 1.5amps indicates ashorted or partiallyshorted solenoid orcircuit.

If the solenoidis one that’s sup-posed to have anextremely lowresistance, be care-ful with this test;don’t keep the sole-noid energized formore than a coupleseconds, or youcould burn it outduring testing.

Don’t forget,even if the solenoidchecks out good

electrically, it could still fail mechani-cally. You’ll have to perform a completemechanical function test once you havethe solenoid out of the unit.

Now let’s take a closer look at theinternal components of the 450-43LE.

Internal Case and Clutches The 450-43LE is built for torque:

The case-held clutches and supportingdrums are designed for pulling, pushingand hauling, whatever the load. There

are four shafts in this unit:1. Overdrive shaft2. Input Shaft3. Intermediate Shaft4. Output Shaft

There are six clutch sets and twoone-way clutches in this unit (figure 6).

The construction of the transmis-sion operation is similar to every Aisintransmission (figure 7).

The one-way clutch rotations are

8 GEARS May-June 2003

Figure 6

Figure 7

A Look at the 450-43LE (Aisin Seiki), Part 2

based on the rotation of the engine: The over-drive one-way clutch freewheels clockwisewhen the input shaft is rotated clockwise (fig-ure 8). The low one-way clutch is connected tothe case and the planetary rotates clockwise(figure 9).

To air check the transmission, apply air tothe feed holes at the case (figure 10).

Internal Valve BodyThe valve body is the last thing on the

agenda… and the item that’s overlooked most

10 GEARS May-June 2003

Figure 8

Figure 10

Shaft rotates clockwisePlanet rotates clockwise

Figure 9

A Look at the 450-43LE (Aisin Seiki), Part 2

O/D Clutch

O/D Brake

2nd Brake

Plug holeand air check rear clutch here

Low and reverse

FRT Clutch

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often. When disassembling the valvebodies (figures 11 and 12), there aresmall pins that will fall out without younoticing, so pay close attention towhere they belong.

The 450-43LE transmission isbig and bulky, but don’t let it beatyou in to submission. This transmis-sion will be around for a long timeand the more you know about it,

the better off you’ll be … and that’s the game!

12 GEARS May-June 2003

Figure 11

Figure 12

A Look at the 450-43LE (Aisin Seiki), Part 2

Lower Valve body

1. Manual Valve2. 2-3 Timing Valve3. 1-2 Shift Valve4. 3-4 Shift valve5. C0 Exhaust valve

6. Cut-Back Valve7. Pressure Regulator Valve

Assembly8. Lock-Up Control Valve

Upper Valve body

1. EPC and Throttle Valve2. Reducing Valve3. Lock-Up Signal Valve

4. Accumulator Control Valve5. Orifice control Valve6. 2-3 Shift Valve7. Secondary Regulator Valve8. Modulator Valve

9. Reverse Inhibitor Valve10. Low coast Modulator Valve11. Low Inhibitor Valve12. Check Valve